8-bit MicrocontrollersのトピックRe: IIC, RTI and STOP2 MC9S08QG8 Headache!

IIC, RTI and STOP2 MC9S08QG8 Headache!

Rhioponomous — Thu, 02 Apr 2009 07:40:34 GMT

Hi All,

I am trying to use the RTI, set at a 1024 ms interval, to wake up out of STOP2. When the MCU wakes up from STOP2 it sends out 2 bytes to a slave on the IIC bus and then go back to sleep in STOP2. I have it working so that I can go to sleep and wake up from STOP2 using the RTI. Separately (int another program) I have it so that I can send messages on the IIC as well as do other things in sequence (So I know it isn't stuck in the IIC write function). When I combine the STOP2 code with the IIC code I am able to write to the IIC when the first time the CPU turns on, I am then able to go into STOP2 and then 1 second later the RTI fires and I wake up. The problem then comes when I try to write to write to the IIC after waking up from STOP2. When I try to STOP into STOP2, It just hangs out in STOP2 and my RTI never triggers...

Any help would be much appreciated!

Re: IIC, RTI and STOP2 MC9S08QG8 Headache!

tonyp — Thu, 02 Apr 2009 16:33:06 GMT

Coming out of STOP2 is similar to a reset, so all peripherals must be re-initialized before using. Do you do that?

Re: IIC, RTI and STOP2 MC9S08QG8 Headache!

Rhioponomous — Tue, 07 Apr 2009 02:17:36 GMT

Thanks for your response!

I do re-initialize all peripherals after coming out of STOP2.

What is very weird is that I am able to get an ACK after I write the address byte but unable to get an ACK after I write the first byte of data after waking up from SOTP2.

What state are the pins held in during stop2? And is there a way to change that?