Remove physical CS loopback requirement

Hope this does not break the ESP32 because of the
SPI_LL_SLAVE_NEEDS_CS_WORKAROUND in the IDF code.

Author: hberntsen

Hardware.md

@@ -46,4 +46,4 @@ It was not tested to directly plug the MHI-AC-Ctrl-ESP32-C3 into the AC unit. In
 The JST connector provides +12V. The DC-DC converter [TSR 1-2450](https://www.tracopower.com/products/browse-by-category/find/tsr-1/3/) converts the +12V to +5V.
 
 ## Signal Connection
-The ESP32-C3 SPI signals SCL (SPI clock), MOSI (Master Out Slave In) and MISO (Master In Slave Out) are connected via a voltage level shifter 5V <-> 3.3V with the AC. Direct connection of the signals without a level shifter could damage your ESP32-C3! Note that the CNS connector does not provide a Chip Select signal, this is generated internally on the ESP32-C3 and routed back through IO9 and IO10.
+The ESP32-C3 SPI signals SCL (SPI clock), MOSI (Master Out Slave In) and MISO (Master In Slave Out) are connected via a voltage level shifter 5V <-> 3.3V with the AC. Direct connection of the signals without a level shifter could damage your ESP32-C3! Note that the CNS connector does not provide a Chip Select signal, this is generated internally on the ESP32-C3. We used to physically route an internally generated signal from IO9 and IO10. The physical pins are currently not needed any more.

README.md

@@ -15,7 +15,6 @@ This code is inspired by [@absalom-muc's MHI-AC-Ctrl](https://github.com/absalom
 ### Community supported:
 * [ESP32-C6](https://github.com/hberntsen/mhi-ac-ctrl-esp32-c3/pull/25)
 * Other ESP32-C3 boards (e.g. [ESP32-C3 super mini](https://github.com/xangin/mhi-ac-ctrl-esp32-c3/blob/master/Hardware.md)).
-  Note that the hardware SPI used in this project needs a GPIO loopback for the chip select. Connect two free GPIOs for that, like IO9 and IO10 in the [schematic](images/MHI-AC-Ctrl_Schematic.png).
 * The ESP32 [has been reported to work](https://github.com/hberntsen/mhi-ac-ctrl-esp32-c3/issues/12#issuecomment-2594627493). Make sure you use the right pins, as discussed in [#11](https://github.com/hberntsen/mhi-ac-ctrl-esp32-c3/issues/11).
 * The AC units listed at https://github.com/absalom-muc/MHI-AC-Ctrl?tab=readme-ov-file#prerequisites should work. Some older units have to use the `use_long_frame: false` setting.
 

esphome/components/MhiAcCtrl/MHI-AC-Ctrl-core.cpp

@@ -12,6 +12,7 @@
 #include "driver/gptimer.h"
 #include "driver/spi_slave.h"
 #include "driver/gpio.h"
+#include "soc/spi_periph.h"
 
 //#undef LOG_LOCAL_LEVEL
 //#define LOG_LOCAL_LEVEL ESP_LOG_VERBOSE
@@ -35,7 +36,6 @@ static StackType_t xStack[ STACK_SIZE ];
 static TaskHandle_t mhi_poll_task_handle = NULL;
 
 static bool active_mode = false;
-static gpio_num_t gpio_cs_out;
 
 namespace mhi_ac {
 
@@ -78,8 +78,8 @@ static bool IRAM_ATTR gptimer_isr_callback(gptimer_handle_t timer, const gptimer
     gptimer_set_raw_count(cs_timer, 0);
 
     // Trigger Chip Select low->high->low
-    gpio_set_level(gpio_cs_out, 1);
-    gpio_set_level(gpio_cs_out, 0);
+    esp_rom_gpio_connect_in_signal(GPIO_MATRIX_CONST_ONE_INPUT, spi_periph_signal[RCV_HOST].spics_in, false);
+    esp_rom_gpio_connect_in_signal(GPIO_MATRIX_CONST_ZERO_INPUT, spi_periph_signal[RCV_HOST].spics_in, false);
 
     vTaskNotifyGiveFromISR(mhi_poll_task_handle, &xHigherPriorityTaskWoken);
 
@@ -567,25 +567,9 @@ static void mhi_poll_task(void *arg)
     }
 }
 
-/**
- * Checks whether the GPIO CS loopback works by toggling it a few times.
- */
-static bool check_gpio_cs_loopback(gpio_num_t cs_in_pin) {
-  int on = 0;
-  for(int i = 0; i < 42; i++) {
-    gpio_set_level(gpio_cs_out, on);
-    if(gpio_get_level(cs_in_pin) != on) {
-      return false;
-    }
-    on ^= 1;
-  }
-  return true;
-}
-
-InitError init(const Config& config) {
+void init(const Config& config) {
     esp_err_t err;
 
-    gpio_cs_out = static_cast<gpio_num_t>(config.cs_out_pin);
     spi_state.use_long_frame(config.use_long_frame);
 
     // configuration for the SPI bus
@@ -606,7 +590,7 @@ InitError init(const Config& config) {
 
     // configuration for the SPI slave interface
     spi_slave_interface_config_t slvcfg = {
-        .spics_io_num = config.cs_in_pin,
+        .spics_io_num = -1,
         .flags = SPI_SLAVE_BIT_LSBFIRST,
         .queue_size = 1,
         .mode = 3,                    //CPOL=1, CPHA=1
@@ -618,6 +602,8 @@ InitError init(const Config& config) {
     err = spi_slave_initialize(RCV_HOST, &buscfg, &slvcfg, SPI_DMA_CH_AUTO);    // can't disable DMA. no comms if you do...
     ESP_ERROR_CHECK(err);
 
+    esp_rom_gpio_connect_in_signal(GPIO_MATRIX_CONST_ONE_INPUT, spi_periph_signal[RCV_HOST].spics_in, false);
+
     // Set up timer
     gptimer_config_t timer_config = {
       .clk_src = GPTIMER_CLK_SRC_DEFAULT,
@@ -660,20 +646,6 @@ io_conf.pull_down_en = GPIO_PULLDOWN_DISABLE;
     gpio_isr_handler_add(static_cast<gpio_num_t>(config.sclk_pin), gpio_isr_handler, NULL);
     gpio_intr_enable(static_cast<gpio_num_t>(config.sclk_pin));
 
-    io_conf.mode = GPIO_MODE_OUTPUT;
-    io_conf.pin_bit_mask = (1ULL<<gpio_cs_out);
-    io_conf.intr_type =GPIO_INTR_DISABLE;
-    io_conf.pull_up_en = GPIO_PULLUP_DISABLE;
-    gpio_config(&io_conf);
-
-    if(!check_gpio_cs_loopback(static_cast<gpio_num_t>(config.cs_in_pin))) {
-      return InitError::CSLoopbackFail;
-    }
-
-    gpio_set_level(gpio_cs_out, 1);
-
     mhi_poll_task_handle = xTaskCreateStatic(mhi_poll_task, "mhi_task", STACK_SIZE, NULL, 10, xStack, &xTaskBuffer);
-
-    return InitError::Ok;
 }
 } //namespace mhi_ac

esphome/components/MhiAcCtrl/MHI-AC-Ctrl-core.h

@@ -37,8 +37,6 @@ struct Config {
   uint8_t mosi_pin;
   uint8_t miso_pin;
   uint8_t sclk_pin;
-  uint8_t cs_in_pin;
-  uint8_t cs_out_pin;
 };
 
 enum class ACPower {
@@ -72,13 +70,7 @@ enum class ACVanesLR {
   Left = 0, LeftCenter = 1, Center = 2, CenterRight = 3, Right = 4, Wide = 5, Spot = 6, Swing = 8
 };
 
-enum class InitError {
-  Ok = 0,
-  CSLoopbackFail
-};
-
-
-InitError init(const Config& config);
+void init(const Config& config);
 
 void active_mode_set(bool state);
 bool active_mode_get();

esphome/components/MhiAcCtrl/__init__.py

@@ -18,17 +18,13 @@
 CONF_MOSI_PIN = "mosi_pin"
 CONF_MISO_PIN = "miso_pin"
 CONF_SCLK_PIN = "sclk_pin"
-CONF_CS_IN_PIN = "cs_in_pin"
-CONF_CS_OUT_PIN = "cs_out_pin"
 
 TYPES = [
     CONF_EXTERNAL_TEMPERATURE_SENSOR,
     CONF_USE_LONG_FRAME,
     CONF_MOSI_PIN,
     CONF_MISO_PIN,
     CONF_SCLK_PIN,
-    CONF_CS_IN_PIN,
-    CONF_CS_OUT_PIN,
 ]
 
 CONFIG_SCHEMA = cv.Schema(
@@ -39,8 +35,6 @@
         cv.Optional(CONF_MOSI_PIN, default="GPIO7"): pins.gpio_input_pin_schema,
         cv.Optional(CONF_MISO_PIN, default="GPIO2"): pins.gpio_output_pin_schema,
         cv.Optional(CONF_SCLK_PIN, default="GPIO6"): pins.gpio_input_pin_schema,
-        cv.Optional(CONF_CS_IN_PIN, default="GPIO10"): pins.gpio_input_pin_schema,
-        cv.Optional(CONF_CS_OUT_PIN, default="GPIO9"): pins.gpio_output_pin_schema,
     }
 ).extend(cv.COMPONENT_SCHEMA)
 
@@ -51,8 +45,6 @@ async def to_code(config):
         ("mosi_pin", (await cg.gpio_pin_expression(config[CONF_MOSI_PIN])).get_pin()),
         ("miso_pin", (await cg.gpio_pin_expression(config[CONF_MISO_PIN])).get_pin()),
         ("sclk_pin", (await cg.gpio_pin_expression(config[CONF_SCLK_PIN])).get_pin()),
-        ("cs_in_pin", (await cg.gpio_pin_expression(config[CONF_CS_IN_PIN])).get_pin()),
-        ("cs_out_pin", (await cg.gpio_pin_expression(config[CONF_CS_OUT_PIN])).get_pin()),
     )
 
     var = cg.new_Pvariable(config[CONF_ID], config_struct)

esphome/components/MhiAcCtrl/mhi_ac_ctrl.h

@@ -246,12 +246,7 @@ class MhiAcCtrl : public climate::Climate,
         if(this->operation_data_visible_timeouts_sensor_) {
           this->operation_data_visible_timeouts_sensor_->publish_state(0);
         }
-        mhi_ac::InitError err = mhi_ac::init(this->ac_config_);
-        switch(err) {
-          case mhi_ac::InitError::CSLoopbackFail:
-            this->status_set_error(LOG_STR("CS loopback check failed. Are cs_in_pin and cs_out_pin connected with each other?"));
-            return;
-        }
+        mhi_ac::init(this->ac_config_);
 
         constexpr auto opdatas = &mhi_ac::operation_data_state;
         opdatas->set_temperature_.enabled = this->set_temperature_sensor_;

esphome/example.yaml

@@ -36,8 +36,6 @@ MhiAcCtrl:
   mosi_pin: GPIO7
   miso_pin: GPIO2
   sclk_pin: GPIO6
-  cs_in_pin: GPIO10
-  cs_out_pin: GPIO9
 
 climate:
   - platform: MhiAcCtrl