I have a nagging problem that I just can't seem to solve. I have a standalone ATMega328P on a custom PCB that is bootloaded with Optiboot so I can use the Arduino IDE to program it thru a FT232RL. I'm now trying to get a Software Serial port to send some data back to me but I just can't get it working. The Software serial, from what I can see works. When I hook up an Oscilloscope to the TX pin, I can see it "talking" @ ~3.3V. In the end I will need to convert this to 12V serial levels, so another computer can receive data from it. I've read that the Max232 or Max3232 should do that, so I bought these: http://www.ebay.com/itm/310624019670?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT http://www.ebay.com/itm/401087384806?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
However, no matter how I hook either of these to the TX Pin of the Software Serial, I just don't see any signal with the oscilloscope.
The first step goal will be to connect the software serial back to the PC using a serial to USB converter and seeing if the sent data is received correctly.
So my questions are now: Has anybody already done such a thing and can maybe provide a schema or something that shows how exactly this is done? I think I need a Max232CPE to do the conversion, is that correct? Since another PC needs to read data sent from the ATMega, would I be better off using e.g. a ATMega644 with 2 hardware serial ports? Or would software Serial be sufficient? (Transmittion rate is 9600baud and there are a couple of bytes to send every second.
Thanks a lot for any help on this, I'm starting to pull my hair with this problem. Martin