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uRemote for MicroBlocks (MicroRemote)

This library is a stripped-down version of the UARTRemote protocol, adapted for MicroBlocks. It provides a simple, reliable command-based communication protocol over UART.

UARTDevice

This library deploys the Pybricks UARTDevice on the Lego hub side. This is an option that is not standard available in the firmwares of the Pybricks hubs. Therefore, you will find firmwares supporting UARTDevice in the pybricks_firmware directory for EV3, Prime hub and Technic hub. In the README we explain how to flash your hub using the pybricks web installer.

Supported Data Types

The following data types are supported:

  • Number (32 bit integer encoded as UTF-8 text)
  • String (UTF-8)
  • Boolean
  • ByteArray

Protocol Format

Each UART frame has the following structure:

<tot_len> <PREAMBLE> <len_cmd> <cmd> [<data_type> <data_len> <data>]

Field Description

  • total_len
    Total number of bytes in the frame (including the preamble).

  • PREAMBLE
    Fixed synchronization preamble:

<$MU

  • cmd_len
    Length of the command string in bytes.

  • cmd
    Command name encoded as UTF-8.

  • [ ... ]
    Zero or more data fields.

Data Field Format

Each data field consists of:

<type> <data_len> <data>

  • type

    • 'N' — Number
    • 'S' — String
    • 'A' — ByteArray
    • 'B' — Boolean

  • data_len
    Length of the data payload in bytes.

  • data

    • Number: UTF-8 encoded decimal string
    • String: UTF-8 encoded text
    • Boolean: 0x00 = False, 0x01 = True
    • ByteArray: raw bytes

Robust Receive Handling

Incoming UART data is read one byte at a time until a complete frame is received or a timeout occurs.

  • Overall receive timeout: time_out
  • Inter-byte timeout: byte_timeout (fixed at 10 ms)

Preamble Validation

  • The first 4 bytes of the frame must match the preamble <$MU.
  • If the preamble is invalid:
    • The UART receive buffer is cleared (read_all()).
    • The frame is discarded.

This ensures reliable resynchronization even in the presence of noise, dropped bytes, or partial frames.