Go Down

Topic: ATmega328P - reset not working (Read 4 times) previous topic - next topic

JimG

Tried chip in two boards, and also tried a jumper wire touched directly to pin. No evidence of reset.  Weird, isn't it?

Jim
TC4 Open Source Digital Thermometer and Temperature Controller
http://code.google.com/p/tc4-shield

JimG

Must be a bad chip.  I put it on a breadboard and found that the problem is not that the chip doesn't reset -- it actually does respond to pulling RESET low.  The problem is that it does not restart after a reset.

To eliminate the bootloader as a variable, I burned the Blink sketch into the chip using my programmer (i.e. no bootloader).

Initiating a restart by either 1) toggling the benchtop PSU, or 2) pulling/inserting the banana plug from the PSU to the breadboard allows the Blink sketch to restart.

But if I press the Omron tactile switch (RESET to GND) on the breadboard, then Blink stops and does not restart.  Likewise, if I pull and reinsert the VCC or GND jumper wire in the breadboard rails then Blink stops and does not restart. (There is a 10K pullup on RESET).

The chip must be overly sensitive to noise on VCC, GND, or RESET.  I have a 47uF across the breadboard rails, and 0.1uF's between VCC and GND, between AVCC and AGND, and between AREF and GND.  I also have a signal diode between VCC and RESET to clamp high voltage spikes.

A different chip mounted to the same breadboard config works as expected, i.e., no problems.

Gonna toss the chip.

Jim


TC4 Open Source Digital Thermometer and Temperature Controller
http://code.google.com/p/tc4-shield

Coding Badly


On this solemn day we mourn the passing of a processor that never saw its full potential.  Struck down before it even had a chance to run Blink-Without-Delay.  We hope you find solace in Silicon Heaven.

=(

dhenry

Quote
The problem is that it does not restart after a reset.


I have (ab)used hundreds and likely a thousdand mcus and I have yet to find one that died all by itself.


JimG


On this solemn day we mourn the passing of a processor that never saw its full potential.  Struck down before it even had a chance to run Blink-Without-Delay.  We hope you find solace in Silicon Heaven.


It did run Fade before its demise ;-)

Jim
TC4 Open Source Digital Thermometer and Temperature Controller
http://code.google.com/p/tc4-shield

Go Up