Re: Uploading the Software

Posted by homerisback on Jul 13, 2017; 7:32am
URL: http://bluesaab-forum.90.s1.nabble.com/Uploading-the-Software-tp235p1127.html

Hi,
When building this BlueSAAB version I struggled a lot like you. I had never been able to use my FTDI cable which was a 3V3 : really unsufficient power in to have a proper 3V3 on board after voltage regulator. A good 5V is really better, at 3V3, the regulator goes really hot ! I got rid of this cable and went to UART programming and used Arduino UNO as ISP to handle the whole programming job.
First, I removed the Atmega from BlueSAAB and pulled RN52's GPIO9 down (RN52 going to CMD mode) by putting a wire between PIN 6 of atmega328 socket and board's GND (that's why Atmega is removed)
I also soldered a small piece of metal between GPIO7 and closest GND pin on RN52 (this forces it to be constantly @9600 bds and avoids any mis-communication in case of factory reset (SF,1)...)
I connected the BlueSAAB and Arduino UNO like this :
Arduino UNO                                   BlueSAAB 3.2
5V output ----------------------------->   FDTI 3V3 input
GND output --------------------------->   FDTI GND
~5 PWM  ------------------------------>  UART RX
~6 PWM  ------------------------------>  UART TX
ArduinoISP sketch is uploaded into Arduino Uno board.

From here, I was able to communicate with RN52 via serial monitor in Arduino IDE software. I sent the whole batch of commands and could check the proper pairing and comms with my bluetooth device.

After all this, Atmega328 is put back on BlueSAAB board and the Arduino uno (as ISP) is used to upload SAAB-CDC.ino code. Same connections between boards and using "Atmega328 on a breadboard" as device in Arduino IDE software and "upload with a programmer" option.
Either, put the Atmega328 on Uno board and upload the code directly... maybe faster and easier.

Having done all this, with Atmega328 back on board, it should work...
That's the strongest and reliable way I was able to have 3.2 working flawlessly ;)

Good luck !