Hi Everyone,
After 5 months of doing something completely different I have returned to my MOD54415 project.
In the mean time my new hardware is ready.
The hardware is specific to the application which uses the PWM outputs of the MCPWM a lot but in general it very much resembles the DEV-70 development board.
With it I am experiencing something odd which I did not have with the Dev-70 board.
The software I use simply reads the dip switches and drives a few LEDS on the base of it just like you can do on the Dev-70 board. Oddly enough though when I power up the board it does not start up (+/- 80% of the power ups).
Just like the Dev-70 board there is a reset switch and when I press that one it always boots perfectly, it never misses a beat.
I will investigate it in more detail to see what may be different between the Dev-70 and the new board but I was wandering if anybody has any suggestions ?
If I find out myself what is up I will post it because somebody else could do something with the info.
All for now.
MOD54415 Boot problems
Re: MOD54415 Boot problems
First Result: it definitely has something to do with power up behaviour:
If I apply the power by switching on the lab supply most often it does not boot.
If I leave the lab supply switched on and apply the power with a switch it never misses and always boots.
If I use the power supply ON/OFF switch to apply power but keep the reset button pressed when the power comes on it always boots as soon as I release it.
I used the DEV-70 board with a 24V DC supply and converted that down to +5V for the board. The startup behaviour was probably OK for the processor(board) so I never had a problem.
Next: do some experimenting with a resistor/capacitor combination to keep the reset line down while powering up.
If I apply the power by switching on the lab supply most often it does not boot.
If I leave the lab supply switched on and apply the power with a switch it never misses and always boots.
If I use the power supply ON/OFF switch to apply power but keep the reset button pressed when the power comes on it always boots as soon as I release it.
I used the DEV-70 board with a 24V DC supply and converted that down to +5V for the board. The startup behaviour was probably OK for the processor(board) so I never had a problem.
Next: do some experimenting with a resistor/capacitor combination to keep the reset line down while powering up.
Re: MOD54415 Boot problems
There are minimum rise times for power rails, so that might be a cause. Maybe your board needs a reset circuit that monitors the voltage rail.
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Ridgeglider
- Posts: 513
- Joined: Sat Apr 26, 2008 7:14 am
Re: MOD54415 Boot problems
Agreed 100% w/ Rnixon. Sounds like your PS comes up slowly, or that your lab supply produces some brownouts or spikes when powered on.
Re: MOD54415 Boot problems
yes, it definitely has something to do with power up behavior.
The solution I found is relatively simple: put a 1 microfarad capacitor between the reset pin and ground and it always works.
On the scope you can see the reset pin comes up +/- 1mS later and everything is fine in that case.
I have been using it that way for a few days and it has never failed to boot.
The solution I found is relatively simple: put a 1 microfarad capacitor between the reset pin and ground and it always works.
On the scope you can see the reset pin comes up +/- 1mS later and everything is fine in that case.
I have been using it that way for a few days and it has never failed to boot.