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pio_encode_gpio_wait doc improvement #2579

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Merged
merged 3 commits into from
Jul 25, 2025
Merged

pio_encode_gpio_wait doc improvement #2579

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c416d02
better document the GPIO_BASE requirements of pio_encode_gpio_wait, a…
kilograham Jul 21, 2025
f84f2e1
add proviso
kilograham Jul 21, 2025
b2c3287
Apply suggestions from code review
kilograham Jul 25, 2025
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10 changes: 5 additions & 5 deletions src/rp2_common/hardware_pio/include/hardware/pio_instructions.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,10 +18,6 @@
* parameters.
*
* For fuller descriptions of the instructions in question see the "RP2040 Datasheet"
*
* NOTE: These are helper functions for the raw instruction encoding, and thus
* only provide support for pins numbered 0-31. You should adjust your encoding
* according to your expected GPIO_BASE (see \ref pio_set_gpio_base)
*/

// PICO_CONFIG: PARAM_ASSERTIONS_ENABLED_PIO_INSTRUCTIONS, Enable/disable assertions in the PIO instructions, type=bool, default=0, group=pio_instructions
Expand Down Expand Up @@ -271,8 +267,12 @@ static inline uint _pio_encode_irq(bool relative, uint irq) {
*
* This is the equivalent of `WAIT <polarity> GPIO <gpio>`
*
* \note gpio here refers to the raw instruction encoding, which only supports 32 GPIOs. So, if you had a PIO
* program with `WAIT <polarity> GPIO 42` and a GPIO_BASE (see \ref pio_set_gpio_base) of 16, then you'd want to do
* `pio_encode_wait_gpio(polarity, 42-16)` assuming you are using this function to craft instructions for \ref pio_sm_exec.
*
* \param polarity true for `WAIT 1`, false for `WAIT 0`
* \param gpio The real GPIO number 0-31
* \param gpio The GPIO number 0-31 relative to the state machine's GPIO_BASE (see \ref pio_set_gpio_base)
* \return The instruction encoding with 0 delay and no side set value
* \see pio_encode_delay, pio_encode_sideset, pio_encode_sideset_opt
*/
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