Seeedstudio Bus Pirate v4 1kHz-4MHz pulse-width modulator, frequency generator. On-board multi-voltage pull-up resistors On-board 3.3volt and 5volt power supplies with software reset. Macros for common operations Bus traffic sniffers (SPI, I2C). Transparent USB-&gt;serial bridge mode 10Hz-1MHz low-speed logic analyzer. AVR STK500 v2 programmer clone Scriptable from Perl, Python, etc. A bootloader for easy USB firmware updates