MX COM Inc MX429AJ, MX429ALH, MX429AP Datasheet

DATA BULLETIN

MX429A

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

1200/2400bps MSK Modem

for Trunked Radio Systems

Features



Band III & General Purpose Trunked Radio Apps



Full-Duplex 1200 and 2400 Baud Operation



Error Check Word Generation and Checking



Preamble Generation



µProcessor Compatible Interface



Frame SYNC and SYNT Detection



Low Power Consumption



General Purpose Timer

CARRIER DETECT

TIME CONSTANT

MSK

RECEIVER

RX CARRIER

DETECT

SYNC/SYNT DETECTOR

BYTE

COUNTER

CHECKSUM

CHECKER

RX DATA

RX DATA BUFFER

8-BIT uP BUS

CLOCKS

CLOCK

GENERATORS

TIMER

CONTROL REGISTER

TX DATA BUFFER

TX DATA

BYTE

COUNTER

CHECKSUM

GENERATOR

MSK

TRANSMITTER

INTERRUPT

GENERATOR

DAT A

1200/ BAUD2400

XTAL/CLOCK

XTAL

1.008 MHz OUTPUT

STROBE

WR/ A1 A0 D7 D6 D5 D4 D3 D2 D1 D0

MICROPROCESSOR

INTERFACE

RECOVERED CLOCK

RX MESSAGE FORMAT RX CHECKSUM TRUE

BIAS

STATUS

SYNC SYNT RX DATA READY RX CARRIER DET. RX CHECKSUM TRUE TX DATA READY TX IDLE TIMER EXPIRED

TX PARITY ENABLE

TRANSMITTER

OUTPUT

IRQ

RX DATA RDY TX DATA RDY

SYNC

SYNT

TX IDLE

RX ENABLE TX ENABLE RX MESSAGE FORMA T TX PARITY ENABLE

RECEIVER INPUT

The MX429A is a single-chip CMOS 1200 and 2400 baud MSK modem, designed primarily for use in Trunked Radio Systems but may also be employed in other general purpose radio or line data communication applications. The device has been designed to conform to the UK Band III trunked radio protocols MPT 1317/1327.

The MX429A is full duplex at 1200 and 2400 baud and includes an 8-bit parallel microprocessor interface and a programmable timer which may be set for interrupt periods of 8 to 120 bits. Preamble may be generated by the device in transmit. The 16-bit SYNC or SYNT words are detected in receive. An error check word is automatically generated in transmit and error checking is performed in the receive mode. An on-chip Xtal/clock generator requiring an external 4.032MHz Xtal or clock input provides both 4.032MHz and

1.008MHz outputs and performs all modem timings. The MX429A requires a single 5-volt power supply, has a powersave facility, and is available in the following

package styles: 24-pin CDIP (MX429AJ), 24-pin PDIP (MX429AP), and 24-pin PLCC (MX429ALH).

1200/2400bps MSK Modem for Trunked Radio Systems 2 MX429A

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

CONTENTS

Section Page

1 Block Diagram.................................................................................................................3

2 Signal List........................................................................................................................3

3 External Components.....................................................................................................5

4 General Description........................................................................................................6

4.1 Modems in Mobile Data Signaling.......................................................................................... 6

4.1.1 Digital Code Format....................................................................................................................6

4.1.2 Operation....................................................................................................................................6

4.1.3 Non MPT Application – Full-Duplex..........................................................................................7

4.1.4 Control Register (A1 = 1, A0 = 1,

WR/

= 0, Write Only)...........................................................7

4.1.5 Status Register (A1 = 1, A0 = 1,

WR/

= 1, Read Only)............................................................8

4.1.6 Rx Data Buffer (A1 = 1, A0 = 0,

WR/

= 1, Read Only).............................................................9

4.1.7 Tx Data Buffer (A1 = 1, A0 = 0,

WR/

= 0, Write Only)..............................................................9

4.2 Syndrome Word.................................................................................................................... 10

4.2.1 Syndrome Low Byte (A1 = 0, A0 = 0,

WR/

= 1, Read Only) ..................................................10

4.2.2 Syndrome High Byte (A1 = 0, A0 = 1,

WR/

= 1, Read Only)..................................................10

4.3 Carrier Detect Time Constant............................................................................................... 10

5 Application ....................................................................................................................11

5.1 Checksum Generation and Checking................................................................................... 11

5.2 Receive Operation................................................................................................................ 11

5.3 Transmit Operation............................................................................................................... 12

5.4 Basic Power Up Software..................................................................................................... 13

5.5 Basic Software Interrupt Flow............................................................................................... 14

5.6 Bus Interface Timing............................................................................................................. 15

5.6.1 Bus interface design migration from MX429 to MX429A..........................................................15

6 Performance Specification...........................................................................................15

6.1 Electrical Performance ......................................................................................................... 15

6.1.1 Absolute Maximum Ratings......................................................................................................15

6.1.2 Operating Limits .......................................................................................................................15

6.1.3 Operating Characteristics.........................................................................................................16

6.1.4 Timing.......................................................................................................................................18

6.2 Packaging............................................................................................................................. 18

MX•COM, Inc. reserves the right to change specifications at any time and without notice.

1200/2400bps MSK Modem for Trunked Radio Systems 3 MX429A

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

1 Block Diagram

CARRIER DETECT

TIME CONSTANT

MSK

RECEIVER

RX CARRIER

DETECT

SYNC/SYNT

DETECTOR

BYTE

COUNTER

CHECKSUM

CHECKER

RX DATA

RX DATA BUFFER

8-BIT uP BUS

CLOCKS

CLOCK

GENERA TORS

TIMER

CONTROL

TX DATA BUFFER

TX DATA

BYTE

COUNTER

CHECKSUM

GENERA TOR

MSK

TRANSMITTER

INTERRUPT

GENERA TOR

DAT A

1200/ BAUD2400

XT AL/CLOCK

XT AL

1.008 MHz OUTPUT

STROBE

WR/ A1 A0 D7 D6 D5 D4 D3 D2 D1 D0

MICROPROCESSOR

INTERFACE

RECOVERED CLOCK

RX MESSAGE FORMAT

RX CHECKSUM TRUE

BIAS

ST ATUS

SYNC SYNT RX DATA READY RX CARRIER DET. RX CHECKSUM TRUE TX DATA READY TX IDLE TIMER EXPIRED

TX P ARITY ENABLE

TRANSMITTER

OUTPUT

IRQ

RX DAT A RDY TX DAT A RDY

SYNC SYNT

TX IDLE

RX ENABLE TX ENABLE RX MESSAGE FORMAT TX PARITY ENABLE

RECEIVER INPUT

Figure 1: Block Diagram

2 Signal List

Pin No. Signal Description

J/P LH Name Type

11 V

BIAS

The internal circuitry bias line, held at VDD/2 this pin must be decoupled to V

by a capacitor, see Figure 2.

2 2 Transmit Output Output The 1200 baud, 1200Hz/1800Hz and 2400 baud, 1200Hz/2400Hz

MSK Tx output. When not enabled by the Control Register (D0) its output impedance is set high.

3 4 Receiver Input Input The 1200/2400 baud received MSK signal input. The

1200Hz/1800Hz, 1200Hz/2400Hz audio to this pin must be ac coupled via a capacitor, see Figure 2.

55 V

Power Positive Supply. A single +5V regulated supply is required. It is

recommended that this power rail be decoupled to V

by a

capacitor, see Figure 2.

6 6 Carrier Detect

Time Constant:

The on-chip Carrier Detect function requires external component(s) on this pin. See Figure 2for recommended component(s).

7 7 Xtal/Clock The input to the clock oscillator inverter. A 4.032 MHz Xtal or

externally derived clock pulse input should be connected here, see Figure 2.

XTAL

The output of the 4.032 MHz clock oscillator.

1200/2400bps MSK Modem for Trunked Radio Systems 4 MX429A

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Pin No. Signal Description

J/P LH Name Type

99 D0 10 10 D1 11 11 D2 Microprocessor Data Interface 12 12 D3 These 8 lines are used by the device to communicate with a

micro-

13 13 D4

processor with the R/

W , A0 and A1 inputs determining register

selection. 14 14 D5 15 15 D6 16 16 D7 17 17 A0

W input, select the 18 18 A1 required register to the data bus as shown in Table 2 19 19

STROBE

Performs the dual functions of selecting the device for Read or Write and strobing data in or out. It should be generated by gating the high order address bits with a Read/Write clock. The MX429A is selected when this pin is a logic ‘0’.

20 20

Used in conjunction with A1 and A0 to determine which internal registers are connected to the data interface pins (D0 to D7) during Strobe.

21 21

IRQ

Interrupt Request. This line will go to a logic '0' when an interrupt occurs. This output can be "wire OR'd" with other active low components (100kW pullup to V

). The conditions that cause

the interrupts are indicated at the Status Register and are as follows: Timer Expired, Rx Data Ready, Tx Data Ready, Tx Idle, Rx SYNC Detect, Rx SYNT Detect

22 24

Baud 2400/1200

Select

A logic ‘1’ on this pin selects the 1200 baud option. Tone frequencies are: one cycle of 1200Hz represents a logic ‘1’, one and a half cycles of 1800Hz represents a logic ‘0’. A logic ‘0’ on this pin selects the 2400 baud option. Tone frequencies are: one half cycle of 1200Hz represents a logic ‘1’, one cycle of 2400Hz represents a logic ‘0’. This pin has an internal 1M pullup resistor.

23 22 V

Power Negative Supply (GND)

24 23 Clock/4 A 1.008 MHz (X1 ÷ 4) clock is available at this output for external

circuit use, note the source impedance and source current limits.

4 3 Leave this pin open-circuit

Table 1: Signal List

A0 A1

Control 0 1 1 Status 1 1 1 Rx Data 1 0 1 Tx Data 0 0 1 Syndrome Low 1 0 0 Syndrome High 1 1 0

Table 2: Register Selection

1200/2400bps MSK Modem for Trunked Radio Systems 5 MX429A

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

3 External Components

MICROPROCESSOR DATA INTERFACE

D1 D2

D5D5D6

TRANSMIT OUTPUT

RECEIVE INPUT

'CD' TIME CONSTANT

XTAL/CLOCK

CLOCK/4

1200/ BAUD SELECT2400

BIAS

Xtal/Clock

MX429A

XTAL

Recommended Xtal

Component

24 23 22

20 19

18 17

16 15 14 13

D1 D2 D3

XTAL

1 2 3 4 5

6 7

8 9

STROBE

R/W

IRQ

Figure 2: Recommended External Components



10%

1.0F



20%



10%

1.0F



20%

C1 33pF



20%

1.0F



20%

C2 33pF



20%

0.1F



20%

X1 Note 1 4.032MHz

Table 3: Recommended External Components

Notes:

1. For best results, a crystal oscillator design should drive the clock inverter input with signal levels of at least 40% of VDD, peak to peak. Tuning fork crystals generally cannot meet this requirement. To obtain crystal oscillator design assistance, consult your crystal manufacturer.

1200/2400bps MSK Modem for Trunked Radio Systems 6 MX429A

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

4 General Description

4.1 Modems in Mobile Data Signaling

4.1.1 Digital Code Format

The MPT 1327 Signaling Standard for Trunked LMR Systems protocol is used by the MX429 for communication between a Trunking System Controller (TSC) and users' radio units. These data stream formats are summarized in Figure 3.

Preamble SYNC or SYNT

For bit sync. SYNC Word Address Code

101010...10..- bit reversals 1100010011010111 Word Optional Data

Minimum 16 bits, ending in SYNT Word Code Words

logic'0' 0011101100101000 64 Bits

Address Code Word Structure

(Bit number 1 is transmitted first) Bit No. No.of Bits

Bit Name

1 1

Logic '1'

2 to 8

User Identity

9 to 48

Address

Data

49 to 64

Check Bits

(Checksum)

Figure 3: Tx and Rx Data Stream

4.1.2 Operation

The MX429A can be used for Full-Duplex operation with the host microprocessor only having to operate on the data while the modem (MX429A) handles all other signaling routines and requirements.

In the Tx mode the MX429A will :

1. Internally generate and transmit a preamble – bit reversals, for system bit synchronization.

2. Accept from the host, and transmit, a 16-bit 'SYNC' or 'SYNT' word.

3. Accept from the host, and transmit, 6 bytes of data (Address Code Word): A. Upon a software command, internally calculate and transmit a 2-byte checksum based on the

previous 6 data bytes.

B. Upon a software command, disable internal checksum generation and allow continuous data

transmission.

4. Transmit 1 'hang bit' and go idle when all loaded data traffic has been sent (followed by a "Tx Idle" interrupt).

In the Rx mode the MX429A will:

1. Detect and achieve bit synchronization within 16 bits.

2. Search for and detect the 16-bit 'SYNC'/'SYNT' word.

3. Output all received data after 'SYNC/SYNT,' in byte form.

4. Upon a software command (Rx Message Format), use the received checksum to calculate the presence (if any) of errors, and advise the host with an interrupt and a 16-bit Syndrome word.

Note: In Rx, a software command is used to determine whether a 'SYNC'/'SYNT' word is required after

every 8 (6 data + 2 checksum ) received bytes, or "data" is received continually. Normally the 'SYNC' word is used on the Control data channel and the 'SYNT' word is used on the Traffic data channel.

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MX COM Inc MX429AJ, MX429ALH, MX429AP Datasheet

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