embeddedci 0.2.2

BenchPod pytest client for EmbeddedCI hardware-in-the-loop testing

embeddedci (BenchPod pytest library)

A pytest-friendly Python client for an EmbeddedCI BenchPod — the same device operations you do today with benchpod-cli, available straight from your tests:

• connect to a BenchPod over wifi/network, serial, or the cloud (embeddedci.com)
• power the target on/off
• flash firmware to the target and assert ok / not ok
• emulate an I2C sensor (BMP280) and decode the bus traffic

The same test runs against a pod on your desk or a remote pod in CI: point --benchpod-connection at an IP, a serial port, or embeddedci:<device-name> to drive a named device through embeddedci.com from a GitHub Action (no secrets — it authenticates with the workflow's GitHub OIDC token). See Running in GitHub Actions.

from embeddedci import benchpod

with benchpod.BenchPod("192.168.1.213") as bp:   # or "/dev/ttyACM0", or "serial"
    bp.ping()
    bp.power_on(benchpod.INTERNAL)
    result = bp.flash(
        file="firmware.elf", target="target/stm32f1x.cfg",
        swclk=benchpod.PIN1, swdio=benchpod.PIN2, nreset=benchpod.PIN3,
        target_power=benchpod.INTERNAL,
    )
    assert result.ok
    bp.power_off(benchpod.INTERNAL)

Install

pip install embeddedci
# for the cloud (embeddedci:<device>) destination, add the cloud extra:
pip install "embeddedci[cloud]"

The [cloud] extra pulls in a WebSocket client used only by the embeddedci: destination; local wifi/serial use needs nothing extra.

OpenOCD (required for flashing)

Flashing shells out to OpenOCD, which must be on your PATH. It drives the pod's SWD probe through OpenOCD's remote_bitbang adapter in SWD mode — and SWD support for remote_bitbang only exists in OpenOCD master (post‑0.12.0). The stock packages (apt install openocd, brew install open-ocd) are 0.12.0, whose remote_bitbang is jtag_only; flashing with them fails immediately:

Info : only one transport option; autoselect 'jtag'
Error: Can't change session's transport after the initial selection was made

Install a master snapshot instead — the easiest is xPack OpenOCD:

# macOS / Linux via npm (xpm), or grab a release tarball directly:
npm install -g @xpack-dev-tools/openocd
# or: https://github.com/xpack-dev-tools/openocd-xpack/releases  (extract, add bin/ to PATH)

Verify your OpenOCD can do SWD over remote_bitbang:

openocd -c "adapter driver remote_bitbang" -c "transport list" -c "exit"
# must list:  jtag  swd     (if only 'jtag', it's too old)

Named constants (no magic numbers)

Concept	Constants	Wire value
Target-power eFuse	benchpod.INTERNAL, benchpod.EXTERNAL	1, 2
LA pins (SWCLK/SWDIO/NRESET)	benchpod.PIN1 … benchpod.PIN12	1 … 12

Plain ints still work (efuse=1, swclk=1); they're validated and coerced.

Using it in pytest

Installing the package registers a pytest plugin. Point it at a pod and use the fixtures:

pytest --benchpod-connection=192.168.1.213
# or: export BENCHPOD_CONNECTION=serial

def test_firmware_flashes(benchpod):
    benchpod.power_on(benchpod.INTERNAL)
    assert benchpod.flash(
        file="firmware.elf", target="target/stm32f1x.cfg",
        swclk=benchpod.PIN1, swdio=benchpod.PIN2,
    ).ok

# benchpod_target powers the target on for the test and off at teardown:
def test_with_powered_target(benchpod_target):
    ...

Without a connection configured the fixtures skip rather than fail, so the suite stays green in CI runners without hardware.

Connection strings

Form	Transport
192.168.1.213 or host:8080	wifi/network (JSON over TCP, port 8080 default)
/dev/ttyACM0, COM3	serial (USB CDC-ACM console)
serial / usb	serial, auto-detected by USB VID 0x2E8A
embeddedci:<device-name>	cloud — drive a named device through embeddedci.com (CI only; see below)

Resolution order: explicit argument / --benchpod-connection → benchpod_connection ini option → BENCHPOD_CONNECTION env var.

Running in GitHub Actions (cloud)

The embeddedci:<device-name> destination drives a pod that lives somewhere else — behind NAT, in a lab — through embeddedci.com. Your workflow proves which repo it is with a GitHub OIDC token; the server exchanges that for a short-lived session token scoped to the devices that repo is allowed to drive, then bridges a raw byte tunnel to the device. The full API works — including flashing (SWD) and UART/scope captures — so the same test you run locally runs unchanged in CI.

One-time setup (in the EmbeddedCI web app):

1. Give the device a stable name on the BenchPod page (the editable name; letters/digits/-_., unique per org).
2. On BenchPod → GitHub Actions, add your repo (click Look up to fill the numeric ids) and choose Any device or the specific device(s) this repo may drive.

Then in .github/workflows/hil.yml:

permissions:
  id-token: write          # REQUIRED — lets the job mint a GitHub OIDC token
  contents: read

jobs:
  hil:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with: { python-version: "3.12" }
      - run: pip install "embeddedci[cloud]"
      - run: pytest --benchpod-connection=embeddedci:my-bench-01

No API key or secret is stored — auth is the GitHub OIDC token, exactly like PyPI Trusted Publishing.

Config knobs (only the embeddedci: destination uses these):

Option / env	Default	Purpose
--benchpod-api-base / BENCHPOD_API_BASE	https://embeddedci.com	embeddedci server base URL

If the token can't be minted, the error says exactly why — one of: not running inside a GitHub Action, the job is missing id-token: write permission, or the token request itself failed.

Status of features

Feature	State
Connect (wifi + serial)	✅
Connect (cloud via GitHub OIDC)	✅ server + SDK; device firmware tunnel pending on-hardware bring-up
Power on/off (+ scheduled delay)	✅
Flash + assert ok/not ok	✅ (pure-Python OpenOCD remote_bitbang bridge)
Emulated I2C sensor (BMP280)	✅ wifi + serial (serial via json console mode)
I2C bus decode (benchpod.i2c)	✅ START/STOP, R/W, ACK, register reads
UART capture (capture_uart)	✅ wifi + serial
Signal helpers (capture, gpio_set)	✅ minimal, TCP transport only

Emulated I2C sensor + UART capture (HIL)

The pod can pretend to be an I2C sensor (a BMP280) on two LA channels while you capture the DUT's UART — so you can flash an app, power-cycle it, and assert on its boot output with and without the sensor present:

from embeddedci import benchpod

with benchpod.BenchPod("192.168.1.213") as bp:
    bp.flash(file="app.elf", target="target/stm32f4x.cfg",
             swclk=benchpod.PIN11, swdio=benchpod.PIN12, target_power=benchpod.INTERNAL)

    # I2C is open-drain — enable the pod's pull-ups on SDA/SCL. Pull-ups exist
    # only on LA1-8 (LA1/2=4.7k, LA3/4=2.2k, LA5-8=10k), so put SDA/SCL on LA1/2.
    bp.enable_pullup(benchpod.PIN1, benchpod.PIN2)
    bp.enable_i2c_sensor(benchpod.Sensor.BMP280, sda=benchpod.PIN1, scl=benchpod.PIN2,
                         temperature_c=22.5, pressure_pa=101000)

    # Power-cycle while capturing UART so the boot banner lands in the window.
    cap = bp.power_cycle_and_capture(rx=benchpod.PIN5, tx=benchpod.PIN6,
                                     delay=1.5, duration=6.0, until=r"APP_OK")
    assert cap.match("APP_OK")
    assert cap.match(r"chip id match=0x58|bmp280_detected=yes")

How the power-cycle works: power_cycle_and_capture powers the eFuse off, then schedules a power-on delay seconds out (a pod-side timer via target_power's delay_ms), then enters UART capture — so the scheduled power-on, and the DUT's boot output, land inside the capture window. This sidesteps the firmware's one-connection-at-a-time limit (you can't send a power-on while the UART proxy owns the link).

rx is the LA channel the pod samples (wire the DUT's TX here); tx is the channel the pod drives (DUT's RX).

Serial gets the full JSON API too. The pod's TCP API is JSON; the serial console is normally text-only. The firmware exposes a json console command that switches the console into the same JSON dispatcher (exit with {"cmd":"json_exit"}). The serial transport enters/leaves this mode automatically, so enable_i2c_sensor(...), i2c_sensor_la_decoded(...), etc. work over serial as well as wifi — no code change in your test.

Decode the I2C bus

While the pod serves the emulated sensor it also samples the SDA/SCL lines. The benchpod.i2c module turns that raw capture into decoded transactions, so you can assert what the DUT actually did on the wire — not just that it booted:

from embeddedci import benchpod
from embeddedci.benchpod import i2c

with benchpod.BenchPod("192.168.1.213") as bp:
    bp.enable_i2c_sensor(benchpod.Sensor.BMP280, sda=benchpod.PIN7, scl=benchpod.PIN8)
    bp.power_off(benchpod.INTERNAL); bp.power_on(benchpod.INTERNAL)  # DUT boots & probes

    txns = bp.i2c_sensor_la_decoded(samples=4096, sample_rate_mhz=0.5)
    print(i2c.format_transactions(txns))
    # -> S 0x76W+ 0xD0+ Sr 0x76R+ 0x58- P   (write reg 0xD0, read chip id 0x58)
    assert i2c.read_register(txns, 0x76, 0xD0) == [0x58]

The decoder handles START/repeated-START/STOP, the R/W bit, per-byte ACK/NACK, and the common "write register pointer, then read" pattern (read_register). It works on a (scl, sda) stream too (i2c.decode_samples) and ships a waveform synthesizer (i2c.synthesize) so you can build and decode traces with no hardware — see tests/test_i2c_decode.py.

Getting started: one clean HIL test

The "hello world" of EmbeddedCI HIL — flash → emulate a BMP280 → power-cycle → assert on UART — is in examples/test_bmp280.py, with a wiring table and run command at the top:

pytest examples/test_bmp280.py \
    --benchpod-connection=/dev/tty.usbserial-0001 \   # or an IP for wifi
    --benchpod-firmware=path/to/your_app.elf

It uses the plugin's benchpod, pins and firmware fixtures and the @pytest.mark.hardware marker, and skips automatically without a connection. The pins fixture exposes the pod's 12 generic LA channels (pins.pin_1 … pins.pin_12) plus pins.efuse — there are no role-named pins, since any DUT signal can be on any channel. The example maps its own wiring (which signal is on which channel) in a small wiring fixture at the top. See examples/README.md for the full wiring table.

A more thorough multi-case version (present/absent + I2C-bus decode) lives in tests/examples/test_bmp280_hil.py.

Releasing (maintainers)

Releases publish to PyPI automatically via .github/workflows/publish.yml using PyPI Trusted Publishing (OIDC) — no API token or secret is stored in GitHub.

One-time setup on PyPI (or first via TestPyPI): project → Settings → Publishing → Add a pending publisher with owner embeddedci-com, repo embeddedci-python, workflow publish.yml, environment pypi.

This is a monorepo, so each package releases on its own tag — publish.yml triggers on embeddedci-v* for this package (and embeddedci-mcp-v* for the MCP server). To cut a release:

# 1. bump the version in pyproject.toml (e.g. 0.1.0 -> 0.2.0), commit it
# 2. tag and push — the tag is embeddedci-v<version> and must match the version
git tag embeddedci-v0.2.0
git push origin embeddedci-v0.2.0

The tag push builds the sdist + wheel, runs twine check, and publishes. The git tag is the source of truth for what shipped; keep embeddedci-v<version> equal to the version in pyproject.toml.

Build and verify locally before tagging:

python -m pip install build twine
python -m build           # -> dist/embeddedci-*.tar.gz and *.whl
twine check dist/*