HCS08: STOP1 mode

[marcom]

Hi,

this is the problem.

I put in STOP1 mode HCS08. If I put it debugging (InDart tool) is all ok; program go to STOP instruction and say that MCU is in STOP mode.

If I run the same program without debugger, after STOP instruction, MNCU reset itself and begin again ....

Please note:

Watchdog (COP) is disable

RTI is disable

STOPE is enable.

LVD is disable in stop mode

Reset pin is disasble and external pull up tu VDD.

At startup I read SRS and SPMSC2 PDF bit.

I read, that MCU exit from a STOP1 as expected and the RESET was a power on reset !!!!!

Please, help me: I don't know the reason of this Power on reset after STOP1.

[marcom]

Hi Rocky,

on MC9S08QG4CDT IRQ# and RESET# are shared on the same pin; I have pulled up to 3.3V.

I'm debugging and I expect that if I put micro in STOP1 mode, it wake up itself  not for ever. Obvously, in normnal operation, I will wake up with an IRQ or external RESET..... 

[RockyRoad]

marcom -

A power on reset is the normal exit from STOP1. I guess that you're not expecting an exit from STOP1.

A possible cause is that on some S08's, like the GB-family, the IRQ does not have an internal pullup in STOP and will be low. This will cause an immediate exit from STOP1. You took care of the reset pin, but the IRQ may need an external pullup resistor also.

- Rocky