Using an Arduino Serial USB board with an Ardweeny

This afternoon I joined the world of Arduino hacking. I put together an Ardweeny and hooked it up to an Arduino Serial USB Board. I probably should have used a newer FTDI basic breakout board which supports auto-reset, but I didn’t.

Assembly and Power Up

Putting the Ardweeny together was pretty simple. One word of advice: you do not want to do this without a third hand tool. Even that won’t be enough for soldering the chip onto the headers – you’ll need a friend or some good gentle alligator clips to hold the chip while you do the first tack solders.

I powered it up by connecting +5v of the Ardweeny to +5v of the Serial USB board, and then connecting Gnd on the Ardweeny to Gnd on the Serial USB board. It started blinking right away – always a good sign.

Connecting to USB Serial

Connecting the Ardweeny to the Serial USB board was a little trickier. I used a pair of jumper wires. In one end of each one I stuffed a little clipping of 22 awg bell wire, so I had a female connector at one end and a male connector at the other.

Next, the big (and as far as I can tell undocumented) question: does TX on the Serial USB board go to RX on the Ardweeny and vice versa, or does TX on the Serial USB board go straight to TX on the Ardweeny? The answer:

TX on the Serial USB board (the pin furthest from Gnd on the left side) goes to RXI (the pin above A4 on the Ardweeny v1.1a)

RX on the Serial USB board (the pin just above +5v on the left side) goes to TXO (the pin above A3 on the Ardweeny v1.1a)

I hooked those up backwards and my USB port stopped recognizing the Serial USB board. I had to pull the Serial USB board from the USB hub and plug it back in to continue. (I’m doing all of this through a powered USB hub just to avoid burning out my motherboard’s USB if I make a mistake.)

Downloading Code

Once I’d done that, I sent a program down. The first program went with no problems after I set my COM port and chose the “Arudino Duemilanove or Nano w/ATmega 328”.

Subsequent programs wouldn’t write – I got the following error:

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

It turns out the Ardweeny is pretty particular about when things get uploaded to it. (This is where the auto-reset function of the FTDI basic breakout board shines, but I didn’t know that since I’d never done Arduino programming before.) So the magic trick to upload is to wait until you see:

Binary sketch size: 1018 bytes (of a 30720 byte maximum)

in the IDE, then immediately hit the reset button on the Ardweeny. At that point, you’ll see the TX and RX LEDs flash on the USB Serial board, and your code should be uploaded.

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