Gp 13 Circuit Operation - Xerox WorkCentre M20 Service Manual

GP 13 Circuit Operation

Purpose
To give information about the operation of the machines circuitry:
• Power On/Off Reset
• Program ROM (Flash Memory) Control
• AC Characteristics
• USB (Universal Serial Bus)
• SRAM
• FAX
NOTE: If necessary, refer to GP 20 for the acronym list and cross reference lists of more com-
monly recognised part names.
Power On/Off Reset
Signal Operation
Input signal: +3.3V Power Line (VCC)
Output Signal: XC61 FN 3112 (POWER ON/OFF DETECT VCC RISING/FALLING 3.1V
RESET TIME (Td): 5.461ms
Timing Chart
Refer to Figure 1.
Figure 1 Timing chart
General Procedures and Information
GP 13
Program ROM (Flash Memory) Control
Device
Refer to Table 1.
M20F
TYPE NO. AM29LU160DB
CAPACITY 4 MBYTE (1M * 16BITS * 2) 16MB (8MB x 2ea)
Programming
Refer to Table 2.
BEFORE ASS'Y EPROM PROGRAMMER or PROGRAMMING at the factory
AFTER ASS'Y DOWNLOAD from PC
Operating Principle
When the RCSO (ROM CHIP SELECT) signal is activated from the CPU after the POWER is
ON, it activates RD SIGNAL and reads the DATA (HIGH/LOW) stored in the FLASH MEMORY
to control the overall system. The FLASH MEMORY may also write. When turning the power
on, press and hold the key (power switch) for 2 to 3 seconds, then the LED will scroll and the
PROGRAM DOWNLOAD MODE will be activated. In this mode, you can download the pro-
gram through the parallel port.
December 2006
6-44
Table 1 Device
4118 2218
29GL064M90TFIR40 S29GL064M90TFIR40
16MB (8MB x 2ea)
Table 2 Programming
WorkCentre M20, 4118, FaxCentre 2218 Family