Serial Peripheral Interface (Spi); Sbep Serial Interface; General Purpose Input/Output - Motorola CM160 Service Information

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5.5

Serial Peripheral Interface (SPI)

The µP communicates to many of the IC's through its SPI port. This port consists of SPI TRANSMIT
DATA (MOSI) (U403-pin100), SPI RECEIVE DATA (MISO) (U403-pin 99), SPI CLK (U0403-pin1)
and chip select lines going to the various IC's, connected on the SPI PORT (BUS). This BUS is a
synchronous bus, in that the timing clock signal CLK is sent while SPI data (SPI TRANSMIT DATA
or SPI RECEIVE DATA) is sent. Therefore, whenever there is activity on either SPI TRANSMIT
DATA or SPI RECEIVE DATA there should be a uniform signal on CLK. The SPI TRANSMIT DATA
is used to send serial from a µP to a device, and SPI RECEIVE DATA is used to send data from a
device to a µP.
There are two IC's on the SPI BUS, ASFIC CMP (U504 pin 22)), and EEPROM (U400). In the RF
sections there is one IC on the SPI BUS, the FRAC-N Synthesizer. The chip select line CSX from
U403 pin 2 is shared by the ASFIC CMP and FRAC-N Synthesizer. Each of these IC's check the
SPI data and when the sent address information matches the IC's address, the following data is
processed.
When the µP needs to program any of these Is it brings the chip select line CSX to a logic "0" and
then sends the proper data and clock signals. The amount of data sent to the various IC's are
different; e.g., the ASFIC CMP can receive up to 19 bytes (152 bits). After the data has been sent
the chip select line is returned to logic "1".
5.6

SBEP Serial Interface

The SBEP serial interface allows the radio to communicate with the Customer Programming
Software (CPS), or the Universal Tuner via the Radio Interface Box (RIB) or the cable with internal
RIB. This interface connects to the SCI pin via control head connector (J2-pin 17) and to the
accessory connector P1-6 and comprises BUS+. The line is bi-directional, meaning that either the
radio or the RIB can drive the line. The µP sends serial data and it reads serial data via pin 97.
Whenever the µP detects activity on the BUS+ line, it starts communication.
5.7

General Purpose Input/Output

The controller provides six general purpose lines (PROG I/O) available on the accessory connector
P1 to interface to external options. Lines PROG IN 3 and 6 are inputs, PROG OUT 4 is an output
and PROG IN OUT 8, 12 and 14 are bi-directional. The software and the hardware configuration of
the radio model define the function of each port.
• PROG IN 3 can be used as external PTT input, or others, set by the CPS. The µP reads this
port via pin 72 and Q412.
• PROG OUT 4 can be used as external alarm output, set by the CPS. Transistor Q401 is
controlled by the µP (U403 pin 55)
• PROG IN 6 can be used as normal input, set by the CPS. The µP reads this port via pin 73
and Q411. This pin is also used to communicate with the RIB if resistor R421 is placed.
• DIG IN OUT 8,12,14 are bi-directional and use the same circuit configuration. Each port uses
an output Q416, Q404, Q405 controlled by µP pins 52, 53, 54. The input ports are read
through µP pins 74, 76, 77; using Q409, Q410, Q411
THEORY OF OPERATION