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The documentation on the state `GPIO_DISCONNECT` was a bit vague. The API doc said it should disconnect the GPIO from all peripherals, the test also tested them for being electrically disconnected. The documentation in both the test and the API is extended to point out that a GPIO indeed SHOULD be in high impedance state, but that user MUST NOT expect that this requested is honored by every implementation and for every GPIO pin. In the test it is also pointed out that failing the test for a GPIO in the `GPIO_DISCONNECT` state being electrically disconnected is for some pins expected, and that the test should be just run again with different GPIOs. The test intentionally tests for a feature not provided by every GPIO pin rather than warning on a failure: The effort to just flash and run the test again with different GPIOs is relatively low, but it does confirm correct behavior of the API.
30 lines
1.5 KiB
Markdown
30 lines
1.5 KiB
Markdown
# Test for `periph/gpio_ll`
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This application will use two output and two input GPIOs, which have to be
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connected via a jumper wire. The test will change the value of the two pins
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output pins and use the input pins to read the value back in. If the value read
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doesn't match the expected result, the test aborts and fails.
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If IRQ support is provided, the test will additionally walk through every IRQ
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configuration for the first GPIO pin given and iterate over any trigger
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condition possible. It will check that edge trigger and (if supported) level
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trigger IRQs trigger exactly on the configured triggers.
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## Configuration
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Configure in the `Makefile` or set via environment variables the number of
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the output GPIO port to use via the `PORT_OUT` variable. The `PIN_OUT_0` and
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`PIN_OUT_1` variables select the pins to use within that GPIO port. The input
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GPIO port is set via `PORT_IN`. Both `PORT_IN == PORT_OUT` and
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`PORT_IN != PORT_OUT` is valid. The input pin number within `PORT_IN` are set
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via `PIN_IN_0` and `PIN_IN_1`. `PIN_IN_0` has to be wired to `PIN_OUT_0`, and
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`PIN_IN_1` to `PIN_OUT_1`.
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## Expected Failures
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Implementations are allowed to not electrically disconnect GPIO pins in state
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`GPIO_DISCONNECT`. The test will however test for pins to be electrically
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disconnected. For every MCU supported by GPIO LL so far at least some pins can
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be electrically disconnected. You might need to change the GPIO pins tested
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if the test for disconnected GPIOs being also electrically disconnected.
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