Value of internal pull-up resistor on Prop's reset line?
Rayman
Posts: 14,889
Anybody know how hard the Prop's reset line is pulled up? I don't see anything about it in the datasheet.
It's also not clear to me what the threshold voltage on RESN is... After a little playing around, I think it's not Vdd/2 like the others.
I want to add a resistor in series with the usual NPN transistor we use with the FTDI RS232RL chip to control the reset. 10k Ohm doesn't seem to work, 1k seems a little flaky, and 100 ohms seems to work fine (not totally sure though, because this testing was done in a hurry).
(Reason I'm asking is because I want to tie one of the Prop's output pins directly to the Reset pin. This way, I can programatically prevent reset. Of course, the downside is that bad programming could result in a situation where power would have to be removed to allow reset)
It's also not clear to me what the threshold voltage on RESN is... After a little playing around, I think it's not Vdd/2 like the others.
I want to add a resistor in series with the usual NPN transistor we use with the FTDI RS232RL chip to control the reset. 10k Ohm doesn't seem to work, 1k seems a little flaky, and 100 ohms seems to work fine (not totally sure though, because this testing was done in a hurry).
(Reason I'm asking is because I want to tie one of the Prop's output pins directly to the Reset pin. This way, I can programatically prevent reset. Of course, the downside is that bad programming could result in a situation where power would have to be removed to allow reset)
Comments
http://forums.parallax.com/discussion/116168/brownout-reset-behavior-and-timing
Maybe it will help.
-Phil