fix(rmt): correct TX open-drain handling and idle level#120
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Two related fixes in rmt_new_tx_channel() / rmt_tx_destroy() for the Toit RMT hardware tests on ESP32 and ESP32S3: 1. Open-drain (pad_driver) was enabled for io_od_mode channels but never cleared, and gpio_output_disable() on channel deletion does not clear it. A pin previously used by an open-drain channel therefore stayed open-drain, so a later push-pull channel on the same pin could only drive the line low; with no pull-up this silently broke transmission and a dependent receiver hung forever. The configured drive mode is now established explicitly on create (od_enable/od_disable) and restored to push-pull on destroy. 2. The initial idle level was keyed on io_loop_back -- which Toit sets on every channel -- instead of io_od_mode, so every push-pull output idled high. Transmitting with a done-level of 0 then switched the idle level just before tx_start, which the ESP32 receiver recorded as a spurious leading glitch. Key the high idle level on io_od_mode (the workaround's stated intent); push-pull channels now idle low and no longer glitch. Together these fix the ESP32S3 rmt-test hang and the ESP32 rmt-test leading-glitch failures.
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Two related fixes in rmt_new_tx_channel() / rmt_tx_destroy() for the Toit RMT hardware tests on ESP32 and ESP32S3:
Open-drain (pad_driver) was enabled for io_od_mode channels but never cleared, and gpio_output_disable() on channel deletion does not clear it. A pin previously used by an open-drain channel therefore stayed open-drain, so a later push-pull channel on the same pin could only drive the line low; with no pull-up this silently broke transmission and a dependent receiver hung forever. The configured drive mode is now established explicitly on create (od_enable/od_disable) and restored to push-pull on destroy.
The initial idle level was keyed on io_loop_back -- which Toit sets on every channel -- instead of io_od_mode, so every push-pull output idled high. Transmitting with a done-level of 0 then switched the idle level just before tx_start, which the ESP32 receiver recorded as a spurious leading glitch. Key the high idle level on io_od_mode (the workaround's stated intent); push-pull channels now idle low and no longer glitch.
Together these fix the ESP32S3 rmt-test hang and the ESP32 rmt-test leading-glitch failures.