main: configure SPI for LCD frame recording

main/main.c

@@ -21,6 +21,20 @@
 // GPIO for on-board LED (WEMOS S2 mini, source on)
 #define LED_BOARD 15
 
+/* GM1352 test pads:
+ * - CS: LCD chip select, to start data communication
+ * - DATA: LCD data bits
+ * - WR: LCD data clock (not periodic)
+ * - S: ??? (low)
+ * - 1: HOLD button (press low)
+ * - 2: MIN/MAX button (press low)
+ * - 3: POWER button (press low)
+ */
+#define GPIO_POWER (35U)
+#define GPIO_MOSI (16U)
+#define GPIO_SCLK (33U)
+#define GPIO_CS (18U)
+
 static const char *TAG = "main";
 
 /**
@@ -85,10 +99,34 @@ void app_main(void)
 	tinyusb_config_cdcacm_t amc_cfg = { 0 }; // the configuration uses default values
 	ESP_ERROR_CHECK( tusb_cdc_acm_init(&amc_cfg) ); // configure CDC ACM
 	ESP_ERROR_CHECK( tusb_dfu_rf_init() ); // configure DFU runtime (ensures we can use it)
-	esp_tusb_init_console(TINYUSB_CDC_ACM_0); // log to USB
 	ESP_LOGI(TAG, "USB initialized");
 
+	// configure SPI for GM1352 LCD data frame reading
+	const spi_bus_config_t buscfg = { // SPI bus configuration
+		.mosi_io_num = GPIO_MOSI,
+		.miso_io_num = -1,
+		.sclk_io_num = GPIO_SCLK,
+		.quadwp_io_num = -1,
+		.quadhd_io_num = -1,
+	};
+	spi_slave_interface_config_t slvcfg={
+		.mode = 0,
+		.spics_io_num = GPIO_CS,
+		.queue_size = 3,
+		.flags = 0,
+		.post_setup_cb = NULL,
+		.post_trans_cb = post_trans_cb,
+	};
+	ESP_ERROR_CHECK( spi_slave_initialize(SPI2_HOST, &buscfg, &slvcfg, SPI_DMA_CH_AUTO) );
+	spi_slave_transaction_t t; // for the SPI transaction
+	memset(&t, 0, sizeof(t)); // clear transaction
+	t.length = FRAME_SIZE * 8; // transaction size
+	WORD_ALIGNED_ATTR uint8_t recvbuf[FRAME_SIZE]; // SPI receive buffer must be word aligned for DMA
+	t.rx_buffer = recvbuf; // set buffer
+	spi_slave_queue_trans(SPI2_HOST, &t, portMAX_DELAY);
+
 	ESP_LOGI(TAG, "application ready");
+	esp_tusb_init_console(TINYUSB_CDC_ACM_0); // log to USB
 	gpio_set_level(LED_BOARD, 0); // switch running LED on to indicate all is ready
 	while (1) {
 		vTaskDelay(1000 / portTICK_PERIOD_MS);