topic Re: 9S08GB32 reset? in 8-bit Microcontrollers

9S08GB32 reset?

BlkStang — Fri, 05 May 2006 04:36:31 GMT

MC9S08GB32CFU silicon 3L31R

Project is having apparent problems with RESET. It's possible to get the device in a weird state via external power application where the processor appears dead. If I take a voltmeter or scope probe and just touch the RESET pin (pin 1), the processor will start normally.

For low current consumption, we currently have a 330K resistor pulling RESET to Vcc. However, in trying to debug this, we substituted a 5K6 resistor with no luck. We also tried connecting a 0.1uF capacitor between the RESET pin and ground, again with no luck.

When no external power is present a 3.6V battery powers the micro through a 3.0V linear regulator. In this mode, the micro firmware tidies up and then executes a STOP instruction putting it into a STOP3 sleep. Current consumption from the battery in this mode is about 12uA which is exactly what we expected. The system is awakened by pulling IRQ low which can happen due to several events including external power being applied. If the micro is woken from sleep with the external power and then the power is removed and then re-applied in short order, the problem appears (i.e. micro apparently dead; touch reset pin and it wakes up and runs.)

I've read the 3L31R errata sheet and note that there is a RESET-related issue tantalizingly close to what we're seeing. We can also, once in a blue moon, get the thing so messed up that not only does external power have to be removed but the battery as well: That is, simply touching the reset pin doesn't help; forcing the reset pin low doesn't help; only if the power is completely removed can we get it to start again. The low-value resistor and capacitor issue mentioned on that errata sheet do not seem to help with this "sensitive" RESET pin issue we're seeing.

Any ideas?

Re: 9S08GB32 reset?

rocco — Fri, 05 May 2006 04:51:30 GMT

Hi, Blkstang:

Here is a shot in the dark:

In almost every processor I have used, I could cause those symptoms by having Vcc rise too slowly. If Vcc rises slow enough, the chip come out of reset before Vcc is within spec, and that is not a good thing. This is a situation where a capacitor is NOT your friend. When a processor gets in this state, tugging reset would always fix it.

I have found the HC08 family to be very good at powering up, which I attribute to the LVI module. But I don't have much experience yet with the HCS08 family, so I can't really say how likely it is that this is your problem.

Message Edited by rocco on 05-04-200602:53 PM

Re: 9S08GB32 reset?

byteybird9 — Fri, 05 May 2006 09:53:49 GMT

I've had a simular problem when I started using the hc05 and I'm now using it on the hc08 design that I'm working on, which is an external power-on reset. A dallus device, DS1233D, keeps the hc08 in reset for 100 milliseconds until the supply stabilizes.

I'm now having a problem under power-supply spikes where the hc08 hangs (or appears to hang). I have the COP reset in the main loop and I'm thinking that this could be a problem. My software could be looping in the main loop, resetting the COP but not performing any tasks. I'm going to set flags in the various activities that are performed every interval and then reset the COP only and if only those activites are accomplished.

Re: 9S08GB32 reset?

Alban — Fri, 05 May 2006 16:26:00 GMT

Hi,

I reported to FSL Factory Applications Engineering who hopefully will give us time to look into this.

I'll only let the board know if I get anything that helps !

Cheers,

Alban.

Re: 9S08GB32 reset?

joescott — Tue, 30 Jan 2007 20:54:57 GMT

Alban wrote:

Hi,

I reported to FSL Factory Applications Engineering who hopefully will give us time to look into this.

I'll only let the board know if I get anything that helps !

Cheers,

Alban.

Was there any answer from the FSL Factory Applications Engineering about this problem?

Regards,

Jorge

Re: 9S08GB32 reset?

Alban — Tue, 30 Jan 2007 22:46:22 GMT

Hello,

Nobody asked ever again and it seems no Service Request was put in/escalated.

Therefore I cancelled my question not to interfere with higher priority matters.

Either BlkStang found his mistake, either it wasn't a problem.

Regards,

Alban.

Re: 9S08GB32 reset?

joescott — Tue, 30 Jan 2007 23:12:19 GMT

Alban wrote:
Hello,

Nobody asked ever again and it seems no Service Request was put in/escalated.

Therefore I cancelled my question not to interfere with higher priority matters.

Either BlkStang found his mistake, either it wasn't a problem.

Regards,

Alban.

Hi,
May be helfully to know, What was BlkStang's mistake?
We already reproduce the same behavior on GB60A and GT32. Even on a Freescale Development board.

Our conclusion is that the reset PIN is extremely sensitive to EMI. So we can't make any measurement over reset's line without cause a restart. Processor manual avoid capacitors or pullup resistors so. It is a big problem for us.

Many thanks
Regards
Jorge