First let me say that what I'm trying is to learn how the things works. I know that there are several ways to upload the sketch (FTDI, cable, adapters, using a uno, etc), but, here I'm just trying to learn.
So, I got a Arduino Pro Mini, one of those generic, buy the way the programmers PIN on mini is not well defined the position, some has ground on the ends other has together, but that is not case for this topic.
So I tried to upload the sketch connecting the DTR -> DTR, TX to RX, RX to TX, and GND (this for the DB9 DTE connection which is a FTDI to RS232 cable
I powered the mini using a 9V battery on RAW/GND connector as the FDTI to RS232 don't provide 5V
Then I tried to upload the sketch choosing Arduino Pro/Mini and 5v 328P, and it failed.
So to debug I removed the chip from a Uno that I have and just connected it to the mini on the same way, of course not crossing the TX/RX and connect RESET from uno to DTR on Mini, and it worked
I went investigated a little more and connected my Saleae logic analyzer to see the signals, and what I discovered was that while while using the UNO+Mini the TX/RX was at high level when doing nothing, and going LOW to represent bit 1, and on the FTDI -> RS232 the TX/RX was LOW when doing nothing and going HIGH to represent 1 (what is called Signal Inversion on the Saleae logic analyzer)
Any idea who control the set of RS232 on the computer to set it as regular RS232 (HIGH to represent 0). I had a look on the properties of RS232 port but just found the regular rate, parity etc, but nothing about Signal Inversion.
Any idea?
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