UART Protocol Commands
Overview
- Bus: UART, MIDI (universal asynchronous receiver transmitter)
- Connections: two pins (RX/TX) and ground
- Output type: 1.65-5volts. Powered by onboard supply or an external voltage on the VOUT/VREF pin
- Maximum Voltage: 5volts
UART is also known as the common PC serial port. The PC serial port operates at full RS232 voltage levels (-13volts to +13volts) though, which are not compatible with the Bus Pirate.
Configuration options
1200, 2400, 4800, 19200, 38400, 57600, 115200 etc
x. Exit
Baud (115200*) >
Data bits
5 to 8 bits
x. Exit
Bits (8*) >
Parity
1. None*
2. Even
3. Odd
x. Exit
Parity (1) >
Stop bits
1. 1*
2. 2
x. Exit
Bits (1) >
Actual speed: 115207 baud
Mode: UART
UART>
Syntax
| Command | Description |
|---|---|
| [ | Open UART, use r to read bytes. |
| { | Open UART, display data as it arrives asynchronously. |
| ] or } | Close UART. |
| r | Check UART for byte, or fail if empty. (r:1…255 for bulk reads) |
| 0b | Write this binary value. Format is 0b00000000 for a byte, but partial bytes are also fine: 0b1001. |
| 0x | Write this HEX value. Format is 0x01. Partial bytes are fine: 0xA. A-F can be lower-case or capital letters. |
| 0-255 | Write this decimal value. Any number not preceded by 0x or 0b is interpreted as a decimal value. |
space | Value delimiter. Use a space to separate numbers. No delimiter is required between non-number values: {0xa6 0 0 16 5 0b111 0xaF rrrr}. |
| (#) | Run macro, (0) for macro list. |
Macros
Macro list
| Number | Description |
|---|---|
| 0 | Macro menu |
| 1 | Transparent UART bridge. Press the Bus Pirate button to exit. |
| 2 | GPS NMEA sentence decoder. Press any key to exit. |
Transparent UART bridge
UART mode macro (1) opens a simple serial->USB bridge.
To exit, press the button on the Bus Pirate.
GPS NMEA sentence decoder
Most GPS modules output NMEA sentences through a serial UART. Macro (2) decodes common sentences using minmea. The raw data and decoded data are printed in the terminal. Press any key to exit.
MIDI
MIDI is a command set used by electronic (music) instruments. It travels over a standard serial UART configured for 31250bps/8/n/1.
MIDI is a ring network, each node has an input and output socket. Each node passes messages to the next in the ring. The input and outputs are opto-isolated. The signaling is at 5volts, 5ma (current-based signaling). An adapter is required: example 1, example 2.
Connections
| Bus Pirate | Direction | Circuit | Description |
|---|---|---|---|
| TX | → | RX | Bus Pirate Transmit |
| RX | ← | TX | Bus Pirate Receive |
| GND | ⏚ | GND | Signal Ground |
Connect the Bus Pirate transmit pin (TX) to the UART device receive pin (RX). Connect the Bus Pirate receive pin (RX) to the UART device transmit pin (TX).