rmt: support invert RMT signal by GPIO matrix

components/driver/include/driver/rmt.h

@@ -29,6 +29,7 @@ extern "C" {
 #include "hal/rmt_types.h"
 
 #define RMT_CHANNEL_FLAGS_AWARE_DFS (1 << 0) /*!< Channel can work during APB clock scaling */
+#define RMT_CHANNEL_FLAGS_INVERT_SIG (1 << 1) /*!< Invert RMT signal */
 
 /** @cond */
 #define RMT_CHANNEL_FLAGS_ALWAYS_ON RMT_CHANNEL_FLAGS_AWARE_DFS  /*!< Deprecated name, defined here for compatibility */
@@ -572,17 +573,18 @@ esp_err_t rmt_set_tx_intr_en(rmt_channel_t channel, bool en);
 esp_err_t rmt_set_tx_thr_intr_en(rmt_channel_t channel, bool en, uint16_t evt_thresh);
 
 /**
-* @brief Set RMT pin
+* @brief Configure the GPIO used by RMT channel
 *
 * @param channel RMT channel
-* @param mode TX or RX mode for RMT
+* @param mode RMT mode, either RMT_MODE_TX or RMT_MODE_RX
-* @param gpio_num GPIO number to transmit or receive the signal.
+* @param gpio_num GPIO number, which is connected with certain RMT signal
+* @param invert_signal Invert RMT signal physically by GPIO matrix
 *
 * @return
-*     - ESP_ERR_INVALID_ARG Parameter error
+*     - ESP_ERR_INVALID_ARG Configure RMT GPIO failed because of wrong parameter
-*     - ESP_OK Success
+*     - ESP_OK Configure RMT GPIO successfully
 */
-esp_err_t rmt_set_pin(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_num);
+esp_err_t rmt_set_gpio(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_num, bool invert_signal);
 
 /**
 * @brief Configure RMT parameters
@@ -903,6 +905,20 @@ __attribute__((deprecated("interrupt should be handled by driver")));
 void rmt_clr_intr_enable_mask(uint32_t mask)
 __attribute__((deprecated("interrupt should be handled by driver")));
 
+/**
+* @brief Set RMT pin
+*
+* @param channel RMT channel
+* @param mode TX or RX mode for RMT
+* @param gpio_num GPIO number to transmit or receive the signal.
+*
+* @return
+*     - ESP_ERR_INVALID_ARG Parameter error
+*     - ESP_OK Success
+*/
+esp_err_t rmt_set_pin(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_num)
+__attribute__((deprecated("use rmt_set_gpio instead")));
+
 #ifdef __cplusplus
 }
 #endif

components/driver/rmt.c

@@ -528,7 +528,7 @@ esp_err_t rmt_set_tx_thr_intr_en(rmt_channel_t channel, bool en, uint16_t evt_th
     return ESP_OK;
 }
 
-esp_err_t rmt_set_pin(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_num)
+esp_err_t rmt_set_gpio(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_num, bool invert_signal)
 {
     RMT_CHECK(channel < RMT_CHANNEL_MAX, RMT_CHANNEL_ERROR_STR, ESP_ERR_INVALID_ARG);
     RMT_CHECK(mode < RMT_MODE_MAX, RMT_MODE_ERROR_STR, ESP_ERR_INVALID_ARG);
@@ -540,15 +540,21 @@ esp_err_t rmt_set_pin(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_nu
     if (mode == RMT_MODE_TX) {
         RMT_CHECK(RMT_IS_TX_CHANNEL(channel), RMT_CHANNEL_ERROR_STR, ESP_ERR_INVALID_ARG);
         gpio_set_direction(gpio_num, GPIO_MODE_OUTPUT);
-        esp_rom_gpio_connect_out_signal(gpio_num, rmt_periph_signals.channels[channel].tx_sig, 0, 0);
+        esp_rom_gpio_connect_out_signal(gpio_num, rmt_periph_signals.channels[channel].tx_sig, invert_signal, 0);
     } else {
         RMT_CHECK(RMT_IS_RX_CHANNEL(channel), RMT_CHANNEL_ERROR_STR, ESP_ERR_INVALID_ARG);
         gpio_set_direction(gpio_num, GPIO_MODE_INPUT);
-        esp_rom_gpio_connect_in_signal(gpio_num, rmt_periph_signals.channels[channel].rx_sig, 0);
+        esp_rom_gpio_connect_in_signal(gpio_num, rmt_periph_signals.channels[channel].rx_sig, invert_signal);
     }
     return ESP_OK;
 }
 
+esp_err_t rmt_set_pin(rmt_channel_t channel, rmt_mode_t mode, gpio_num_t gpio_num)
+{
+    // only for backword compatibility
+    return rmt_set_gpio(channel, mode, gpio_num, false);
+}
+
 static bool rmt_is_channel_number_valid(rmt_channel_t channel, uint8_t mode)
 {
     // RX mode
@@ -688,7 +694,7 @@ esp_err_t rmt_config(const rmt_config_t *rmt_param)
 {
     rmt_module_enable();
 
-    RMT_CHECK(rmt_set_pin(rmt_param->channel, rmt_param->rmt_mode, rmt_param->gpio_num) == ESP_OK,
+    RMT_CHECK(rmt_set_gpio(rmt_param->channel, rmt_param->rmt_mode, rmt_param->gpio_num, rmt_param->flags & RMT_CHANNEL_FLAGS_INVERT_SIG) == ESP_OK,
               "set gpio for RMT driver failed", ESP_ERR_INVALID_ARG);
 
     RMT_CHECK(rmt_internal_config(&RMT, rmt_param) == ESP_OK,

docs/en/api-reference/peripherals/rmt.rst

@@ -119,6 +119,7 @@ Common Parameters
 * Extra miscellaneous parameters for the channel can be set in the **flags**.
 
     * When **RMT_CHANNEL_FLAGS_AWARE_DFS** is set, RMT channel will take REF_TICK or XTAL as source clock. The benefit is, RMT channel can continue work even when APB clock is changing. See :doc:`power_management <../system/power_management>` for more information.
+    * When **RMT_CHANNEL_FLAGS_INVERT_SIG** is set, the driver will invert the RMT signal sending to or receiving from the channel. It just works like an external inverter connected to the GPIO of certain RMT channel.
 
 * A **clock divider**, that will determine the range of pulse length generated by the RMT transmitter or discriminated by the receiver. Selected by setting **clk_div** to a value within [1 .. 255] range. The RMT source clock is typically APB CLK, 80Mhz by default. But when **RMT_CHANNEL_FLAGS_AWARE_DFS** is set in **flags**, RMT source clock is changed to REF_TICK or XTAL.
 
@@ -234,7 +235,7 @@ Previously described function :cpp:func:`rmt_config` provides a convenient way t
 Parameters Common to Transmit and Receive Mode
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-* Selection of a GPIO pin number on the input or output of the RMT - :cpp:func:`rmt_set_pin`
+* Selection of a GPIO pin number on the input or output of the RMT - :cpp:func:`rmt_set_gpio`
 * Number of memory blocks allocated for the incoming or outgoing data - :cpp:func:`rmt_set_mem_pd`
 * Setting of the clock divider - :cpp:func:`rmt_set_clk_div`
 * Selection of the clock source, note that currently one clock source is supported, the APB clock which is 80Mhz - :cpp:func:`rmt_set_source_clk`