diff --git a/main/main.c b/main/main.c
index 9846e35..301af6c 100644
--- a/main/main.c
+++ b/main/main.c
@@ -6,8 +6,11 @@
 #include <sys/reent.h>
 #include "esp_log.h"
 #include "esp_mac.h"
+
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
+#include "freertos/queue.h"
+
 #include "tinyusb.h"
 #include "tusb_cdc_acm.h"
 #include "tusb_dfu_rt.h"
@@ -41,6 +44,134 @@
 
 static const char *TAG = "main";
 
+/* the MCU sends 1 or 17 bytes frame the to LCD controller
+ * the below described which bit corresponds to which segment
+ * digit 1 is left most on the LCD, bit 7 is the most significant bit.
+ *
+ * byte 0:
+ * - 0x80: initialize LCD controller (1 byte frame)
+ * - 0xa0: set segments (17 bytes frame)
+ *
+ * byte 1:
+ * - bit 7: no segment
+ * - bit 6: no segment
+ * - bit 5: battery low level
+ * - bit 4: battery mid level
+ * - bit 3: battery high level
+ * - bit 2: OVER
+ * - bit 1: USB
+ * - bit 0: Bluetooth icon
+ *
+ * byte 2:
+ * - bit 7: battery case
+ * - bit 6: MAX
+ * - bit 5: MIN
+ * - bit 4: HOLD
+ * - bit 3: digit 1, segment b and segment c
+ * - bit 2: digit 2, segment f
+ * - bit 1: digit 2, segment g
+ * - bit 0: digit 2, segment e
+ *
+ * byte 3:
+ * - bit 7: FAST
+ * - bit 6: digit 2, segment a
+ * - bit 5: digit 2, segment b
+ * - bit 4: digit 2, segment c
+ * - bit 3: digit 2, segment d
+ * - bit 2: digit 3, segment f
+ * - bit 1: digit 3, segment g
+ * - bot 0: digit 3, segment e
+ *
+ * byte 4:
+ * - bit 7: SLOW
+ * - bit 6: digit 3, segment a
+ * - bit 5: digit 3, segment b
+ * - bit 4: digit 3, segment c
+ * - bit 3: digit 3, segment d
+ * - bit 2: no segment
+ * - bit 1: no segment
+ * - bit 0: digit 3, segment dp
+ *
+ * byte 5:
+ * - bit 7: dBC
+ * - bit 6: digit 4, segment f
+ * - bit 5: digit 4, segment g
+ * - bit 4: digit 4, segment e
+ * - bit 3: dBA
+ * - bit 2: digit 4, segment a
+ * - bit 1: digit 4, segment b
+ * - bit 0: digit 4, segment c
+ *
+ * byte 6:
+ * - bit 7: digit 4, segment d
+ *
+ * all other bits can be set to any value
+ */
+// number of bytes in an LCD frame
+#define FRAME_SIZE (17U)
+
+/** which bit should be set to enable which segment in specific digits
+ *  @note 0 = byte 0 bit 0
+ */
+static const uint8_t digit_segments[4][8] = {
+	{ // digit 1
+		0, // a (segment does not exist)
+		16 + 3, // b
+		16 + 3, // c
+		0, // d (segment does not exist)
+		0, // e (segment does not exist)
+		0, // f (segment does not exist)
+		0, // g (segment does not exist)
+		0, // dp (segment does not exist)
+	},
+	{ // digit 2
+		24 + 6, // a
+		24 + 5, // b
+		24 + 4, // c
+		24 + 3, // d
+		16 + 0, // e
+		16 + 2, // f
+		16 + 1, // g
+		0, // dp (segment does not exist)
+	},
+	{ // digit 3
+		32 + 6, // a
+		32 + 5, // b
+		32 + 4, // c
+		32 + 3, // d
+		24 + 0, // e
+		24 + 2, // f
+		24 + 1, // g
+		0, // dp (actually 24 + 0 but we don't use it)
+	},
+	{ // digit 4
+		40 + 2, // a
+		40 + 1, // b
+		40 + 0, // c
+		48 + 7, // d
+		40 + 4, // e
+		40 + 6, // f
+		40 + 5, // g
+		0, // dp (segment does not exist)
+	},
+};
+
+/** the index corresponds to the digit to be displayed, the value represent the segments to be enabled
+ *  @note LSb = a, MSb = dp
+ */
+static const uint8_t number_segments[10] = {
+	0x3f, // 0: a b c d e f
+	0x06, // 1: b c
+	0x5b, // 2: a b d e g
+	0x4f, // 3: a b c d g
+	0x66, // 4: b c f g
+	0x6d, // 5: a c d f g
+	0x7d, // 6: a c d e f g
+	0x07, // 7: a b c
+	0x7f, // 8: a b c d e f g
+	0x6f, // 9; a c b d f g
+};
+
 /**
  * @brief USB string descriptor
  */
@@ -49,11 +180,58 @@ static const char* usb_str_desc[USB_STRING_DESCRIPTOR_ARRAY_SIZE] = {
 	CONFIG_TINYUSB_DESC_MANUFACTURER_STRING, // 1: Manufacturer
 	CONFIG_TINYUSB_DESC_PRODUCT_STRING,      // 2: Product
 	CONFIG_TINYUSB_DESC_SERIAL_STRING,       // 3: Serials, should use chip ID
-	CONFIG_TINYUSB_DESC_CDC_STRING,          // 4: CDC Interface
+	"GM1532 measurements",                   // 4: CDC Interface
 	"",                                      // 5: MSC Interface
 	"DFU (runtime mode)"                     // 6: DFU RT
 };
 
+static QueueHandle_t meas_queue; // queue for the measurement messages received
+#define MEAS_QUEUE_SIZE 4 // max number of control message received
+
+/* handle measurement received */
+static void meas_task(void *pvParameter)
+{
+	spi_slave_transaction_t t;
+	while (xQueueReceive(meas_queue, &t, portMAX_DELAY) == pdTRUE) {
+		const uint8_t* rx_buffer = t.rx_buffer; // t.rx_buffer is type-less
+		if (t.trans_len > 6 && 0xa0 == rx_buffer[0]) { // frame long enough for the LCD data
+			// extract digit segments
+			uint8_t segments[4] = {0}; // which digit segments are enabled
+			for (uint8_t digit = 0; digit < LENGTH(segments); digit++) {
+				segments[digit] = 0; // clear all segments
+				for (uint8_t seg = 0; seg < 8; seg++) {
+					if (rx_buffer[digit_segments[digit][seg] / 8] & (1 << (digit_segments[digit][seg] % 8))) {
+						segments[digit] |= (1 << seg);
+					}
+				}
+			}
+			// figure out digit value
+			uint8_t digits[4] = {0};
+			for (uint8_t digit = 0; digit < LENGTH(digits); digit++) {
+				for (uint8_t i = 0; i < LENGTH(number_segments); i++) {
+					if (number_segments[i] == segments[digit]) {
+						digits[digit] = i;
+					}
+				}
+			}
+			const uint16_t meas = digits[0] * 1000 + digits[1] * 100 + digits[2] * 10 + digits[3]; // in deci dBA
+			if (meas < 1400) { // ignore all segments on out of range values
+				printf("%u.%u dBA\n", meas / 10, meas % 10);
+			}
+		}
+	}
+}
+
+// called after LCD frame (e.g. SPI transaction) is received
+static uint8_t timeout = 0;
+void post_trans_cb(spi_slave_transaction_t *t) {
+	if (t) {
+		ESP_ERROR_CHECK( xQueueSend(meas_queue, t, 512) != pdTRUE ); // send measurement to be displayed
+		spi_slave_queue_trans(SPI2_HOST, t, portMAX_DELAY); // re-add transaction
+	}
+	timeout = 0; // reset timeout since we received data
+}
+
 void app_main(void)
 {
 	// check DFU force
@@ -105,6 +283,11 @@ void app_main(void)
 	ESP_ERROR_CHECK( tusb_dfu_rf_init() ); // configure DFU runtime (ensures we can use it)
 	ESP_LOGI(TAG, "USB initialized");
 
+	// task to decode and show the measurements
+	meas_queue = xQueueCreate(MEAS_QUEUE_SIZE, sizeof(spi_slave_transaction_t));
+	ESP_ERROR_CHECK( NULL == meas_queue );
+	xTaskCreate(meas_task, "meas_task", 2048, NULL, 4, NULL);
+
 	// configure SPI for GM1352 LCD data frame reading
 	const spi_bus_config_t buscfg = { // SPI bus configuration
 		.mosi_io_num = GPIO_MOSI,