Can't program Arduino UNO using Mac when circuit is connected

Development Tools IDE 1.x
1

As the title says. Everything works fine when I disconnect the circuit (by unhooking earth), but when if earth of the circuit is connected then I get this kind of stuff

avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

I suspect what's happening is the circuit being connected is somehow unbalancing the bus, and it's likely something to do with shoddy Mac implementation of USB ...

Has anybody seen this issue before? I'd like to be able to reprogram the board without having to disconnect earth each time!

my circuit by the way is just a simple led sequence connected to each of the output pins 0-9

2

Serial upload uses the serial pins: 0 and 1. If you connect hardware to those two pins it will often interfere with serial I/O. Try moving your LEDs to 2-11 instead of 0-9.

3

Yep, that was it! Thanks :slight_smile: