On Fri, Oct 2, 2015 at 10:30 AM, Daniel Thompson email@example.com wrote:
On 02/10/15 07:04, Grant Likely wrote:
Try wiring it to the Arduino headers. Make sure the board is /not/ attached to the basebord when programming.
Can you try writing the programmer to the Arduino headers instead of the ISP connection?
Sorry for the delay but it took me a while to dig out an old (and until today, entirely unused) Pro Micro clone. With that I have been able to successfully program the bootloader onto the board.
Photos of the wiring are on flickr for anyone else in a hurry to do this with a Pro Micro (you also need to change "#define RESET SS" to "#define RESET 10" before uploading the sketch):
Having done that I also wanted to check for potential problems on the ISP port:
Hooking up the Pro Micro to the ISP port also allows the board to be programmed OK, so no connectivity problems with the socket.
Hooking up exactly the same pinout to another AVR board also allows that board to be programmed, so no pin out problems with the socket.
USBtinyISP has 1.5k current limiting resistors on the SCK and MOSI lines whilst the sensors board as a 620R+LED circuit attached to SCK. My test board also has 1k+LED circuit attached to SCK and this works OK.
Based on #3 I cracked open by programmer and short circuited R7 (i.e. bypassing the programmer boards current limit on SCK). With this modification I was successfully able to program the sensors board.
Any chance of a transistor switched LED circuit for SCK in v2? ;-) It would be good to be compatible with this fairly popular programmer.
Great work! Thanks for the debugging. Yes, I'll either put in a transistor, or remove the LED entirely.