Canon imageCLASS MF8450c, Service Manual

Page: 67 / 349

Chapter 3
3-5
3.2.2 Startup Sequence
0020-8295
imageCLASS MF9170c / imageCLASS MF9150c / imageCLASS MF8450c
1. Boot Program
Executed by the CPU in the main controller PCB when the main power switch is turned on.
Check the status of the image memory (DDR-SDRAM).
Load the control program from the main program ROM to the memory if the status is normal.
Display an error code when a fault is detected.
2. Control Program 1
1) Perform checking and initialization of each device (each hardware device in the main controller PCB).
2) Perform recovery of the system file as necessary when the previous shutdown was not executed normally.
In this case, it takes longer time than a normal case to start up the program.
3) Initialize each program module.
3. Control Program 2
1) Perform initialization of each software module and communication with a printer.
2) When the printer is detected normally, the startup sequence is completed.
If it is not detected normally, an error code "E197" is displayed after a connection timeout occurs.
F-3-4
When the startup sequence is completed, it becomes possible to receive a job. (The operation screen is displayed in the control panel, and the color of the LED of
the start key is changed from red to green.)
CPU
BootROM
Main controller PCB
: access to the program at time of execution.
- When Executing the Boot Program
Main program
ROM
CPU
: access to the program at time of execution.
- When Executing the Control Program
Image memory (DDR-SD RAM)
System
area
Image data
area
Self
diagnostic
program
Boot
program
System
software
BootROM
Main program
ROM
Image memory (DDR-SD RAM)
System
area
Image data
area
Self
diagnostic
program
Boot
program
System
software