what's different between immediate mode and shadow mode

li jang-ya said:

i want to know what's different between immediate mode and shadow mode , and why shadow mode is recommended to use

finally , what application is need to immediate mode

 

Immediate mode means whatever value you wrote takes effect at that very moment.  Shadow mode means it will not take effect until some defined time - for example, when a timer is equal to zero.

-Lori

thanks for your reply

i tried the immediate mode on pwm yesterday , but sometimes it seems wrong

for example: I write the value1850 to CMPA, it should get 50% duty cycle, but it become about 90%

if i use shadow mode the duty cycle is right

why the immediate is wrong??