Motorola Commercial Series Service Information - Page 8
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3.2
Microprocessor Circuitry
The microprocessor circuitry includes microprocessor (U401) and associated EEPROM and Flash
ROM memories. The following memory IC's are used:
Reference No.
U402
U403
U404
3.2.1
Memory Usage
Radio operation is controlled by software that is stored in external Flash ROM memory (U404).
Radio parameters and customer specific information is stored in external EEPROM (U402). The
operating status of the radio is maintained in RAM located within the microprocessor. When the
radio is turned off, the operating status of the radio is written to EEPROM before operating voltage is
removed from the microprocessor.
Parallel communication with U403 and U404 is via:
address lines A(0)-A(16), from U401 port F ADDR0-ADDR13 and port G XA14-XA16
data lines D(0)-D(7), from U401 port C DATA0-DATA7
chip-select for U403, from PH6 (U401 pin 41)
chip-enable for U404, from PH7 (U401 pin 38)
output enable for U404, from PA7 (U401 pin 86)
write-enable for both U403 and U404, from PG7_R/W (U401 pin 4)
Serial communication with U402 is via:
the SPI bus
chip-select for U402, from PD6 (U401 pin 3)
3.2.2
Control and Indicator Interface
Ports PI3 and PI4 are outputs which control the top-mounted LED indicator. When PI3 is high, the
indicator is red. When PI4 is high, the indicator is green. When both are high, the indicator is amber.
When both are low, the indicator is off.
Pressing the side-mounted PTT button (S441) provides a low to port PJ0 (U401 pin 71), which
indicates PTT is asserted. Side-mounted option buttons 1 and 2 (S442 and S443) are connected to
Ports PJ6 (pin 77) and PJ7 (pin 78), respectively.
Table 1-2 Radio Memory Requirements
Description
Serial EEPROM
Static RAM
Flash ROM
Type
AT25128
(not used)
AT49LV001N_70V
THEORY OF OPERATION
Size
16K x 8
128K x 8