INA229 FT232H

A small Python driver for the Texas Instruments INA229 SPI power/energy/charge monitor, including an FT232H helper for Adafruit Blinka and pyftdi.

Installation

Install the released package from PyPI:

python -m pip install ina229-ft232h

For local development, clone the repository and install it in editable mode:

python -m pip install -e .

Set BLINKA_FT232H=1 before starting Python whenever the FT232H helper is used.

FT232H wiring

The FT232H uses 3.3 V logic. Keep the SPI harness short and provide a solid ground return. For longer harnesses, reduce the baud rate and consider source series termination on SCK, MOSI, and /CS.

Basic usage

import ina229_ft232h as ina229

spi = ina229.ft232h_spi(baudrate=1_000_000)
device = ina229.INA229(
    spi,
    shunt_ohms=0.01,
    max_current=8.0,
)

print(device.bus_voltage)
print(device.shunt_voltage)
print(device.current)
print(device.power)
print(device.energy)
print(device.charge)
print(device.temperature)

max_current defines the signed CURRENT-register full scale and therefore the current LSB. Choose it above the largest expected transient. The shunt drop must also remain within the selected ADC range:

• adc_range=False: +/-163.84 mV
• adc_range=True: +/-40.96 mV, four times finer resolution

ADC configuration

device.configure_adc(
    mode=ina229.MODE_CONT_ALL,
    vbus_ct=ina229.CT_50US,
    vshunt_ct=ina229.CT_50US,
    temp_ct=ina229.CT_50US,
    avg=ina229.AVG_1,
)

The module exports the INA229 register addresses and MODE_*, CT_*, and AVG_* field constants for lower-level use.

SPI mode note

The INA229 requires falling-edge sampling. Blinka's FT232H backend rejects CPHA=1, while pyftdi's mode-1 three-phase emulation shifted received INA229 words by one bit on the tested hardware. ft232h_spi() therefore defaults the underlying pyftdi port to mode 2, which provides the working edge timing without three-phase emulation. Override it with ft232h_spi(mode=...) if another adapter requires different timing.

Tests

python -m unittest discover -v

Release maintainers can find the trusted-publishing setup and release process in RELEASING.md.