Propeller demo board won't read from eeprom without USB being attached

Red_Dog

I have a propeller demo board and just recently realized that it won't load and run a program from eeprom unless attached to the computer's USB port. The propeller tool doesn't need to be running, I think it just needs USB power. Is this normal behavior for the demo board or have I blown something? I usually just write to RAM, but now have a project where I want it to start up and do its thing when I turn on the power.

Thanks in advance,

Red_Dog

max72

this is probably the ftdi reset.
If you have a serial console on the terminal, it will reset the prop if the usb is not connected.
if you are using propeller serial terminal OBC created a pst dummy object. Simply place it in the same director, modify the object name, and the console is not used. no need to comment out the pst calls.
No more resets.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDgQFjAA&url=http%3A%2F%2Fforums.parallax.com%2Fattachment.php%3Fattachmentid%3D70219%26d%3D1273608817&ei=VEvNUo60CoX_ygOKxYDYCQ&usg=AFQjCNHKezANqEaRFaQHlSfngyyTcAVe9A&sig2=UI3K0Rc-9a4lmAi0SCdwrg&bvm=bv.58187178,d.bGQ&cad=rja

Red_Dog

Thanks max27. As soon as I saw your post I remembered using the pst to look at a counter while doing some testing. Forgot to go back and remove the code when I was finished and completely forgot it was there.

thanks again,

Red_dog

Sapphire

I recently came across this problem when I disconnected the USB cable from a Propeller Demo Board (PDB), and the program wouldn't run. I had not seen this before, probably because I always had the USB cable plugged in.

But removing the PST output to the USB port is not desirable, as I write some diagnostics and a banner line on startup, so I know what version is running.

I don't have this problem with the Propeller Professional Development Board (PPDB), and it uses the same FT232RQ chip according to the schematic. The only difference I can see is that the PPDB has a 33k pulldown resistor at the base of the reset transistor, and the PDB has a 10k pulldown resistor. Is this what is causing the problem on the PDB? Would replacing the 10k resistor with a 33k resistor fix it?

Duane Degn

I doubt switching the resistor value would fix the reset issue on the Demo Board. I don't know why the PPDB doesn't reset but I don't think the only difference is the pull-down resistor (though I'm not sure about this). It's possible the FTDI chip on the two boards were programmed differently.

I don't know if you've seen this thread or not but it lists a couple different options.

I didn't see it mentioned in the above thread, but one option is to monitor the rx line to see if it's "live" when the program starts. If the line isn't active, the program sets a flag and doesn't use any of the debug statements.

Sapphire

Thanks Duane. Your link to that thread explains a lot, and you gave me a way around this problem by monitoring P30 at reset and not activating the serial output if the USB is not connected. Much appreciated.