NSC COPEB888V Datasheet

COP888EB
8-Bit CMOS ROM Based Microcontrollers with 8k
Memory, CAN Interface, 8-Bit A/D, and USART

General Description

The COP888EB ROM based microcontrollers are highly in­tegrated COP8

™

Feature core devices with 8k memory and
advanced features including a CAN 2.0B (passive) interface,
A/D and USART. These single-chip CMOS devices are
suited for applications requiring a full featured controller with
a CAN interface, low EMI, and versatile communications in­terfaces. COP87L8EB/RB devices are pin and software
compatible 16k or 32k OTP (One Time Programmable) ver­sions for pre-production, and for use with a range of COP8
software and hardware development tools.

Features include an 8-bit memory mapped architecture, 10
MHz CKI with 1µs instruction cycle, two multi-function 16-bit
timer/counters, WATCHDOG

™

and Clock Monitor, CAN

2.0B (passive) interface, MICROWIRE/PLUS

™

serial I/O,
SPI master/slave interface, fully buffered USART, 8-bit A/D
with 8 channels, two power saving HALT/IDLE modes,
MIWU, idle timer, software selectable I/O options, low EMI

4.5V to 5.5V operation, and 44/68 pin packages.
Note: A companion device with CAN interface, less I/O and

memory, and PWM timer is the COP888BC.
Devices included in this datasheet are:

Device Memory (bytes) RAM (bytes) I/O Pins Packages Temperature

COP688EB 8k ROM 192 31 44 PLCC -55 to +125˚C
COP888EB 8k ROM 192 31 44 PLCC -40 to +85˚C
COP689EB 8k ROM 192 58 68 PLCC -55 to +125˚C
COP889EB 8k ROM 192 58 68 PLCC -40 to +85˚C

Key Features

n CAN bus interface, with Software Power save mode
n 8-bit A/D Converter with 8 channels
n Fully buffered USART
n Multi-input wake up (MIWU) on both Port L and M
n SPI Compatible Master/Slave Interface
n Quiet Design (Low Radiated Emissions)
n 8096 bytes of on-board ROM
n 192 bytes of on-board RAM

Additional Peripheral Features

n Idle timer (programmable)
n Two 16-bit timer, with two 16-bit registers supporting

— Processor independent PWM mode
— External Event counter mode
— Input capture mode

n WATCHDOG and Clock Monitor
n MICROWIRE/PLUS serial I/O

I/O Features

n Software selectable I/O options (TRI-STATE®outputs,

Push pull outputs, Weak pull up input, High impedance
input)

n Schmitt trigger inputs on Port G, L and M
n Packages: 44 PLCC with 31 I/O pins

68 PLCC with 58 I/O pins

CPU/Instruction Set Features

n 1 µs instruction cycle time

n Fourteen multi-sourced vectored interrupts servicing

— External interrupt
— Idle Timer T0
— Timers (T1 and T2) (4 Interrupts)
— MICROWIRE/PLUS and SPI
— Multi-input Wake up
— Software Trap
— CAN interface (3 interrupts)
— USART (2 Inputs)

n Versatile easy to use instruction set
n 8-bit stack pointer (SP) (Stack in RAM)
n Two 8-bit Register Indirect Memory Pointers (B, X)

Fully Static CMOS

n Two power saving modes: HALT, IDLE
n Single supply operation: 4.5V to 5.5V
n Temperature ranges: −40˚C to +85˚C and

−55˚C to +125˚C

Development Support

n Emulation and OTP devices
n Real time emulation and full program debug offered by

MetaLink Development System

COP8™, MICROWIRE™, MICROWIRE/PLUS™, and WATCHDOG™are trademarks of National Semiconductor Corporation.
TRI-STATE

®

is a registered trademark of National Semiconductor Corporation.

iceMASTER

®

is a registered trademark of MetaLink Corporation.

September 1999

COP888EB 8–Bit CMOS ROM Based Microcontrollers with 8k Memory, CAN Interface, 8–Bit A/D,

and USART

© 1999 National Semiconductor Corporation DS012837 www.national.com

Basic Functional Description

n CAN I/F—CAN serial bus interface block as described

in the CAN specification part 2.0B (Passive)
— Interface rates up to 250k bit/s are supported utilizing

standard message identifiers

n Programmable double buffered USART
n A/D—8-bit, 8 channel, 1-LSB Resolution, with improved

Source Impedance and improved channel to channel
cross talk immunity

n Multi-Input-Wake-Up (MIWU)—edge selectable wake-up

and interrupt capability via input port and CAN interface
(Port L, Port M and CAN I/F); supports Wake-Up
capability on SPI, USART, and T2 capture

n Port C—8-bit bi-directional I/O port
n Port D—8-bit Output port with high current drive

capability (10 mA)

n Port F—8-bit bidirectional I/O
n Port G—8-bit bidirectional I/O port, including alternate

functions for:
— MICROWIRE

™

Input and Output

— Timer 1 Input or Output (Depending on mode

selected)
— External Interrupt input
— WATCHDOG Output

n Port I—8-bit input port combining either digital input, or

up to eight A/D input channels

n Port L—8-bit bidirectional I/O port, including alternate

functions for:
— USART Transmit/Receive I/O
— Multi-input-wake up (MIWU on all pins)

n Port M—8-bit I/O port, with the following alternate

function
— SPI Interface
— MIWU

— CAN Interface Wake-up (MSB)
— Timer 2 Input or Output (Depending on mode

selected)

n Port N—8-bit bidirectional I/O

— SPI Slave Select Expander

n Two 16-bit multi-function Timer counters (T1 and T2)

plus supporting registers
— (I/P Capture, PWM and Event Counting)

n Idle timer—Provides a basic time-base counter, (with

interrupt) and automatic wake up from IDLE mode
programmable

n MICROWIRE/PLUS—MICROWIRE serial peripheral

interface, supporting both Master and Slave operation

n HALT and IDLE—Software programmable low current

modes
— HALT—Processor stopped, Minimum current
— IDLE — Processor semi-active more than 60%power

saving

n 8 kBytes ROM and 192 bytes of on board static RAM
n SPI Master/Slave interface includes 12 bytes Transmit

and 12 bytes Receive FIFO Buffers. Operates up to 1M
Bit/S

n On board programmable WATCHDOG and CLOCK

Monitor

Applications

n Automobile Body Control and Comfort System
n Integrated Driver Informaiton Systems
n Steering Wheel Control
n Car Radio Control Panel
n Sensor/Actuator Applications in Automotive and

Industrial Control

Block Diagram

DS012837-1

FIGURE 1. Block Diagram

www.national.com 2

Connection Diagrams

Plastic Chip Carrier

DS012837-2

Top View

Order Number COP888EB-XXX/V, COP688EB-XXX/V

See NS Plastic Chip Package Number V44A

Plastic Leaded Chip Carrier

DS012837-3

Top View

Order Number COP889EB-XXX/V, COP689EB-XXX/V

See NS Plastic Chip Package Number V68A

FIGURE 2. Connection Diagrams

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Connection Diagrams (Continued)

Pinouts for 44-Pin and 68-Pin Packages

Port

Type

ALT 44-Pin 68-Pin

Pin Function PLCC PLCC

G0 I/O INT 44 1
G1 I/O WDOUT 1 2
G2 I/O T1B 2 3
G3 I/O T1A 3 4
G4 I/O SO 4 5
G5 I/O SK 5 6
G6 I SI 6 7
G7 I CKO 7 8
D0 O 17 27
D1 O 18 28
D2 O 19 29
D3 O 20 30
D4 O 31
D5 O 32
D6 O 33
D7 O 34
I0 I ADCH0 36 53
I1 I ADCH1 37 54
I2 I ADCH2 38 55
I3 I ADCH3 39 56
I4 I ADCH4 57
I5 I ADCH5 58
I6 I ADCH6 59
I7 I ADCH7 60
L0 I/O MIWU 40 61
L1 I/O MIWU;CKX 41 62
L2 I/O MIWU;TDX 42 63
L3 I/O MIWU;RDX 43 64
L4 I/O MIWU 65
L5 I/O MIWU 66
L6 I/O MIWU 67
L7 I/O MIWU 68
M0 I/O MIWU;MISO 21 38
M1 I/O MIWU;MOSI 22 39
M2 I/O MIWU;SCK 23 40
M3 I/O MIWU;SS

24 41
M4 I/O MIWU;T2A 25 42
M5 I/O MIWU;T2B 26 43
M6 I/O MIWU 27 44
N0 I/O ESS0 12 18
N1 I/O ESS1 13 19
N2 I/O ESS2 14 20
N3 I/O ESS3 15 21
N4 I/O ESS4 22
N5 I/O ESS5 23
N6 I/O ESS6 24
N7 I/O ESS7 25

Port

Type

ALT 44-Pin 68-Pin

Pin Function PLCC PLCC

F0 I/O 10
F1 I/O 11
F2 I/O 12
F3 I/O 13
F4 I/O 14
C0 I/O 35
C1 I/O 36
C2 I/O 37
RX0 I 31 48
RX1 I 30 47
TX0 O 29 46
TX1 O 28 45
CANV

REF

32 49
CKI 8 9
RESET 16 26
DV

CC

10, 33 16, 50
GND 9, 11, 34 15, 17, 51
A/D V

REF

35 52

www.national.com 4

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage (V

CC

)6V

Voltage at Any Pin −0.3V to V

CC

+0.3V

Total Current into V

CC

Pins (Source) 90 mA
Total Current out of GND Pins (Sink) 100 mA
Storage Temperature Range −65˚C to +150˚C

Note 1:

Absolute maximum ratings indicate limits beyond which damage to
the device may occur. DC and AC electrical specifications are not ensured
when operating the device at absolute maximum ratings.

DC Electrical Characteristics COP88xEB

−40˚C ≤ TA≤ +85˚C

Parameter Conditions Min Typ Max Units

Operating Voltage 4.5 5.5 V
Power Supply Ripple (Note 2) Peak-to-Peak 0.1 V

CC

V

Supply Current V

CC

= 5.5V, tc=1µs 16 mA
CKI = 10 MHz (Note 3)
HALT Current (Notes 4, 5) V

CC

= 5.5V, CKI=0MHz

<

1µA

IDLE Current (Note 5) V

CC

= 5.5V, tc= 1 µs 5.5 mA
CKI = 10 MHz
Input Levels (V

IH,VIL

)

Reset, CKI

Logic High 0.8V

CC

V

Logic Low 0.2V

CC

V

All Other Inputs

Logic High 0.7V

CC

V

Logic Low 0.2V

CC

V

Hi-Z Input Leakage V

CC

= 5.5V

±

2µA

Input Pull-Up Current V

CC

= 5.5V, VIN= 0V −40 −250 µA
Port G, L and M Input Hysteresis (Note 8) 0.05V

CC

V

Output Current Levels

D Outputs

Source V

CC

= 4.5V, VOH= 3.3V −0.4 mA

Sink V

CC

= 4.5V, VOL= 1.0V 10 mA

CAN Transmitter Outputs

Source (Tx1) V

CC

= 4.5V, VOH=VCC−0.1V −1.5 mA

V

CC

= 4.5V, VOH=VCC− 0.6V −10 +5.0 mA

Sink (Tx0) V

CC

= 4.5V, VOL= 0.1V 1.5 mA

V

CC

= 4.5V, VOL= 0.6V 10 mA

All Others

Source (Weak Pull-Up) V

CC

= 4.5V, VOH= 2.7V −10 −110 µA

Source (Push-Pull) V

CC

= 4.5V, VOH= 3.3V −0.4 mA

Sink (Push-Pull) V

CC

= 4.5V, VOL= 0.4V 1.6 mA

TRI-STATE Leakage V

CC

= 5.5V

±

2.0 µA

Allowable Sink/Source Current per Pin

D Outputs (sink) 15 mA
Tx0 (Sink) (Note 8) 30 mA
Tx1 (Source) (Note 8) 30 mA
All Other 3mA

Maximum Input Current Room Temp

±

100 mA
without Latchup (Notes 6, 8)
RAM Retention Voltage, V

r

(Note 7) 500 ns Rise and Fall Time 2.0 V
Input Capacitance (Note 8) 7 pF
Load Capacitance on D2 1000 pF

Note 2: Maxiumum rate of voltage change must be<0.5V/ms

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DC Electrical Characteristics COP88xEB (Continued)

Note 3: Supply current is measured after running 2000 cycles with a square wave CKI input, CKO open, inputs at VCCor GND, and outputs open.
Note 4: The HALTmodewill stop CKI from oscillating in the Crystal configurations. Halt test conditions:All inputs tied to V

CC

; Port C, G, E, F, L, M and N I/Os con­figured as outputs and programmed low; D outputs programmed high. Parameter refers to HALT mode entered via setting bit 7 of the Port G data register. Part will
pull up CKI during HALT in crystal clock mode. Both CAN main comparator and the CAN Wakeup comparator need to be disabled.

Note 5: HALT and IDLE current specifications assume CAN block comparators are disabled.
Note 6: Pins G6 and RESET are designed with a high voltage input network. These pins allow input voltages greater than V

CC

and the pins will have sink current
to VCCwhen biased at voltages greater than VCC(the pins do not have source current when biasedatavoltagebelowVCC). The effective resistancetoVCCis 750Ω
(typical). These two pins will not latch up. The voltage at the pins must be limited to less than 14V.

Note 7: Condition and parameter valid only for part in HALT mode.
Note 8: Parameter characterized but not tested.

www.national.com 6

Absolute Maximum Ratings (Note 9)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Supply Voltage (V

CC

)7V

Voltage at Any Pin −0.3V to V

CC

+0.3V

Total Current into V

CC

Pins (Source) 100 mA
Total Current out of GND Pins (Sink) 110 mA
Storage Temperature Range −65˚C to +150˚C

Note 9:

Absolute maximum ratings indicate limits beyond which damage to
the device may occur. DC and AC electrical specifications are not ensured
when operating the device at absolute maximum ratings.

DC Electrical Characteristics COP68xEB

−55˚C ≤ TA≤ +125˚C

Parameter Conditions Min Typ Max Units

Operating Voltage 4.5 5.5 V
Power Supply Ripple (Note 10) Peak-to-Peak 0.1 V

CC

V

Supply Current V

CC

= 5.5V, tc=1µs 16 mA
CKI = 10 MHz (Note 11)
HALT Current (Notes 12, 13) V

CC

= 5.5V, CKI = 0 MHz 10 µA
IDLE Current (Note 13) V

CC

= 5.5V, tc= 1 µs 5.5 mA
CKI = 10 MHz
Input Levels (V

IH,VIL

)

Reset, CKI

Logic High 0.8V

CC

V

Logic Low 0.2V

CC

V

All Other Inputs

Logic High 0.7V

CC

V

Logic Low 0.2V

CC

V

Hi-Z Input Leakage V

CC

= 5.5V

±

5µA

Input Pull-Up Current V

CC

= 5.5V, VIN= 0V −35 −250 µA
Port G, L and M Input Hysteresis (Note 16) 0.05V

CC

V

Output Current Levels

D Outputs

Source V

CC

= 4.5V, VOH= 3.3V −0.4 mA

Sink V

CC

= 4.5V, VOL= 1.0V 9.0 mA

CAN Transmitter Outputs

Source (Tx1) V

CC

= 4.5V, VOH=VCC−0.1V −1.5 mA

V

CC

= 4.5V, VOH=VCC− 0.6V −10 mA

Sink (Tx0) V

CC

= 4.5V, VOL= 0.1V 1.5 mA

V

CC

= 4.5V, VOL= 0.6V 10 mA

All Others

Source (Weak Pull-Up) V

CC

= 4.5V, VOH= 2.7V −9.0 −100 µA

Source (Push-Pull) V

CC

= 4.5V, VOH= 3.3V −0.4 mA

Sink (Push-Pull) V

CC

= 4.5V, VOL= 0.4V 1.4 mA

TRI-STATE Leakage V

CC

= 5.5V

±

5.0 µA

Allowable Sink/Source Current per Pin

D Outputs (sink) 12 mA
Tx0 (Sink) (Note 16) 30 mA
Tx1 (Source) (Note 16) 30 mA
All Other 2.5 mA

Maximum Input Current Room Temp

±

100 mA
without Latchup (Notes 14, 16)
RAM Retention Voltage, V

r

(Note 15) 500 ns Rise and Fall Time 2.0 V
Input capacitance (Note 16) 7 pF
Load Capacitance on D2 1000 pF

Note 10: Maxiumum rate of voltage change must be<0.5V/ms

www.national.com7

DC Electrical Characteristics COP68xEB (Continued)

Note 11: Supply current is measured after running 2000 cycles with a square wave CKI input, CKO open, inputs at VCCor GND, and outputs open.
Note 12: The HALT mode will stop CKI from oscillating in the Crystal configurations. Halt test conditions: All inputs tied to V

CC

; Port C, G, E, F,L,MandNI/Oscon­figured as outputs and programmed low; D outputs programmed high. Parameter refers to HALT mode entered via setting bit 7 of the Port G data register. Part will
pull up CKI during HALT in crystal clock mode. Both CAN main comparator and the CAN Wakeup comparator need to be disabled.

Note 13: HALT and IDLE current specifications assume CAN block comparators are disabled.
Note 14: Pins G6 and RESET are designed with a high voltage input network. These pins allow input voltages greater than V

CC

and the pins will have isnk current
to VCCwhen biased at voltages greater than VCC(the pins do not have source current when biasedatavoltagebelowVCC). The effective resistancetoVCCis 750Ω
(typical). These two pins will not latch up. The voltage at the pins must be limited to less than 14V.

Note 15: Condition and parameter valid only for part in HALT mode.
Note 16: Parameter characterized but not tested.

AC Electrical Characteristics COP68xEB and COP88xEB

−55˚C ≤ TA≤ +125˚C

Parameter Conditions Min Typ Max Units

Instruction Cycle Time (t

c

)

Crystal/Resonator V

CC

≥ 4.5V 1.0 DC µs

Inputs

t

SETUP

VCC≥ 4.5V 200 ns

t

HOLD

VCC≥ 4.5V 60 ns

Output Propagation Delay (t

PD1,tPD0

) (Note 19) CL= 100 pF, RL= 2.2 kΩ

SK, SO V

CC

≥ 4.5V 0.7 µs

All others V

CC

≥ 4.5V 1 µs

MICROWIRE

Setup Time (t

UWS

) (Note 20) 20 ns

Hold Time (t

UWH

) (Note 20) 56 ns

Output Pop Delay (t

UPD

) 220 ns

Input Pulse Width

Interrupt High Time 1 t

c

Interrupt Low Time 1t

c

Timer 1, 2 High Time 1 t

c

Timer 1, 2 Low Time 1 t

c

Reset Pulse Width (Note 20) 1.0 µs

tc= Instruction Cycle Time
Note 17: The maximum bus speed achievable with the CANinterfaceisa function of crystal frequency,message length and software overhead. The device can sup-

port a bus speed of up to 1 Mbit/S with a 10 MHz oscillator and 2 byte messages. The 1M bus speed refers to the rate at which protocol and data bits are transferred
on the bus. Longer messages require slower bus speeds due to the time required for software intervention between data bytes. The device will support a maximum
of 125k bits/s with eight byte messages and a 10 MHz oscillator.

Note 18: For device testing purpose of all AC parameters, V

OH

will be tested at 0.5*VCC.

Note 19: The output propagation delay is referenced to the end of the instruction cycle where the output change occurs.
Note 20: Parameter not tested.

On-Chip Voltage Reference

−55˚C ≤ TA≤ +125˚C

Parameter Conditions Min Max Units

Reference Voltage I

OUT

<

80 µA, 0.5VCC−0.12 0.5VCC+0.12 V

V

REF

VCC=5V

Reference Supply I

OUT

= 0A, (No Load) 120 µA

Current, I

DD

VCC= 5V (Note 21)

Note 21: Reference supply IDDis supplied for information purposes only, it is not tested.

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CAN Comparator DC and AC Characteristics

4.8V ≤ VCC≤ 5.2V, −40˚C ≤ TA≤ +125˚C

Parameter Conditions Min Typ Max Units

Differential Input Voltage

±

25 mV

Input Offset Voltage 1.5V

<

V

IN

<

VCC−1.5V

±

10 mV

Input Common Mode 1.5 V

CC

−1.5 V
Voltage Range
Input Hysteresis 8 mV

A/D Converter Specifications

(4.5V ≤ VCC≤ 5.5V) (VSS− 0.050V) ≤ Any Input ≤ (VCC+ 0.050V)

Parameter Conditions Min Typ Max Units

Resolution 8 Bits
Absolute Accuracy V

REF=VCC

±

2 LSB

Non-Linearity

±

1 LSB
Deviation from the Best Straight Line
Differential Non-Linearity

±

1 LSB
Common Mode Input Range (Note 24) GND V

CC

V

DC Common Mode Error

±

0.5 LSB
Off Channel Leakage Current 1 2.0 µA
On Channel Leakage Current 1 2.0 µA
A/D Clock Frequency (Note 23) 0.1 1.67 MHz
Conversion Time (Note 22) 17 A/D Clock Cycles
Internal Reference Resistance Turn-On Time (Note 25) 1 µs

Note 22: Conversion Time includes sample and hold time.
Note 23: See Prescaler description.
Note 24: For V

IN

(−)>=VIN(+) the digital output code will be 0000 0000. Two on-chip doides are ties to each analog input. The diodes will forward conduct for analog

input voltages below ground or above the V

CC

supply.Be careful, during testing at low VCClevels (4.5V), as high level analog inputs (5V) can cause this input diode
to conduct — especially at elevated temperatures, and cause errors for analog inputs near full-scale. The spec allows 50 mV forward bias of either diode. This means
that as long as the analog V

IN

does not exceed the supply voltage by more than 50 mV, the output code will be correct. To achieve an absolute 0 VDCto 5 VDCinput

voltage range will therefore require a minimum supply voltage of 4.950 V

DC

over temperature variations, initial tolerance and loading.

Note 25: Time for internal reference resistance to turn on after coming out of Halt or Idle Mode.

DS012837-4

FIGURE 3. MICROWIRE/PLUS Timing Diagram

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A/D Converter Specifications (Continued)

Typical Performance Characteristics (−55˚C ≤ T

A

=

+125˚C)

DS012837-5

FIGURE 4. SPI Timing Diagram

DS012837-57 DS012837-58

DS012837-59 DS012837-60

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Typical Performance Characteristics (−55˚C ≤ T

A

=

+125˚C) (Continued)

Pin Description

VCCand GND are the power supply pins.
CKI is the clock input. The clock can come from a crystal os-

cillator (in conjunction with CKO). See Oscillator Description
section.

RESET is the master reset input. See Reset Description sec­tion.

The device contains seven bidirectional 8-bit I/O ports (C, E,
F, G, L, M, N) where each individual bit may be indepen­dently configured as an input (Schmitt trigger inputs on all
ports), output or TRI-STATE under program control. Three
data memory address locations are allocated for each of
these I/O ports. Each I/O port has two associated 8-bit
memory mapped registers, the CONFIGURATION register
and the output DATA register.A memory mapped address is
also reserved for the input pins of each I/O port. (See the
memory map for the various addresses associated with the
I/O ports.)

Figure 5

shows the I/O port configurations for the
device. The DATA and CONFIGURATION registers allow for
each port bit to be individually configured under software
control as shown below:

Configuration Data Port Set-Up

Register Register

0 0 Hi-Z Input

(TRI-STATE Output)
0 1 Input with Weak Pull-Up
1 0 Push-Pull Zero Output
1 1 Push-Pull One Output

Port L and M are 8-bit I/O ports, they support Multi-Input
Wake-up (MIWU) on all eight pins. All L-pins and M-pins
have Schmitt triggers on the inputs.

Port L and M only have one (1) interrupt vector.

Port L has the following alternate features:

L7 MIWU
L6 MIWU
L5 MIWU
L4 MIWU
L3 MIWU or RDX
L2 MIWU or TDX
L1 MIWU or CKX
L0 MIWU

Port G is an 8-bit port with 5 I/O pins (G0–G5), an input pin
(G6), and one dedicated output pin (G7). Pins G0–G6 all
have Schmitt Triggers on their inputs. G7 serves as the dedi­cated output pin for the CKO clock output. There are two reg­isters associated with the G Port, a data register and a con­figuration register. Therefore, each of the 6 I/O bits (G0–G5)
can be individually configured under software control.

Since G6 is an input only pin and G7 is the dedicated CKO
clock output pin the associated bits in the data and configu­ration registers for G6 and G7 are used for special purpose
functions as outlined below. Reading the G6 and G7 data
bits will return zeroes.

Note that the chip will be placed in the HALTmode by wirting
a ’’1” to bit 7 of the Port G Data Register. Similarly the chip
will be placed in the IDLE mode by writing a “1” to bit 6 of the
Port G Data Register.

DS012837-61

DS012837-6

FIGURE 5. I/O Port Configurations

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Pin Description (Continued)

Writing a “1” to bit 6 of the Port G Configuration Register en­ables the MICROWIRE/PLUS to operate with the alternate
phase of the SK clock

Config. Reg. Data Reg.

G7 CLKDLY HALT
G6 Alternate SK IDLE

Port G has the following alternate features:

G6 SI (MICROWIRE Serial Data Input)
G5 SK (MICROWIRE Serial Clock)
G4 SO (MICROWIRE Serial Data Output)
G3 T1A (Timer I/O)
G2 (Timer T1 Capture Input)
G1 Dedicated WATCHDOG output
G0 INTR (External Interrupt Input)

Port G has the following dedicated function:

G7 CKO Oscillator dedicated output

Port M is a bidirectional I/O, it may be configured in software
as Hi-Z input, weak pull-up, or push-pull output. These pins
may be used as general purpose input/output pins or for se­lected altlernate functions.

Port M pins have optional alternate functions. Each pin
(M0–M5) has been assigned an alternate data, configura­tion, or wakeup source. If the respective alternate function is
selected the content of the associated bits in the configura­tion and/or data register are ignored. If an alternate wakeup
source is selected the input level at the respective pin will be
ignored for the purpose of triggering a wakeup event, how­ever it will still be possible to read that pin by accessing the
input register. The SPI (Serial Peripheral Interface) block, for
example, uses four of the Port M pins to automatically re­configure its MISO (Master Input, Slave Output), MOSI
(Master Output, Slave Input), SCK (Serial Clock) and Slave­Select pins as inputs or outputs, depending on whether the
interface has been configured as a Master or Slave. When
the SPI interface is disabled those pins are available as gen­eral purpose I/O pins configurable by user software writing to
the associated data and configuration bits. The CAN inter­face on the device makes use of one of the Port M’s alter­nate wake-ups, to trigger a wakeup if such a condition has
been detected on the CAN’s dedicated receive pins.

Port M has the following alternate pin functions:

M7 Multi-input Wakeup or CAN
M6 Multi-input Wakeup
M5 Multi-input Wakeup or T2B
M4 Multi-input Wakeup or T2A
M3 Multi-input Wakeup or SS
M2 Multi-input Wakeup or SCK
M1 Multi-input Wakeup or MOSI
M0 Multi-input Wakeup or MISO

Ports C, E, F and N are general-purpose, bidirectional I/O
ports.

Any device package that has Port C, E, F,M, N but has fewer
than eight pins, contains unbonded, floating pads internally
on the chip. For these types of devices, the software should
writea1totheconfiguration register bits corresponding to
the non-existent port pins. This configures the port bits as
outputs, thereby reducing leakage current of the device.

Port N is an 8-bit wide port with alternate function capability
used for extending the slave select (SS) lines of the on SPI
interface. The SPI expander block provides mutually exclu­sive slave select extension signals (ESS0 to ESS7) accord­ing to the state of the SS line and specific contents of the SPI
shift register. These slave select extension lines can be
routed to the Port N I/O pins by enabling the alternate func­tion of the port in the PORTNX register. If enabled, the inter­nal signal on the ESSx line causes the ports state to change
exactly like a change to the PORTND register. It is the user’s
responsibility to switch the port to an output when enabling
the alternate function.

Port N has the following alternate pin functions:

N7 ESS7
N6 ESS6
N5 ESS5
N4 ESS4
N3 ESS3
N2 ESS2
N1 ESS1
N0 ESS0

CAN pins: For the on-chip CAN interface this device has five
dedicated pins with the following features:

V

REF

On-chip reference voltage with the value of VCC/2
Rx0 CAN receive data input pin.
Rx1 CAN receive data input pin.
Tx0 CAN transmit data output pin. This pin may be put in

the TRI-STATE mode with the TXEN0 bit in the CAN

Bus control register.
Tx1 CAN transmit data output pin. This pin may be put in

the TRI-STATE mode with the TXEN1 bit in the CAN

Bus control register.

ALTERNATE PORT FUNCTIONS

Many general-purpose pins have alternate functions. The
software can program each pin to be used either for a
general-purpose or for a specific function.The chip hardware
determines which of the pins have alternate functions, and
what those functions are. This section lists the alternate
functions available on each of the pins.

Port D is an 8-bit output port that is preset high when RESET
goes low. The user can tie two or more port D outputs (ex­cept D2) together in order to get a higher drive.

Note: Care must be exercised with D2 pin operation. At RESET, the external

loads on this pin must ensure that the output voltages stay above 0.8
V

CC

to prevent the chip from entering special modes.Also keep the ex-

ternal loading on D2 to

<

1000 pF.

Port I is an 8-bit Hi-Z input port, and also provides the analog
inputs to the A/D converter. If unterminated, Port I pins will
draw power only when addressed.

Functional Description

The architecture of the device utilizes a modified Harvard ar­chitecture. With the Harvard architecture, the control store
program memory (ROM) is separated from the data store
memory (RAM). Both ROM and RAM have their own sepa­rate addressing space with separate address buses. The ar­chitecture, though based on Harvard architecture, permits
transfer of data from ROM to RAM.

www.national.com 12

Functional Description (Continued)

CPU REGISTERS

The CPU can do an 8-bit addition, subtraction, logical or shift
operation in one instruction (t

c

) cycle time.
There are five CPU registers:
A is the 8-bit Accumulator Register
PC is the 15-bit Program Counter Register
PU is the upper 7 bits of the program counter (PC)
PL is the lower 8 bits of the program counter (PC)
B is an 8-bit RAM address pointer, which can be optionally

post auto incremented or decremented.
X is an 8-bit alternate RAM address pointer, which can be

optionally post auto incremented or decremented.
SP is the 8-bit stack pointer, which points to the subroutine/

interrupt stack (in RAM). The SP is initialized to RAM ad­dress 02F with reset.

All the CPU registers are memory mapped with the excep­tion of the Accumulator (A) and the Program Counter (PC).

PROGRAM MEMORY

Program memory for the device consists of 8 kbytes of ROM.
These bytes may hold program instructions or constant data
(data tables for the LAID instruction, jump vectors for the JID
instruction and interrupt vectors for the VIS instruction). The
program memory is addressed by the 15-bit program
counter (PC). All interrupts in the device vector to program
memory location 0FF Hex.

DATA MEMORY

The data memory address space includes the on-chip RAM
and data registers, the I/O registers (Configuration, Data and
Pin), the control registers, the MICROWIRE/PLUS SIO shift
register, and the various registers, and counters associated
with the timers (with the exception of the IDLE timer). Data
memory is addressed directly by the instruction or indirectly
by the B, X and SP pointers.

The device has 192 bytes of RAM. Sixteen bytes of RAM are
mapped as “registers” at addresses 0F0 to 0FF Hex. These
registers can be loaded immediately, and also decremented
and tested with the DRSZ (decrement register and skip if
zero) instruction. The memory pointer registers X, SP,and B
are memory mapped into this space at address locations
0FC to 0FE Hex respectively, with the other registers (other
than reserved register 0FF) being available for general us­age.

The instruction set permits any bit in memory to be set, reset
or tested. All I/O and registers (except A and PC) are
memory mapped; therefore I/O bits and register bits can be
directly and individually set, reset and tested. The accumula­tor (A) bits can also be directly and individually tested.

Note: RAM contents are undefined upon power-up.

RESET

The RESET input when pulled low initializes the microcon­troller. Initialization will occur whenever the RESET input is
pulled low. Upon initialization, the data and configuration
registers for Ports L and G, are cleared, resulting in these
Ports being initialized to the TRI-STATE mode. Port D is ini­tialized high with RESET. The PC, CNTRL, and INCTRL
control registers are cleared. The Multi-Input Wakeup regis­ters WKEN, WKEDG, and WKPND are cleared. The Stack
Pointer, SP, is initialized to 06F Hex.

The following initializations occur with RESET:

SPI:

SPICNTRL: Cleared
SPISTAT: Cleared

STBE Bit: Set
T1CNTRL & T2CNTRL: Cleared
ITMR: Cleared and IDLE timer period is reset to 4k Instr.
CLK
ENAD: Cleared
ADDSLT: Random
SIOR: Unaffected after RESET with power already ap-

plied.
Random after RESET at power on.
Port L: TRI-STATE
Port G: TRI-STATE
Port D: HIGH
PC: CLEARED
PSW, CNTRL and ICNTRL registers: CLEARED

Accumulator and Timer 1:

RANDOM after RESET with power already applied
RANDOM after RESET at power-on

SP (Stack Pointer): Loaded with 6F Hex
B and X Pointers:

UNAFFECTED after RESET with power already applied
RANDOM after RESET at power-up

RAM:

UNAFFECTED after RESET with power already applied
RANDOM after RESET at power-up

CAN: The CAN Interface comes out of external reset in the

“error-active” state and waits until the user’s soft­ware sets either one or both of the TXEN0, TXEN1
bits to “1”. After that, the device will not start trans­mission or reception of a frame util eleven consecu­tive “recessive” (undriven) bits have been received.
This is done to ensure that the output drivers are not

enamble during an active message on the bus.
CSCAL, CTIM, TCNTL, TEC, REC: CLEARED
RTSTAT: CLEARED with the exception of the TBE bit which

is set to 1
RID, RIDL, TID, TDLC: RANDOM
WATCHDOG: The device comes out of reset with both the

WATCHDOG logic and the Clock Monitor
detector armed, with the WATCHDOG ser­vice window bits set and the Clock Monitor
bit set. The WATCHDOG and Clock Monitor
circuits are inhibited during reset. The
WATCHDOG service window bits being ini­tialized high default to the maximum
WATCHDOG service window of 64k t

c

clock
cycles. The Clock Monitor bit being initial­ized high will cause a Clock Monitor bit be­ing initialized high will cause a Clock Moni­tor error following reset if the clock has not
reached the minimum specified frequency
at the termination of reset. A Clock Monitor
error will cause an active low error output on
pin G1. This error output will continue until
16 t

c

–32 tcclock cycles following the clock
frequency reaching the minimum specified
value, at which time the G1 output will enter
the TRI-STATE mode.

www.national.com13

Functional Description (Continued)

The RESET signal goes directly to the
HALT latch to restart a halted chip.

When using external reset, the external RC network shown
in

Figure 6

should be used to ensure that the RESET pin is
held low until the power supply to the chip stabilizes. Under
no circumstances should the RESET pin be allowed to float.

Oscillator Circuits

The chip can be driven by a clock input on the CKI input pin
which can be between DC and 10 MHz. The CKO output
clock is on pin G7. The CKI input frequency is divided by 10
to produce the instruction cycle clock (1/t

c

).

Figure 7

shows the Crystal diagram.

CRYSTAL OSCILLATOR

CKI and CKO can be connected to make a closed loop crys­tal (or resonator) controlled oscillator.

Table 1 shows the component values required for various
standard crystal values.

TABLE 1. Crystal Oscillator Configuration, TA= 25˚C

R1 R2 C1 C2 CKI Freq. Conditions

(kΩ)(MΩ) (pF) (pF) (MHz)

0 1 30 30–36 10 V

CC

=5V

0 1 30 30–36 4 V

CC

=5V

0 1 200 100–150 0.455 V

CC

=5V

Control Registers

CNTRL Register (Address X'00EE)

T1C3 T1C2 T1C1 T1C0 MSEL IEDG SL1 SL0

Bit 7 Bit 0

The Timer1 (T1) and MICROWIRE/PLUS control register
contains the following bits:

T1C3 Timer T1 mode control bit
T1C2 Timer T1 mode control bit
T1C1 Timer T1 mode control bit
T1C0 Timer T1 Start/Stop control in timer

modes 1 and 2, T1 Underflow Interrupt
Pending Flag in timer mode 3

MSEL Selects G5 and G4 as MICROWIRE/PLUS

signals SK and SO respectively

IEDG External interrupt edge polarity select

(0 = Rising edge, 1 = Falling edge)

SL1 & SL0 Select the MICROWIRE/PLUS clock divide

by (00 = 2, 01 = 4, 1x = 8)

CNTRL Register (Address X'00EE)

T1C3 T1C2 T1C1 T1C0 MSEL IEDG SL1 SL0
Bit 7 Bit 0

The Timer1 (T1) and MICROWIRE/PLUS control register
contains the following bits:

T1C3 Timer T1 mode control bit
T1C2 Timer T1 mode control bit
T1C1 Timer T1 mode control bit
T1C0 Timer T1 Start/Stop control in timer

modes 1 and 2, T1 Underflow Interrupt
Pending Flag in timer mode 3

MSEL Selects G5 and G4 as MICROWIRE/PLUS

signals SK and SO respectively

IEDG External interrupt edge polarity select

(0 = Rising edge, 1 = Falling edge)

SL1 & SL0 Select the MICROWIRE/PLUS clock divide

by (00 = 2, 01 = 4, 1x = 8)

PSW Register (Address X'00EF)

HC C T1PNDA T1ENA EXPND BUSY EXEN GIE

Bit 7 Bit 0

The PSW register contains the following select bits:

HC Half Carry Flag
C Carry Flag
T1PNDA Timer T1 Interrupt Pending Flag (Autoreload

RA in mode 1, T1 Underflow in Mode 2, T1A
capture edge in mode 3)

T1ENA Timer T1 Interrupt Enable for Timer Underflow

or T1A Input capture edge
EXPND External interrupt pending
BUSY MICROWIRE/PLUS busy shifting flag
EXEN Enable external interrupt
GIE Global interrupt enable (enables interrupts)

The Half-Carry flag is also affected by all the instructions that
affect the Carry flag. The SC (Set Carry) and R/C (Reset
Carry) instructions will respectively set or clear both the carry
flags. In addition to the SC and R/C instructions, ADC,
SUBC, RRC and RLC instructions affect the Carry and Half
Carry flags.

ICNTRL Register (Address X'00E8)

Reserved LPEN T0PND T0EN µWPND µWEN T1PNDB T1ENB

Bit 7 Bit 0

DS012837-7

RC>5 x Power Supply Rise Time

FIGURE 6. Recommended Reset Circuit

DS012837-8

FIGURE 7. Crystal Oscillator Diagram

www.national.com 14

Control Registers (Continued)

The ICNTRL register contains the following bits:
Reserved This bit is reserved and should be zero

LPEN L Port/M Port Interrupt Enable (Multi-Input

Wakeup/Interrupt)
T0PND Timer T0 Interrupt pending
T0EN Timer T0 Interrupt Enable (Bit 12 toggle)
µWPND MICROWIRE/PLUS interrupt pending
µWEN Enable MICROWIRE/PLUS interrupt
T1PNDBTimer T1 Interrupt Pending Flag for T1B capture

edge
T1ENB Timer T1 Interrupt Enable for T1B Input capture

edge

T2CNTRL Register (Address X'00C6)

T2C3 T2C2 T2C1 T2C0 T2PNDA T2ENA T2PNDB T2ENB
Bit 7 Bit 0

The T2CNTRL control register contains the following bits:

T2C3 Timer T2 mode control bit
T2C2 Timer T2 mode control bit
T2C1 Timer T2 mode control bit
T2C0 Timer T2 Start/Stop control in timer

modes 1 and 2, T2 Underflow Interrupt Pend­ing Flag in timer mode 3

T2PNDA Timer T2 Interrupt Pending Flag (Autoreload

RA in mode 1, T2 Underflow in mode 2, T2A
capture edge in mode 3)

T2ENA Timer T2 Interrupt Enable for Timer Underflow

or T2A Input capture edge

T2PNDB Timer T2 Interrupt Pending Flag for T2B cap-

ture edge

T2ENB Timer T2 Interrupt Enable for Timer Underflow

or T2B Input capture edge

Timers

The device contains a very versatile set of timers (T0, T1 and
T2). All timers and associated autoreload/capture registers
power up containing random data.

TIMER T0 (IDLE TIMER)

The device supports applications that require maintaining
real time and low power with the IDLE mode. This IDLE
mode support is furnished by the IDLE timer T0, which is a
16-bit timer. The Timer T0 runs continuously at the fixed rate
of the instruction cycle clock, t

c

. The user cannot read or

write to the IDLE Timer T0, which is a count down timer.
The Timer T0 supports the following functions:

•

Exit out of the Idle Mode (See Idle Mode description)

•

WATCHDOG logic (See WATCHDOG description)

•

Start up delay out of the HALT mode

Figure 8

is a functional block diagram showing the structure

of the IDLE Timer and its associated interrupt logic.
Bits 11 through 15 of the ITMR register can be selected for

triggering the IDLE Timer interrupt. Each time the selected
bit underflows (every 4k, 8k, 16k, 32k or 64k instruction
cycles), the IDLE Timer interrupt pending bit T0PND is set,
thus generating an interrupt (if enabled), and bit 6 of the Port
G data register is reset, thus causing an exit from the IDLE
mode if the device is in that mode.

In order for an interrupt to be generated, the IDLE Timer in­terrupt enable bit T0EN must be set, and the GIE (Global In­terrupt Enable) bit must also be set. The T0PND flag and
T0EN bit are bits 5 and 4 of the ICNTRL register, respec­tively.The interrupt can be used for any purpose. Typically,it
is used to perform a task upon exit from the IDLE mode. For
more information on the IDLE mode, refer to the Power Save
Modes section.

The Idle Timer period is selected by bits 0–2 of the ITMR
register Bits 3–7 of the ITMR Register are reserved and
should not be used as software flags.

ITMR Register (Address X’0xCF)

Reserved ITSEL2 ITSEL1 ITSLE0

Bit 7 Bit 0

TABLE 2. Idle Timer Window Length

ITSEL2 ITSEL1 ITSEL0 Idle Timer Period

(Instruction Cycles)

0 0 0 4,096
0 0 1 8,192
0 1 0 16,384
0 1 1 32,768
1 X X 65,536

The ITMR register is cleared on Reset and the Idle Timer pe­riod is reset to 4,096 instruction cycles.

Any time the IDLE Timer period is changed there is the pos­sibility of generating a spurious IDLE Timer interrupt by set­ting the T0PND bit. The user is advised to disable IDLE
Timer interrupts prior to changing the value of the ITSEL bits
of the ITMR Register and then clear theT0PND bit before at­tempting to synchronize operation to the IDLE Timer.

TIMER T1 and TIMER T2

The device has a set of three powerful timer/counter blocks,
T1 and T2. The associated features and functioning of a
timer block are described by referring to the timer block Tx.
Since the three timer blocks, T1 and T2 are identical, all
comments are equally applicable to either of the three timer
blocks.

Each timer block consists of a 16-bit timer, Tx, and two sup­porting 16-bit autoreload/capture registers, RxA and RxB.
Each timer block has two pins associated with it, TxA and

DS012837-9

FIGURE 8. Functional Block Diagram for Idle Timer T0

www.national.com15

Timers (Continued)

TxB. The pin TxA supports I/O required by the timer block,
while the pin TxB is an input to the timer block. The powerful
and flexible timer block allows the device to easily perform all
timer functions with minimal software overhead. The timer
block has three operating modes: Processor Independent
PWM mode, External Event Counter mode, and Input Cap­ture mode.

The control bits TxC3,TxC2, and TxC1 allow selection of the
different modes of operation.

Mode 1. Processor Independent PWM Mode

As the name suggests, this mode allows the device to gen­erate a PWM signal with very minimal user intervention.

The user only has to define the parameters of the PWM sig­nal (ON time and OFF time).Once begun, the timer block will
continuously generate the PWM signal completely indepen­dent of the microcontroller. The user software services the
timer block only when the PWM parameters require updat­ing.

In this mode the timer Tx counts down at a fixed rate of t

c

.
Upon every underflow the timer is alternately reloaded with
the contents of supporting registers, RxA and RxB. The very
first underflow of the timer causes the timer to reload from
the register RxA. Subsequent underflows cause the timer to
be reloaded from the registers alternately beginning with the
register RxB.

The Tx Timer control bits, TxC3, TxC2 and TxC1 set up the
timer for PWM mode operation.

Figure 9

shows a block diagram of the timer in PWM mode.

The underflows can be programmed to toggle the TxAoutput
pin. The underflows can also be programmed to generate in­terrupts.

Underflows from the timer are alternately latched into two
pending flags, TxPNDA and TxPNDB. The user must reset
these pending flags under software control. Two control en­able flags, TxENA and TxENB, allow the interrupts from the
timer underflow to be enabled or disabled. Setting the timer
enable flag TxENA will cause an interrupt when a timer un­derflow causes the RxA register to be reloadedinto the timer.
Setting the timer enable flag TxENB will cause an interrupt
when a timer underflow causes the RxB register to be re­loaded into the timer. Resetting the timer enable flags will
disable the associated interrupts.

Either or both of the timer underflow interrupts may be en­abled. This gives the user the flexibility of interrupting once

per PWM period on either the rising or falling edge of the
PWM output. Alternatively, the user may choose to interrupt
on both edges of the PWM output.

Mode 2. External Event Counter Mode

This mode is quite similar to the processor independent
PWM mode described above. The main difference is that the
timer,Tx, is clocked by the input signal from theTxA pin. The
Tx timer control bits, TxC3, TxC2 andTxC1 allow the timer to
be clocked either on a positive or negative edge from the
TxA pin. Underflows from the timer are latched into the TxP­NDA pending flag. Setting the TxENA control flag will cause
an interrupt when the timer underflows.

In this mode the input pin TxB can be used as an indepen­dent positive edge sensitive interrupt input if the TxENB con­trol flag is set. The occurrence of the positive edge on the
TxB input pin is latched to the TxPNDB flag.

Figure 10

shows a block diagram of the timer in External

Event Counter mode.

Mode 3. Input Capture Mode

The device can precisely measure external frequencies or
time external events by placing the timer block, Tx, in the in­put capture mode.

In this mode, the timer Tx is constantly running at the fixed t

c

rate. The two registers, RxA and RxB, act as capture regis­ters. Each register acts in conjunction with a pin. The register
RxAacts in conjunction with the TxApin and the register RxB
acts in conjunction with the TxB pin.

The timer value gets copied over into the register when a
trigger event occurs on its corresponding pin. Control bits,
TxC3, TxC2 and TxC1, allow the trigger events to be speci­fied either as a positive or a negative edge. The trigger con­dition for each input pin can be specified independently.

The trigger conditions can also be programmed to generate
interrupts. The occurrence of the specified trigger condition
on the TxA and TxB pins will be respectively latched into the
pending flags, TxPNDA and TxPNDB. The control flag
TxENA allows the interrupt on TxA to be either enabled or
disabled. Setting the TxENA flag enables interrupts to be
generated when the selected trigger condition occurs on the
TxA pin. Similarly, the flag TxENB controls the interrupts
from the TxB pin.

Underflows from the timer can also be programmed to gen­erate interrupts. Underflows are latched into the timer TxC0
pending flag (the TxC0 control bit serves as the timer under­flow interrupt pending flag in the Input Capture mode). Con-

DS012837-10

FIGURE 9. Timer in PWM Mode

DS012837-11

Note: The PWM output is not available in this mode since the TxA pin is
being used as the counter input clock.

FIGURE 10. Timer in External Event Counter Mode

www.national.com 16

Timers (Continued)

sequently, the TxC0 control bit should be reset when enter­ing the Input Capture mode. The timer underflow interrupt is
enabled with the TxENA control flag. When a TxA interrupt
occurs in the Input Capture mode, the user must check both
whether a TxA input capture or a timer underflow (or both)
caused the interrupt.

Figure 11

shows a block diagram of the timer in Input Cap-

ture mode.

TIMER CONTROL FLAGS

The control bits and their functions are summarized below.

TxC3 Timer mode control
TxC2 Timer mode control
TxC1 Timer mode control
TxC0 Timer Start/Stop control in Modes 1 and 2 (Pro-

cessor Independent PWM and External Event
Counter), where 1 = Start, 0 = Stop

Timer Underflow Interrupt Pending Flag in

Mode 3 (Input Capture)
TxPNDA Timer Interrupt Pending Flag
TxENA Timer Interrupt Enable Flag

1 = Timer Interrupt Enabled

0 = Timer Interrupt Disabled
TxPNDB Timer Interrupt Pending Flag
TxENB Timer Interrupt Enable Flag

1 = Timer Interrupt Enabled

0 = Timer Interrupt Disabled

DS012837-12

FIGURE 11. Timer in Input Capture Mode

www.national.com17

Timers (Continued)

The timer mode control bits (TxC3, TxC2 and TxC1) are detailed below:

Mode TxC3 TxC2 TxC1 Description

Interrupt A

Source

Interrupt B

Source

Timer

Counts On

1

1 0 1 PWM: TxA Toggle Autoreload RA Autoreload RB t

C

1 0 0 PWM: No TxA

Toggle

Autoreload RA Autoreload RB

t

C

2

0 0 0 External Event

Counter

Timer
Underflow

Pos. TxB Edge Pos. TxA

Edge

0 0 1 External Event

Counter

Timer
Underflow

Pos. TxB Edge Pos. TxA

Edge

3

0 1 0 Captures: Pos. TxA Edge Pos. TxB Edge t

C

TxA Pos. Edge or Timer
TxB Pos. Edge Underflow

1 1 0 Captures: Pos. TxA Neg. TxB t

C

TxA Pos. Edge Edge or Timer Edge
TxB Neg. Edge Underflow

0 1 1 Captures: Neg. TxA Neg. TxB t

C

TxA Neg. Edge Edge or Timer Edge
TxB Neg. Edge Underflow

1 1 1 Captures: Neg. TxA Neg. TxB t

C

TxA Neg. Edge Edge or Timer Edge
TxB Neg. Edge Underflow

Power Save Modes

The device offer the user two power save modes of opera­tion: HALT and IDLE. In the HALT mode, all microcontroller
activities are stopped. In the IDLE mode, the on-board oscil­lator circuitry and timer T0 are active but all other microcon­troller activities are stopped. In either mode, all on-board
RAM, registers, I/O states, and timers (with the exception of
T0) are unaltered.

HALT MODE

The device is placed in the HALTmode by writing a ’’1” to the
HALT flag (G7 data bit). All microcontroller activities, includ­ing the clock, and timers, are stopped. In the HALT mode,
the power requirements of the device are minimal and the
applied voltage (V

CC

) may be decreased to Vr (Vr = 2.0V)

without altering the state of the machine.

CAN HALT/IDLE mode:
In order to reduce the device overall current consumption in

HALT/IDLE mode a two step power save mechanism is
implemented on the device:

Step 1: Disable main receive comparator. This is done by

resetting both the TxEN0 and TxEN1 bits in the
CBUS register. Note: These bits should always be
reset before entering HALT/IDLE mode to allow
proper resynchronization to the CAN bus after ex­iting HALT/IDLE mode.

Step 2: Disable the CAN wake-up comparators, this is

done by resetting bit 7 in the port-m wakeup en­able register (MWKEN) a transition on the CAN
bus will then not wake the device up.

Note: If both the main receive comparator and the wake-up comparator are

disabled the on chip CAN voltage reference is also disabled. The CAN­V

REF

output is then High-Z

The following table shows the two CAN power save modes and the active CAN transceiver blocks:

Step 1 Step 2 Main-Comp Wake-Up-Comp CAN-V

REF

V

REF

Pin

0 0 on on on V

CC

/2

0 1 on off on V

CC

/2

1 0 off on on V

CC

/2

1 1 off off off High-Z

The device supports two different ways of exiting the HALT
mode. The first method of exiting the HALTmode is with the
Multi-Input Wakeup feature on the L & M port. The second
method of exiting the HALT mode is by pulling the RESET
pin low.

Since a crystal or ceramic resonator may be selected as the
oscillator, the Wakeup signal is not allowed to start the chip

running immediately since crystal oscillators and ceramic
resonators have a delayed start up time to reach full ampli­tude and frequency stability. The IDLE timer is used to gen­erate a fixed delay to ensure that the oscillator has indeed
stabilized before allowing instruction execution. In this case,
upon detecting a valid Wakeup signal, only the oscillator cir­cuitry is enabled. The IDLE timer is loaded with a value of

www.national.com 18

Power Save Modes (Continued)

256 and is clocked with the t

c

instruction cycle clock. The t

c

clock is derived by dividing theoscillator clock down by a fac­tor of 10. The Schmitt trigger following the CKI inverter on
the chip ensures that the IDLEtimer is clocked only when the
oscillator has a sufficiently large amplitude to meet the
Schmitt trigger specifications. This Schmitt trigger is not part
of the oscillator closed loop. The start-up time-out from the
IDLE timer enables the clock signals to be routed to the rest
of the chip.

The device has two mask options associated with the HALT
mode. The first mask option enables the HALTmode feature,
while the second mask option disables the HALTmode. With
the HALT mode enable mask option, the device will enter
and exit the HALT mode as described above. With the HALT
disable mask option, the device cannot be placed in the
HALTmode (writing a “1” to the HALT flag will have to effect).

IDLE MODE

The device is placed in the IDLE mode by writing a “1” to the
IDLE flag (G6 data bit). In this mode, all activity, except the
associated on-board oscillator circuitry, ad the IDLE Timer
T0, is stopped. The power supply requirements of the micro­controller in this mode of operation are typically around 30

%

of normal power requirement of the microcontroller.
As with the HALT mode, the device can be returned to nor-

mal operation with a reset, or with a Multi-Input Wakeup from
the Port L or CAN Interface. Alternately, the microcontroller
resumes normal operation from the IDLE mode when the
thirteenth bit (representing 4.096 ms at internal clock fre­quency of 1 MHz, t

c

= 1 µs) of the IDLE Timer toggles.

This toggle condition of the thirteenth bit of the IDLE Timer
T0 is latched into the T0PND pending flag.

The user has the option of being interrupted with a transition
on the thirteenth bit of the IDLE Timer T0. The interrupt can
be enabled or disabled via the T0EN control bit. Setting the
T0EN flag enables the interrupt and vice versa.

The user can enter the IDLE mode with the Timer T0 inter­rupt enabled. In this case, when the T0PND bit gets set, the
device will first execute the Timer T0 interrupt service routine
and then return to the instruciton following the “Enter Idle
Mode” instruction.

Alternatively, the user can enter the IDLE mode with the
IDLE Timer T0 interrupt disabled. In this case, the device will
resume normal operation with the instruction immediately
following the “Enter IDLE Mode” instruction.

Note: It is necessary to program two NOP instructions following both the set

HALT mode and set IDLE mode instructions. These NOP instructions
are necessary to allow clock resynchronization following the HALT or
IDLE modes.

Multi-Input Wakeup

The Multi-Input Wakeup feature is used to return (wakeup)
the device from either the HALT or IDLE modes. Alternately,
the Multi-Input Wakeup/Interrupt feature may also be used to
generate up to 7 edge selectable external interrupts.

Note: The following description is for both the Port L and the M port. When

the document refers to the registers WKEGD, WKEN or WKPND, the
user will have to put either M (for M port) or L (for port) in front of the
register, i.e., LWKEN (Port L WKEN), MWKEN (Port M WKEN).

Figures 12, 13

shows the Multi-Input Wakeup logic for the
microcontroller.The Multi-Input Wakeupfeature utilizes the L
Port. The user selects which particular Port L bit (or combi­nation of Port L bits) will cause the device to exit the HALT or
IDLE modes. The selection is done through the Reg: WKEN.
The Reg: WKEN is an 8-bit read/write register, which con­tains a control bit for every Port L bit. Setting a particular
WKEN bit enables a Wakeup from the associated Port L pin.

The user can select whether the trigger condition on the se­lected Port L pin is going to be either a positive edge (low to
high transition) or a negative edge (high to low transition).
This selection is made via the Reg: WKEDG, which is an
8-bit control register with a bit assigned to each Port L pin.
Setting the control bit will select the trigger condition to be a
negative edge on that particular Port L pin. Resetting the bit
selects the trigger condition to be a positive edge. Changing
an edge select entails several steps in order to avoid a
pseudo Wakeup condition as a result of the edge change.
First, the associated WKEN bit should be reset, followed by
the edge select change in WKEDG. Next, the associated
WKPND bit should be cleared, followed by the associated
WKEN bit being re-enabled.

An example may serve to clarify this procedure. Suppose we
wish to change the edge select from positive (low going high)
to negative (high going low) for Port L bit 5, where bit 5 has
previously been enabled for an input interrupt. The program
would be as follows:

RBIT 5, WKEN ; Disable MIWU
SBIT 5, WKEDG ; Change edge polarity
RBIT 5, WKPND ; Reset pending flag
SBIT 5, WKEN ; Enable MIWU

If the Port L bits have been used as outputs and then
changed to inputs with Multi-InputWakeup/Interrupt, a safety
procedure should also be followed to avoid inherited pseudo
wakeup conditions. After the selected Port L bits have been
changed from output to input but before the associated
WKEN bits are enabled, the associated edge select bits in
WKEDG should be set or reset for the desired edge selects,
followed by the assoicated WKPND bits being cleared.

www.national.com19

Multi-Input Wakeup (Continued)

This same procedure should be used following reset, since
the Port L inputs are left floating as a result of reset. The oc­currence of the selected trigger condition for Multi-Input
Wakeup is latched to a pending register called WKPND. The
respective bits of the WKPND register will be set on the oc­currence of the selected trigger edge on the corresponding
Port L and Port M pin. The user has the responsibility of
clearing these pending flags. Since WKPND is a pending
register for the occurrence of selected wakeup conditions,
the device will not enter the HALT mode if any wakeup bit is
both enabled and pending. Consequently, the user has the
responsibility of clearing the pending flags before attempting
to enter the HALT mode.

The WKEN, WKPND and WKEDG are all read/write regis­ters, and are cleared at reset.

PORTS L AND PORT M INTERRUPTS

Ports L and M provides the user with additional fifteen fully
selectable, edge sensitive interrupts which are all vectored
into the same service subroutine.

The interrupt from Ports L and M shares logic with the wake
up circuitry. The register WKEN allows interrupts from Port L
to be individually enabled or disabled. The registers LWKEN
and MWKEN specifies the trigger condition to be either a
positive or a negative edge. Finally, the registers LWKEN
and MWKEN latches in the pending trigger conditions.

The GIE (global interrupt enable) bit enables the interrupt
function. A control flag, LPEN, functions as a global interrupt
enable for Port Linterrupts. Setting the LPEN flag will enable

interrupts and vice versa. A separate global pending flag is
not needed since the registers LWKEN and MWKEN are ad­equate.

Since Ports L and M are also used for waking the device out
of the HALT or IDLE modes, the user can elect to exit the
HALT or IDLE modes either with or without the interrupt en­abled. If he elects todisable the interrupt, then the device will
restart execution from the instruction immediately following
the instruction that placed the microcontroller in the HALT or
IDLE modes. In the other case, the device will first execute
the interrupt service routine and then revert to normal opera­tion.

The Wakeup signal will not start the chip running immedi­ately since crystal oscillators or ceramic resonators have a fi­nite start up time. The IDLE Timer (T0) generates a fixed de­lay to ensure that the oscillator has indeed stabilized before
allowing the device to execute instructions. In this case,
upon detecting a valid Wakeup signal, only the oscillator cir­cuitry and the IDLE Timer T0 are enabled.The IDLE Timer is
loaded with a value of 256 and is clocked from the t

c

instruc-

tion cycle clock. The t

c

clock is derived by dividing down the
oscillator clock by a factor of 10. A Schmitt trigger following
the CKI on-chip inverter ensures that the IDLE timer is
clocked only when the oscillator has a sufficiently large am­plitude to meet the Schmitt trigger specifications. This
Schmitt trigger is not part of the oscillator closed loop. The
start-up time-out from the IDLE timer enables the clock sig­nals to be routed to the rest of the chip.

DS012837-13

FIGURE 12. Port M Multi-Input Wake-up Logic

www.national.com 20

Multi-Input Wakeup (Continued)

PORT M INTERRUPTS

Port M provides the user with seven fully selectable, edge
sensitive interrupts which are all vectored into the same ser­vice subroutine.

The interrupt from Port M shares logic with the wake up cir­cuitry.The MWKEN register allows interrupts from Port M to
be individually enabled or disabled. The MWKEDG register
specifies the trigger condition to be either a positive or a
negative edge. The MWKPND register latches in the pend­ing trigger conditions.

The LPEN control flag in the ICNTRL register functions as a
global interrupt enable for Port M interrupts. Setting the
LPEN flag enables interrupts. Note that the GIE bit in the
PSW register must also be set to enable these Port L inter­rupts.A global pending flag is not needed since each pin has
a corresponding pending flag in the MWKPND register.

Since Port M is also used for exiting the device from the
HALT or IDLE mode, the user can elect to exit the HALT or
IDLE mode either with or without the interrupt enabled. If the
user elects to disable the interrupt, then the device restarts
execution from the point at which it was stopped (first in­struction cycle of the instruction following the enter HALT or
IDLE mode instruction). In the other case, the device finishes
the instruction which was being executed when the part was
stopped (the NOP(Note 26) instruction following the enter
HALT or IDLE mode instruction), and then branches to the
interrupt service routine. The device then reverts to normal
operation.

Note 26: The user must place two NOPs after an enter HALT or IDLE mode
instruction.

To prevent erroneous clearing of the SPI receive FIFO when
entering HALT/IDLE mode, the user needs to enable the
MIWU on port M3. (SS) by setting bit 3 in the MWKEN reg­ister.

CAN RECEIVE WAKEUP

The CAN Receive Wakeup source can be enabled or dis­abled. There is no specific enable bit for the CAN Wakeup
feature. Although the wakeup feature on pins L0..17 and
M0..M7 can be programmed to generate an interrupt (Port L
or Port M interrupt), nointerrupt is generated upon a CAN re­ceive wakeup condition. The CAN block has it’s own, dedi­cated receiver interrupt upon receive buffer full (see CAN
Section).

CAN Wake-Up:

The CAN interface can be programmed to wake the device
from HALT/IDLE mode. This is done by setting bit 7 in the
Port M wake-up enable register (MWKEN). A transition on
the bus will cause the bit 7 of the Port M wake-up pending
(MWKPND) to be set and thereby waking up the device. The
frame on the CAN bus will be lost. The MWEDG (m port
wake-up edge) register bit 7 can be programmed high or low
(high will wake-up on the first falling edge on Rx0).

Resetting bit 7 in the MWKEN will disable the CAN wake-up.
The following sequence should be executed before entering

HALT/IDLE mode:

RBIT 7, MWKPND ;clear CAN wake-up pending
LD A, CBUS
AND A, #0CF ;resetTxEN0 and TxEN1
X A, CBUS ;disable main receive

;comparator

After the device wake-up, the CBUS bits TxEN0 and/or
TxEN1 need be set to allow synchronization on the bus and
to enable transmission/reception of CAN frames.

CAN Block Description *

This device contains a CAN serial bus interface as described
in the CAN Specification Rev. 2.0 part B.

*Patents Pending.

DS012837-14

FIGURE 13. Port L Multi-Input Wake-Up Logic

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CAN Interface Block

This device supports applications which require a low speed
CAN interface. It is designed to be programmed with two
transmit and two receive registers. The user’s program may
check the status bytes in order to get information of the bus
state and the received or transmitted messages. The device
has the capability to generate an interrupt as soon as one
byte has been transmitted or received. Care must be taken if
more than two bytes in a message frame are to be
transmitted/received. In this case the user’s program must
poll the transmit buffer empty (TBE)/receive buffer full (RBF)
bits or enable their respective interrupts and perform a data
exchange between the user data and the Tx/Rx registers.

Fully automatic transmission on error is supported for mes­sages not longer than two bytes. Messages which are longer
than two bytes have to be processed by software.

The interface is compatible with CAN Specification 2.0 part
B, without the capability to receive/transmit extended
frames. Extended frames on the bus are checked and ac­knowledged according to the CAN specification.

The maximum bus speed achievable with the CAN interface
is a function of crystal frequency, message length and soft­ware overhead. The device can support a bus speed of up to
1 Mbit/s with a 10 MHz oscillator and 2 byte messages. The
1 Mbit/s bus speed refers to the rate at which protocol and
data bits are transferred on the bus. Longer messages re­quire slower bus speeds due to the time required for soft­ware intervention between data bytes. The device will sup­port a maximum of 125k bit/s with eight byte messages and
a 10 MHz oscillator.

DS012837-16

FIGURE 14. CAN Interface Block Diagram

www.national.com 22

Functional Block Description of
the CAN Interface

Interface Management Logic (IML)

The IML executes the CPU’s transmission and reception
commands and controls the data transfer between CPU,
Rx/Tx and CAN registers. It provides the CAN Interface with
Rx/Tx data from the memory mapped Register Block. It also
sets and resets the CAN status information and generates
interrupts to the CPU.

Bit Stream Processor (BSP)

The BSP is a sequencer controlling the data stream between
The Interface Management Logic (parallel data) and the bus
line (serial data). It controls the transceive logic with regard
to reception and arbitration, and creates error signals ac­cording to the bus specification.

Transceive Logic (TCL)

The TCL is a state machine which incorporates the bit stuff
logic and controls the output drivers, CRC logic and the
Rx/Tx shift registers. It also controls the synchronization to
the bus with the CAN clock signal generated by the BTL.

Error Management Logic (EML)

The EML is responsible for the fault confinement of the CAN
protocol. It is also responsible for changing the error
counters, setting the appropriate error flag bits and interrupts
and changing the error status (passive, active and bus off).

Cyclic Redundancy Check (CRC)
Generator and Register

The CRC Generator consists of a 15-bit shift register and the
logic required to generate the checksum of the destuffed bit­stream. It informs the EML about the result of a receiver
checksum.

The checksum is generated by the polynomial:

χ

15

+

χ

14

+

χ

10

+

χ

8

+

χ

7

+

χ

4

+

χ

3

−1

Receive/Transmit (Rx/Tx) Registers

The Rx/Tx registers are 8-bit shift registers controlled by the
TCL and the BSP. They are loaded or read by the Interface
Management Logic, which holds the data to be transmitted
or the data that was received.

Bit Time Logic (BTL)

The bit time logic divider divides the CKI input clock by the
value defined in the CAN prescaler (CSCAL) and bus timing
register (CTIM). The resultig bit time (tcan) can be computed
by the formula:

Where

divider

is the value of the clock prescaler,PSis the

programmable value of phase segment 1 and 2 (1..8) and

PPS

the programmed value of the propagation segment

(1..8) (located in CTIM).

Bus Timing Considerations

The internal architecture of the CAN interface has been op­timized to allow fast software response times within mes­sages of more than two data bytes. The TBE (Transmit
Buffer Empty) bit is set on the last bit of odd data bytes when
CAN internal sample points are high.

It is the user’s responsibility to ensure that the time between
setting TBE and a reload of TxD2 is longer than the length of
phase segment 2 as indicated in the following equation:

Table 3

shows examples of the minimum required t

LOAD

for
different CSCAL settings based on a clock frequency of
10 MHz. Lower clock speeds require recalculation of the
CAN bit rate and the mimimum t

LOAD

.

TABLE 3. CAN Timing (CKI = 10 MHz, t

c

= 1 µs)

PS CSCAL CAN Bit Rate (kbit/s)

Minimum

t

LOAD

(µs)

4 3 250 2.0
4 9 100 5.0
4 15 62 8.0
4 24 40 12.5
439 25 20
499 10 50
4 199 5 100

Figure 16

illustrates the minimum time required for t

LOAD

.

DS012837-17

FIGURE 15. Bit Rate Generation

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