pamoja-gpio

I2C address frames with reserved-range checks, the four SPI clock modes, and active-high or active-low pins. One capability of pamoja, one memory-safe Rust core with bindings for TypeScript, Python, and C#.

Install

pip install pamoja-gpio

from pamoja import gpio

This pulls in pamoja-native, the compiled engine. pip install pamoja is the whole framework in one package.

Example

The script the test suite runs, spliced here as it ran.

From bindings/python/guides/gpio.py:

from pamoja.gpio import Edge, Level, Polarity, i2c, pin, spi

# A BME280 answers at the 7-bit address its datasheet gives. That is not the byte that
# goes on the wire: the address shifts up one and the low bit says whether this
# transaction reads or writes, which is the step easiest to get wrong by hand.
BME280 = 0x76
print(f"write to  0x{i2c.address_frame(BME280)[0]:02X}")
print(f"read from 0x{i2c.address_frame(BME280, read=True)[0]:02X}")

# The I2C specification keeps two ranges of addresses for itself, so a part answering in
# either is a wiring mistake rather than a device.
reserved = i2c.RESERVED_FROM
print(f"0x{BME280:02X} reserved: {i2c.is_reserved(BME280)}, "
      f"0x{reserved:02X} reserved: {i2c.is_reserved(reserved)}")

# A 10-bit address spends a reserved prefix over two bytes rather than one, so a bus
# driver has to send a different number of bytes depending on the address it holds.
# This is the worked example UM10204 itself prints.
TEN_BIT_DEVICE = 0x2A5
print(f"a 10-bit address takes {i2c.frame_len(TEN_BIT_DEVICE, ten_bit=True)} bytes")

# Datasheets quote clock polarity and phase as one mode number. Mode 3 idles the clock
# high and samples on the trailing edge.
clock = spi.clock_for(3)
print(f"spi mode 3: idles high {clock.cpol}, samples on the trailing edge {clock.cpha}")

# A relay board sold as active low energises when its pin is driven low. The polarity
# carries that inversion, so no call site has to remember which way round it is.
energise = pin.level_for(Polarity.ACTIVE_LOW, True)
print(f"to energise an active-low relay, drive the pin {energise.name}")

# Releasing it drives the line back high, an edge a falling trigger ignores.
rising = pin.triggers(Edge.RISING, Level.LOW, Level.HIGH)
falling = pin.triggers(Edge.FALLING, Level.LOW, Level.HIGH)
print(f"release seen by a rising trigger: {rising}, by a falling trigger: {falling}")

The same capability in every language

Documentation

• pamoja.gpio reference, every class and function in this module.
• The I2C, SPI, and GPIO guide, with the same example in Rust, TypeScript, and C#.
• Every capability, and the install page.

License

MIT