Confessions of a prototyper: Bus Pirate v1.5


The Bus Pirate V2a and V2go weren’t the only design candidates for the Bus Pirate v2 series. Here’s a rendering of the Bus Pirate ‘v1.5’, a design that never saw the light of day. This Bus Pirate was meant to be completely portable. It has an LCD to display the terminal, and a keyboard jack to work with a roll-up rubber keyboard.

Here’s some of the differences between this version and the final v2 series.

  1. This design didn’t include software controlled pull-up resistors. It uses the jumper concept from v1a with SMD resistors.
  2. V1.5 included a Nokia LCD knock off, like the one SparkFun sells for $15. The LCD backlight needs 7volts, so the large SOT223 regulator behind the power supply is a LM317 set to 7volts. The LM317 also supplies the other regulators with 7volts, which is better than the 5V supply to 5volt regulators on the v2a and v2go.
  3. The six hole pattern seen on both sides of the PCB is for the PC keyboard connector. PC keyboards operate at 5volts, so this feature took two of only seven 5volt tolerant pins on the PIC24FJ64.

When we decided to manufacture the Bus Pirate, this design was too complicated and expensive. The code to run the LCD terminal and read the keyboard was big and made it hard to add new protocols. The knock-off Nokia LCDs are really inconsistent too, even different batches from SparkFun require different drivers. We minimized the design first to the v2a, then to the v2go.

In the end, we’re really pleased with the v2go. In retrospect, however, there were a few changes that would have make the whole process smoother. These have been integrated into the updated Bus Pirate v3, which is an even cleaner design that should be easier to manufacture in quantity.

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