Strange Propeller behavior

rkrasowski

Hello,
that happened to me few times. I am connecting GPS with MAX 232, as well as 3 axis accelerometer to my Propeller board. When I do that I can not communicate with Propeller. It is not recognized on its port by propeller toolkit. When I disonnect power from GPS or Max232 things are normal again. At the same time everything else seems to working properly with everything powered up. Data are read from GPS, send to serial port SD card etc.
Any ideas??

Mike Green

You didn't give much information, so it's hard to be specific. Most likely you have some kind of power problem, perhaps when you have both the MAX232 and the GPS, the total amount of current drawn is too high for the regulator on the Propeller board. The MAX232 doesn't draw much current, so that's a bit odd, but the Propeller has to be powered up and operating off its internal clock for it to be recognized by the Propeller Tool.

If you want to pursue this further, you really have to describe your whole setup, what's connected to what, etc.

rkrasowski

Thanks Mike for answer, that what may be a problem with current, but here is my setup:
As a prototype board is use :Propeller education kit
For 5V power - LM 2940 - ( from the kit)
I do take that power to GPS (ER411 - GlobalSat ) - measured current - 38-39mA
and MAX232 - measured current 5.2 mA
So it is not that much to create the problem (??). For now to program I simply disconect GPS and MAX, but it is strange.
Interesting that after downloading I connect everything, plus XBee and thing is working like a charm
Thanks
Robert

rkrasowski

Well, it is dumm what I did, and the reason for my problem, but I think that can be education for other members.
TTL level output from my GPS (after passing via MAX232) was going into pin 31, yes and that is the problem - that is the same pin that Propeller use to comunicate with laptop and Propeller Tool.
Now I changed that pin to 27 and everything is working properly.
Silly error cost me 2h to solve.
Thanks for help
Robert