Harry Liu

DEMOJM Board USB Resume Issue

Discussion created by Harry Liu on Aug 13, 2012

I am using MC9S08JM60 with DEMOJM board. It seems there is a problem with HID mouse example code in the disk.


HID mouse code works well when I connect the board to PC. But if I set PC to standby mode and then back to normal mode, device is not resumed successfully. Digged into the code, I found that MCU went back to STOP3 mode after failed waiting for RESUMEF which is supposed to be valid at that time. After that MCU will never come back to normal mode. Onlyl if I change the code to not go to STOP3 mode again if the RESUMEF is not valid, then it works.


I have also measured the external clock signal. When the USB resume signal triggered MCU from STOP3 to normal mode, there is no output from external clock. I guess MCU went to STOP3 mode again before successfully switch clock.


What caused USB resume fail? Is it because of the clock issue? How to solve this properly?