[TW#15165] RMT isn't working correctly on master

[MartyMacGyver]

The RMT device is no longer transmitting as expected in transmit mode.

This isn't working for my code:
https://github.com/MartyMacGyver/ESP32-Digital-RGB-LED-Drivers

Nor is it working against the code my code was originally based upon:
https://github.com/FozzTexx/ws2812-demo

As was reported to me via MartyMacGyver/ESP32-Digital-RGB-LED-Drivers#9, undoing commit 17747b3 rectifies the problem. It's not yet clear whether there is a bug in that commit or if there is extra code required to work successfully based upon it.

For reference, there was some discussion here but it was inconclusive:
https://www.esp32.com/viewtopic.php?f=13&t=2339&p=11273

[MartyMacGyver]

This may be resolved now - at least, it seems to be working for me.

Both our demos used the old GPIO constuction:

....
DPORT_SET_PERI_REG_MASK(DPORT_PERIP_CLK_EN_REG, DPORT_RMT_CLK_EN);
DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG, DPORT_RMT_RST);
PIN_FUNC_SELECT(GPIO_PIN_MUX_REG[gpioNum], 2);
gpio_matrix_out((gpio_num_t)gpioNum, RMT_SIG_OUT0_IDX + RMTCHANNEL, 0, 0);
gpio_set_direction((gpio_num_t)gpioNum, GPIO_MODE_OUTPUT);
...RMT initialization code follows...

Using the rmt_set_pin() (from driver/rmt.h) instead seems to resolve the issue:

....
DPORT_SET_PERI_REG_MASK(DPORT_PERIP_CLK_EN_REG, DPORT_RMT_CLK_EN);
DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG, DPORT_RMT_RST);
rmt_set_pin(static_cast<rmt_channel_t>(RMTCHANNEL),
            RMT_MODE_TX,
            static_cast<gpio_num_t>(gpioNum));
...RMT initialization code follows...

Edit: one needs to include drivers/rmt.h to use this. If you're using C, use C-style casts instead of static_cast<type> e.g. (rmt_channel_t)RMTCHANNEL.

[igrr]

Previously, gpio_set_direction did not make sure that GPIO function was actually selected in the GPIO matrix. Now it switches to GPIO signal, which undoes the effect of gpio_matrix_out(..., RMT_SIG_OUT0_IDX + RMTCHANNEL, 0, 0);. Either switch the order of the two statements, or use rmt_set_pin as a higher-level solution, as you did.

[MartyMacGyver]

Thanks for the extra info!