Re: power on reset prob

Started by Stewart Prince November 21, 2003
Yes, I did put the RC filter between the 34064 and the reset pin on the
D60A. That's how they show it in the 34064 data sheets. However, now I
see the error of my ways.....the RC filter is pulled low by the BDM pod,
which then tries to write to the microprocessor, which is still being
reset by the RC filter!! Well, we can't change this version of the
board as it is already in our Mechatronics lab and we're getting ready
for the spring semester, but the next generation will have the 809 or
equivalent reset circuit. I'll just remove the capacitor from the circuit.

Many thanks to all
Stewart Prince
Professor, Mech Eng
CSUN

Oliver Betz wrote:

>Stewart Prince <> wrote: >
>>In order to overcome any problems with the oscillator not starting up
>>before the power on reset occurs, we connected a 3406 supervisor IC to
>>the reset line of a D60a in conjunction with an RC filter of 50 ms to
>>make sure the oscillator has enough time to oscillate properly. When
>>
>>
>
>What do you mean writing "in conjunction with an RC filter": did you
>filter the supply of the 34064? This should work. Putting the RC
>filter on the Reset line doesn't work, as Gordon wrote.
>
>BTW: I suggest the MAX809-type reset ICs since they are much cheaper
>and available from many manufacturers. They have a push-pull output,
>but you can use a series resistor between the *809 output and the
>/Reset line _instead_ (!) of the usual pullup resistor. This works
>fine as long as there are no other pull-up devices connected to the
>/Reset line.
>
>Oliver