SolarOS 4.17.7 manual · api

Named runtime buses

A named bus describes a hardware connection: I2C, SPI, UART, MIDI, 1-Wire, or PS/2. Scripts and attached devices refer to its name instead of repeating its wiring. SolarOS tracks which devices use it.

Inspect from the shell

expansion bus list
i2c status i2c0
i2c scan i2c0

Use the names shown on your device. The io app can create and manage buses; Expansion reference lists the wiring arguments.

Inspect before creating

import solaros

for bus in solaros.buses.list():
    print(bus)

Reuse a suitable registered bus instead of creating a duplicate on the same pins. Use attach and detach for leases, and remove only a runtime bus that has no users.

Change the clock of a board-defined or runtime-created named I2C bus without recreating its descriptor:

i2c speed i2c0 400000
i2c status i2c0

The new speed applies to subsequent transfers, including those from attached devices. In io, select the bus and choose Set I2C speed.

Transfer through the registry

Use the API for the bus type: i2c_scan, spi_xfer, uart_read, or onewire_scan. Inspect the result and release any lease even when a transfer fails.

Quick reference

Prefer solaros.buses for named hardware. list and get inspect registered buses; create_i2c, create_onewire, create_ps2, create_spi, create_uart, and create_midi create runtime buses; attach, detach, remove manage lifecycle. Transfer families are i2c_probe or scan or read_reg or write_reg, onewire_reset or scan or xfer, spi_xfer or read or write, and uart_read or write. Inspect descriptors before choosing names, pins, chip selects, or hosts.

A MIDI bus is a first-class, exclusive bus backed internally by an available UART controller. create_midi(name, {"tx": ..., "rx": ...}) does not take a controller number and defaults to 31250 baud. Start job midi to receive and transmit MIDI messages. Use optoisolated MIDI IN and a current-limited MIDI OUT driver; do not wire a DIN MIDI connector directly to ESP32 GPIOs.