Implement variable length single word SPI writes. (#5678)

esphome/components/spi/spi.cpp

@@ -77,15 +77,19 @@ void SPIComponent::dump_config() {
 
 void SPIDelegateDummy::begin_transaction() { ESP_LOGE(TAG, "SPIDevice not initialised - did you call spi_setup()?"); }
 
-uint8_t SPIDelegateBitBash::transfer(uint8_t data) {
+uint8_t SPIDelegateBitBash::transfer(uint8_t data) { return this->transfer_(data, 8); }
+
+void SPIDelegateBitBash::write(uint16_t data, size_t num_bits) { this->transfer_(data, num_bits); }
+
+uint16_t SPIDelegateBitBash::transfer_(uint16_t data, size_t num_bits) {
   // Clock starts out at idle level
   this->clk_pin_->digital_write(clock_polarity_);
   uint8_t out_data = 0;
 
-  for (uint8_t i = 0; i < 8; i++) {
+  for (uint8_t i = 0; i != num_bits; i++) {
     uint8_t shift;
     if (bit_order_ == BIT_ORDER_MSB_FIRST) {
-      shift = 7 - i;
+      shift = num_bits - 1 - i;
     } else {
       shift = i;
     }
@@ -94,7 +98,7 @@ uint8_t SPIDelegateBitBash::transfer(uint8_t data) {
       // sampling on leading edge
       this->sdo_pin_->digital_write(data & (1 << shift));
       this->cycle_clock_();
-      out_data |= uint8_t(this->sdi_pin_->digital_read()) << shift;
+      out_data |= uint16_t(this->sdi_pin_->digital_read()) << shift;
       this->clk_pin_->digital_write(!this->clock_polarity_);
       this->cycle_clock_();
       this->clk_pin_->digital_write(this->clock_polarity_);
@@ -104,7 +108,7 @@ uint8_t SPIDelegateBitBash::transfer(uint8_t data) {
       this->clk_pin_->digital_write(!this->clock_polarity_);
       this->sdo_pin_->digital_write(data & (1 << shift));
       this->cycle_clock_();
-      out_data |= uint8_t(this->sdi_pin_->digital_read()) << shift;
+      out_data |= uint16_t(this->sdi_pin_->digital_read()) << shift;
       this->clk_pin_->digital_write(this->clock_polarity_);
     }
   }

esphome/components/spi/spi.h

@@ -199,6 +199,15 @@ class SPIDelegate {
       rxbuf[i] = this->transfer(txbuf[i]);
   }
 
+  /**
+   * write a variable length data item, up to 16 bits.
+   * @param data The data to send. Should be LSB-aligned (i.e. top bits will be discarded.)
+   * @param num_bits The number of bits to send
+   */
+  virtual void write(uint16_t data, size_t num_bits) {
+    esph_log_e("spi_device", "variable length write not implemented");
+  }
+
   // write 16 bits
   virtual void write16(uint16_t data) {
     if (this->bit_order_ == BIT_ORDER_MSB_FIRST) {
@@ -270,6 +279,10 @@ class SPIDelegateBitBash : public SPIDelegate {
 
   uint8_t transfer(uint8_t data) override;
 
+  void write(uint16_t data, size_t num_bits) override;
+
+  void write16(uint16_t data) override { this->write(data, 16); };
+
  protected:
   GPIOPin *clk_pin_;
   GPIOPin *sdo_pin_;
@@ -284,6 +297,7 @@ class SPIDelegateBitBash : public SPIDelegate {
       continue;
     this->last_transition_ += this->wait_cycle_;
   }
+  uint16_t transfer_(uint16_t data, size_t num_bits);
 };
 
 class SPIBus {
@@ -408,6 +422,8 @@ class SPIDevice : public SPIClient {
 
   void read_array(uint8_t *data, size_t length) { return this->delegate_->read_array(data, length); }
 
+  void write(uint16_t data, size_t num_bits) { this->delegate_->write(data, num_bits); };
+
   void write_byte(uint8_t data) { this->delegate_->write_array(&data, 1); }
 
   void transfer_array(uint8_t *data, size_t length) { this->delegate_->transfer(data, length); }

esphome/components/spi/spi_esp_idf.cpp

@@ -72,7 +72,11 @@ class SPIDelegateHw : public SPIDelegate {
       desc.rxlength = this->write_only_ ? 0 : partial * 8;
       desc.tx_buffer = txbuf;
       desc.rx_buffer = rxbuf;
-      esp_err_t const err = spi_device_transmit(this->handle_, &desc);
+      // polling is used as it has about 10% less overhead than queuing an interrupt transfer
+      esp_err_t err = spi_device_polling_start(this->handle_, &desc, portMAX_DELAY);
+      if (err == ESP_OK) {
+        err = spi_device_polling_end(this->handle_, portMAX_DELAY);
+      }
       if (err != ESP_OK) {
         ESP_LOGE(TAG, "Transmit failed - err %X", err);
         break;
@@ -85,6 +89,21 @@ class SPIDelegateHw : public SPIDelegate {
     }
   }
 
+  void write(uint16_t data, size_t num_bits) override {
+    spi_transaction_ext_t desc = {};
+    desc.command_bits = num_bits;
+    desc.base.flags = SPI_TRANS_VARIABLE_CMD;
+    desc.base.cmd = data;
+    esp_err_t err = spi_device_polling_start(this->handle_, (spi_transaction_t *) &desc, portMAX_DELAY);
+    if (err == ESP_OK) {
+      err = spi_device_polling_end(this->handle_, portMAX_DELAY);
+    }
+
+    if (err != ESP_OK) {
+      ESP_LOGE(TAG, "Transmit failed - err %X", err);
+    }
+  }
+
   void transfer(uint8_t *ptr, size_t length) override { this->transfer(ptr, ptr, length); }
 
   uint8_t transfer(uint8_t data) override {
@@ -93,14 +112,7 @@ class SPIDelegateHw : public SPIDelegate {
     return rxbuf;
   }
 
-  void write16(uint16_t data) override {
+  void write16(uint16_t data) override { this->write(data, 16); }
-    if (this->bit_order_ == BIT_ORDER_MSB_FIRST) {
-      uint16_t txbuf = SPI_SWAP_DATA_TX(data, 16);
-      this->transfer((uint8_t *) &txbuf, nullptr, 2);
-    } else {
-      this->transfer((uint8_t *) &data, nullptr, 2);
-    }
-  }
 
   void write_array(const uint8_t *ptr, size_t length) override { this->transfer(ptr, nullptr, length); }