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ST92F124/F150/F250 - GENER AL DESCRIPTION
1.2 PIN DESCRIPTI ON
AS
. Address Strobe (output, active low, 3-state).
Address Strobe is pulsed low o nce at the beginning of each memory cycle. The rising edge of AS
indicates that address, Read/Write (RW), and
Data signals are valid for memory transfers.
DS
. Data Strobe (output, active low, 3-state). Data
Strobe provides the timing for data movement to or
from Port 0 for each memory transfer. During a
write cycle, data out is valid at the leading edge of
DS
. During a read cycle, Data In must be valid pri-
or to the trailing edge of D S
. When the ST9 ac-
cesses on-chip memory, DS
is held high during
the whole memory cycle.
RESET
. Reset (input, active low). The ST 9 is ini-
tialised by the Reset signal. Wi th the d eactivation
of RESET
, program execution begins from the
Program memory location pointed to by the vector
contained in program memory locations 00h and
01h.
RW
. Read/Write (output, 3-state). Read/Write de-
termines the direction of data transfer for external
memory transactions. RW
is low when writing to
external memory, and high for all other transactions .
OSCIN, OSCOUT. Oscillator (input and output).
These pins connect a pa rallel-resonant crystal, or
an external source to the on-chip clock oscillator
and buffer. OSCIN is the input of the os cillator inverter; OSCOUT is the output of the oscillator invert er .
HW0SW1. When connect ed to V
DD
through a 1K
pull-up resistor, the software watchdog option is
selected. When connected to V
SS
through a 1K
pull-down resistor, the hardware watchdog option
is selected.
VPWO. This pin is the output line of the J1850 peripheral (JBLPD). It is available only on some devices.
RX1/WKUP6. Receive Data input of CAN1 and
Wake-up line 6. Available only on some devices.
When the CAN1 peripheral is disabled, a pull-up
resistor is connected internally to this pin.
TX1. Transmit Data ou tput of CAN1. A vailable on
some devices.
P0[7:0], P1[7:0] or P9[7:2]
(Input/Output, TTL or
CMOS compatible)
. 11 lines (64-pin devices) or 22
lines (100-pin devices) providing the external
memory interface for addressing 2K or 4M bytes of
exte r nal memory.
P0[7:0], P1[2:0], P2[7:0], P3[7:4], P4.[7:4],
P5[7:0], P6[5:2,0], P7[7:0]
I/O Port Lines (Input/
Output, TTL or CMOS compatible)
. I/O lines
grouped into I/O ports of 8 bits, bit programmable
under software control as general purp ose I/O or
as alternate functions.
P1[7:3], P3[3:1], P4[3:0], P6.1, P8[7:0], P9[7:0]
Additional I/O Port Lines available on 100-pin versions only.
P3.0, P6[7:6]
Additional I/O Port Line s available
on ST92F250 version only.
AVDD. A nalog VDD of the Analog to Digital Con-
verter (common for ADC 0 and ADC 1).
AVDD can be switched off when the ADC is not in
use.
AV
SS
. Analog VSS of the Analog t o Digital Con-
verter (common for ADC 0 and ADC 1).
V
DD
. Main Power Supply Voltage. Four pins are
available on 100-pin versions, two on 64-pin versions. The pins are internally connected.
V
SS
. Digital Circuit Ground. Four pins are ava ila-
ble on 100-pin v ersions, two on 64-pin v ersions.
The pins are internally connected.
V
TEST
Power Supply Voltage for Flash test pur-
poses. This pin must be kept to 0 in user mode.
V
REG
. Stabilization capacitors for the internal volt-
age regulator. The user must connect external stabilization capacitors to these pins. Refer to
Figure
16.
1.2.1 Electromagnetic Compatibility (EMC)
To reduce the electromagnetic interference the following features have been implemented:
– A low power oscillator is included with a control-
led gain to reduce EMI and the power consumption.
– Two or Four pairs of digital power supply pins
(V
DD
, VSS) are located on each side of the 100-
pin package (2 pairs on 64-pin package).
– Digital and analog power supplies are complete-
ly separated.
– Digital power supplies for internal logic and I/O
ports are separated internally.
– Digital power supplies managed by Internal Volt-
age Regulator
Note: Each pair of d igital V
DD/VSS
pins should be
externally connected by a 10 µF tanta lum capacitor and a 100 nF ceramic capacitor.
1.2.2 I/O Port Alternate Functions
Each pin of the I/ O ports of the ST92F124/F150/
F250 may assume software programmabl e Alternate Functions as shown in Section 1.4.
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