# HG changeset patch
# User Michiel Broek <mbroek@mbse.eu>
# Date 1592139186 -7200
# Node ID 232f318a6b51660cccd30ad0e150d7aff4165519
# Parent  8c88a3d8ecf2f306dc37c2734dbd32faf616d85e
Code cleanup, doxygen comments added.

diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/co2meter.c
--- a/main/co2meter.c	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/co2meter.c	Sun Jun 14 14:53:06 2020 +0200
@@ -31,6 +31,9 @@
 extern uint32_t				err_connect;			///< Connect error counter
 
 
+/**
+ * @brief Main program entry
+ */
 void app_main()
 {
     esp_err_t           ret;
diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/config.c
--- a/main/config.c	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/config.c	Sun Jun 14 14:53:06 2020 +0200
@@ -27,7 +27,7 @@
     if (bytes != sizeof(config)) {
 	ESP_LOGE(TAG, "/spiffs/etc/config.conf written %d/%d bytes", bytes, sizeof(config));
     } else {
-	ESP_LOGI(TAG, "/spiffs/etc/config.conf written %d bytes", bytes);
+	ESP_LOGD(TAG, "/spiffs/etc/config.conf written %d bytes", bytes);
     }
 }
 
@@ -54,7 +54,7 @@
 	dst = (uint8_t*)&config;
 	size_t bytes = fread(dst, 1, sizeof(config), f);
 	fclose(f);
-	ESP_LOGI(TAG, "/spiffs/etc/config.conf read %d bytes", bytes);
+	ESP_LOGD(TAG, "/spiffs/etc/config.conf read %d bytes", bytes);
     }
 }
 
@@ -73,7 +73,7 @@
     if (bytes != sizeof(units)) {
         ESP_LOGE(TAG, "/spiffs/etc/units.conf written %d/%d bytes", bytes, sizeof(units));
     } else {
-        ESP_LOGI(TAG, "/spiffs/etc/units.conf written %d bytes", bytes);
+        ESP_LOGD(TAG, "/spiffs/etc/units.conf written %d bytes", bytes);
     }
 }
 
diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/task_ds18b20.c
--- a/main/task_ds18b20.c	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/task_ds18b20.c	Sun Jun 14 14:53:06 2020 +0200
@@ -56,7 +56,7 @@
     bool		found = false;
     EventBits_t         uxBits;
 
-    ESP_LOGI(TAG, "Starting DS18B20 sensors");
+    ESP_LOGI(TAG, "Start DS18B20 sensors");
     ds18b20_state = malloc(sizeof(DS18B20_State));
     ds18b20_state->valid = false;
     ds18b20_state->num_sensors = 0;
@@ -87,7 +87,7 @@
 	uxBits = xEventGroupWaitBits(xEventGroupDS18B20, TASK_DS18B20_REQUEST_TEMPS, pdFALSE, pdFALSE, portMAX_DELAY );
 	if (uxBits & TASK_DS18B20_REQUEST_TEMPS) {
 
-	    ESP_LOGI(TAG, "Requested DS18B20 readings");
+	    ESP_LOGD(TAG, "Requested DS18B20 readings");
 	    OneWireBus_ROMCode device_rom_codes[DS18B20_MAX] = {0};
 	    num_devices = 0;
 	    OneWireBus_SearchState search_state = {0};
diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/task_mqtt.c
--- a/main/task_mqtt.c	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/task_mqtt.c	Sun Jun 14 14:53:06 2020 +0200
@@ -18,8 +18,8 @@
 const int TASK_MQTT_DISCONNECT = BIT1;			///< Request MQTT disconnect
 const int TASK_MQTT_CONNECTED = BIT2;			///< MQTT is connected
 
-const char			*sensState[] = { "OK", "ERROR" };
-const char			*unitMode[] = { "OFF", "ON" };
+const char			*sensState[] = { "OK", "ERROR" };	///< Sensor state strings
+const char			*unitMode[] = { "OFF", "ON" };		///< Units state strings
 
 extern DS18B20_State            *ds18b20_state;         ///< DS18B20 state
 extern SemaphoreHandle_t        xSemaphoreDS18B20;      ///< DS18B20 lock semaphore
diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/task_user.c
--- a/main/task_user.c	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/task_user.c	Sun Jun 14 14:53:06 2020 +0200
@@ -709,7 +709,7 @@
 
 
 
-/*
+/**
  * @brief The counters display screen.
  */
 void screen_counters()
diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/u8g2_esp32_hal.c
--- a/main/u8g2_esp32_hal.c	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/u8g2_esp32_hal.c	Sun Jun 14 14:53:06 2020 +0200
@@ -1,3 +1,9 @@
+/**
+ * @file u8g2_esp32_hal.c
+ * @date Feb 12, 2017
+ * @author kolban
+ */
+
 #include <stdio.h>
 #include <string.h>
 
@@ -12,9 +18,9 @@
 static const char *TAG = "u8g2_hal";
 static const unsigned int I2C_TIMEOUT_MS = 1000;
 
-static spi_device_handle_t handle_spi;      // SPI handle.
-static i2c_cmd_handle_t    handle_i2c;      // I2C handle.
-static u8g2_esp32_hal_t    u8g2_esp32_hal;  // HAL state data.
+static spi_device_handle_t handle_spi;			///< SPI handle.
+static i2c_cmd_handle_t    handle_i2c;			///< I2C handle.
+static u8g2_esp32_hal_t    u8g2_esp32_hal;		///< HAL state data.
 static bool		   initialized = false;
 
 #undef ESP_ERROR_CHECK
@@ -31,204 +37,211 @@
  * HAL callback function as prescribed by the U8G2 library.  This callback is invoked
  * to handle SPI communications.
  */
-uint8_t u8g2_esp32_spi_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr) {
-	ESP_LOGD(TAG, "spi_byte_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
-	switch(msg) {
-		case U8X8_MSG_BYTE_SET_DC:
-			if (u8g2_esp32_hal.dc != U8G2_ESP32_HAL_UNDEFINED) {
-				gpio_set_level(u8g2_esp32_hal.dc, arg_int);
-			}
-			break;
-
-		case U8X8_MSG_BYTE_INIT: {
-			if (u8g2_esp32_hal.clk == U8G2_ESP32_HAL_UNDEFINED ||
-					u8g2_esp32_hal.mosi == U8G2_ESP32_HAL_UNDEFINED ||
-					u8g2_esp32_hal.cs == U8G2_ESP32_HAL_UNDEFINED) {
-				break;
-			}
+uint8_t u8g2_esp32_spi_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+    ESP_LOGD(TAG, "spi_byte_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
+    switch(msg) {
+	case U8X8_MSG_BYTE_SET_DC:
+		if (u8g2_esp32_hal.dc != U8G2_ESP32_HAL_UNDEFINED) {
+		    gpio_set_level(u8g2_esp32_hal.dc, arg_int);
+		}
+		break;
 
-		  spi_bus_config_t bus_config;
-                  memset(&bus_config, 0, sizeof(spi_bus_config_t));
-		  bus_config.sclk_io_num   = u8g2_esp32_hal.clk; // CLK
-		  bus_config.mosi_io_num   = u8g2_esp32_hal.mosi; // MOSI
-		  bus_config.miso_io_num   = -1; // MISO
-		  bus_config.quadwp_io_num = -1; // Not used
-		  bus_config.quadhd_io_num = -1; // Not used
-		  //ESP_LOGI(TAG, "... Initializing bus.");
-		  ESP_ERROR_CHECK(spi_bus_initialize(HSPI_HOST, &bus_config, 1));
-
-		  spi_device_interface_config_t dev_config;
-		  dev_config.address_bits     = 0;
-		  dev_config.command_bits     = 0;
-		  dev_config.dummy_bits       = 0;
-		  dev_config.mode             = 0;
-		  dev_config.duty_cycle_pos   = 0;
-		  dev_config.cs_ena_posttrans = 0;
-		  dev_config.cs_ena_pretrans  = 0;
-		  dev_config.clock_speed_hz   = 10000;
-		  dev_config.spics_io_num     = u8g2_esp32_hal.cs;
-		  dev_config.flags            = 0;
-		  dev_config.queue_size       = 200;
-		  dev_config.pre_cb           = NULL;
-		  dev_config.post_cb          = NULL;
-		  //ESP_LOGI(TAG, "... Adding device bus.");
-		  ESP_ERROR_CHECK(spi_bus_add_device(HSPI_HOST, &dev_config, &handle_spi));
-
-		  break;
+	case U8X8_MSG_BYTE_INIT: {
+		if (u8g2_esp32_hal.clk == U8G2_ESP32_HAL_UNDEFINED || u8g2_esp32_hal.mosi == U8G2_ESP32_HAL_UNDEFINED ||
+			u8g2_esp32_hal.cs == U8G2_ESP32_HAL_UNDEFINED) {
+		    break;
 		}
 
-		case U8X8_MSG_BYTE_SEND: {
-			spi_transaction_t trans_desc;
-			trans_desc.addr      = 0;
-			trans_desc.cmd   	 = 0;
-			trans_desc.flags     = 0;
-			trans_desc.length    = 8 * arg_int; // Number of bits NOT number of bytes.
-			trans_desc.rxlength  = 0;
-			trans_desc.tx_buffer = arg_ptr;
-			trans_desc.rx_buffer = NULL;
+		spi_bus_config_t bus_config;
+                memset(&bus_config, 0, sizeof(spi_bus_config_t));
+		bus_config.sclk_io_num   = u8g2_esp32_hal.clk; // CLK
+		bus_config.mosi_io_num   = u8g2_esp32_hal.mosi; // MOSI
+		bus_config.miso_io_num   = -1; // MISO
+		bus_config.quadwp_io_num = -1; // Not used
+		bus_config.quadhd_io_num = -1; // Not used
+		//ESP_LOGI(TAG, "... Initializing bus.");
+		ESP_ERROR_CHECK(spi_bus_initialize(HSPI_HOST, &bus_config, 1));
 
-			//ESP_LOGI(TAG, "... Transmitting %d bytes.", arg_int);
-			ESP_ERROR_CHECK(spi_device_transmit(handle_spi, &trans_desc));
-			break;
-		}
+		spi_device_interface_config_t dev_config;
+		dev_config.address_bits     = 0;
+		dev_config.command_bits     = 0;
+		dev_config.dummy_bits       = 0;
+		dev_config.mode             = 0;
+		dev_config.duty_cycle_pos   = 0;
+		dev_config.cs_ena_posttrans = 0;
+		dev_config.cs_ena_pretrans  = 0;
+		dev_config.clock_speed_hz   = 10000;
+		dev_config.spics_io_num     = u8g2_esp32_hal.cs;
+		dev_config.flags            = 0;
+		dev_config.queue_size       = 200;
+		dev_config.pre_cb           = NULL;
+		dev_config.post_cb          = NULL;
+		//ESP_LOGI(TAG, "... Adding device bus.");
+		ESP_ERROR_CHECK(spi_bus_add_device(HSPI_HOST, &dev_config, &handle_spi));
+
+		break;
 	}
-	return 0;
-} // u8g2_esp32_spi_byte_cb
+
+	case U8X8_MSG_BYTE_SEND: {
+		spi_transaction_t trans_desc;
+		trans_desc.addr      = 0;
+		trans_desc.cmd       = 0;
+		trans_desc.flags     = 0;
+		trans_desc.length    = 8 * arg_int; // Number of bits NOT number of bytes.
+		trans_desc.rxlength  = 0;
+		trans_desc.tx_buffer = arg_ptr;
+		trans_desc.rx_buffer = NULL;
+
+		//ESP_LOGI(TAG, "... Transmitting %d bytes.", arg_int);
+		ESP_ERROR_CHECK(spi_device_transmit(handle_spi, &trans_desc));
+		break;
+	}
+    }
+    return 0;
+}
+
+
 
 /*
  * HAL callback function as prescribed by the U8G2 library.  This callback is invoked
  * to handle I2C communications.
  */
-uint8_t u8g2_esp32_i2c_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr) {
-	ESP_LOGD(TAG, "i2c_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
-
-	switch(msg) {
-		case U8X8_MSG_BYTE_SET_DC: {
-			if (u8g2_esp32_hal.dc != U8G2_ESP32_HAL_UNDEFINED) {
-				gpio_set_level(u8g2_esp32_hal.dc, arg_int);
-			}
-			break;
+uint8_t u8g2_esp32_i2c_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+    ESP_LOGD(TAG, "i2c_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
+    switch(msg) {
+	case U8X8_MSG_BYTE_SET_DC: {
+		if (u8g2_esp32_hal.dc != U8G2_ESP32_HAL_UNDEFINED) {
+		    gpio_set_level(u8g2_esp32_hal.dc, arg_int);
 		}
+		break;
+	}
 
-		case U8X8_MSG_BYTE_INIT: {
-			if (u8g2_esp32_hal.sda == U8G2_ESP32_HAL_UNDEFINED ||
-					u8g2_esp32_hal.scl == U8G2_ESP32_HAL_UNDEFINED || initialized) { // here i test if already initialized, if it's the case don't do it again!
-				break;
-			}
-
-		    i2c_config_t conf;
-		    conf.mode = I2C_MODE_MASTER;
-		    conf.sda_io_num = u8g2_esp32_hal.sda;
-		    conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
-		    conf.scl_io_num = u8g2_esp32_hal.scl;
-		    conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
-		    conf.master.clk_speed = I2C_MASTER_FREQ_HZ;
-		    ESP_ERROR_CHECK(i2c_param_config(I2C_MASTER_NUM, &conf));
-		    ESP_LOGI(TAG, "I2C gpio_sda: %d gpio_scl: %d clk_speed: %d master_num: %d",
-			u8g2_esp32_hal.sda, u8g2_esp32_hal.scl, I2C_MASTER_FREQ_HZ, I2C_MASTER_NUM);
-		    ESP_ERROR_CHECK(i2c_driver_install(I2C_MASTER_NUM, conf.mode, I2C_MASTER_RX_BUF_DISABLE, I2C_MASTER_TX_BUF_DISABLE, 0));
-		    initialized=true;
-			break;
+	case U8X8_MSG_BYTE_INIT: {
+		if (u8g2_esp32_hal.sda == U8G2_ESP32_HAL_UNDEFINED || u8g2_esp32_hal.scl == U8G2_ESP32_HAL_UNDEFINED || initialized) {
+		    // here i test if already initialized, if it's the case don't do it again!
+		    break;
 		}
 
-		case U8X8_MSG_BYTE_SEND: {
-			uint8_t* data_ptr = (uint8_t*)arg_ptr;
-			ESP_LOG_BUFFER_HEXDUMP(TAG, data_ptr, arg_int, ESP_LOG_VERBOSE);
+		i2c_config_t conf;
+		conf.mode = I2C_MODE_MASTER;
+		conf.sda_io_num = u8g2_esp32_hal.sda;
+		conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
+		conf.scl_io_num = u8g2_esp32_hal.scl;
+		conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
+		conf.master.clk_speed = I2C_MASTER_FREQ_HZ;
+		ESP_ERROR_CHECK(i2c_param_config(I2C_MASTER_NUM, &conf));
+		ESP_LOGI(TAG, "I2C gpio_sda: %d gpio_scl: %d clk_speed: %d master_num: %d",
+			u8g2_esp32_hal.sda, u8g2_esp32_hal.scl, I2C_MASTER_FREQ_HZ, I2C_MASTER_NUM);
+		ESP_ERROR_CHECK(i2c_driver_install(I2C_MASTER_NUM, conf.mode, I2C_MASTER_RX_BUF_DISABLE, I2C_MASTER_TX_BUF_DISABLE, 0));
+		initialized = true;
+		break;
+	}
 
-			while( arg_int > 0 ) {
-			   ESP_ERROR_CHECK(i2c_master_write_byte(handle_i2c, *data_ptr, ACK_CHECK_EN));
-			   data_ptr++;
-			   arg_int--;
-			}
-			break;
-		}
+	case U8X8_MSG_BYTE_SEND: {
+		uint8_t* data_ptr = (uint8_t*)arg_ptr;
+		ESP_LOG_BUFFER_HEXDUMP(TAG, data_ptr, arg_int, ESP_LOG_VERBOSE);
 
-		case U8X8_MSG_BYTE_START_TRANSFER: {
-			uint8_t i2c_address = u8x8_GetI2CAddress(u8x8);
-			handle_i2c = i2c_cmd_link_create();
-			ESP_LOGD(TAG, "Start I2C transfer to %02X.", i2c_address>>1);
-			ESP_ERROR_CHECK(i2c_master_start(handle_i2c));
-			ESP_ERROR_CHECK(i2c_master_write_byte(handle_i2c, i2c_address | I2C_MASTER_WRITE, ACK_CHECK_EN));
-			break;
+		while( arg_int > 0 ) {
+		    ESP_ERROR_CHECK(i2c_master_write_byte(handle_i2c, *data_ptr, ACK_CHECK_EN));
+		    data_ptr++;
+		    arg_int--;
 		}
+		break;
+	}
 
-		case U8X8_MSG_BYTE_END_TRANSFER: {
-			ESP_LOGD(TAG, "End I2C transfer.");
-			ESP_ERROR_CHECK(i2c_master_stop(handle_i2c));
-			ESP_ERROR_CHECK(i2c_master_cmd_begin(I2C_MASTER_NUM, handle_i2c, I2C_TIMEOUT_MS / portTICK_RATE_MS));
-			i2c_cmd_link_delete(handle_i2c);
-			break;
-		}
+	case U8X8_MSG_BYTE_START_TRANSFER: {
+		uint8_t i2c_address = u8x8_GetI2CAddress(u8x8);
+		handle_i2c = i2c_cmd_link_create();
+		ESP_LOGD(TAG, "Start I2C transfer to %02X.", i2c_address>>1);
+		ESP_ERROR_CHECK(i2c_master_start(handle_i2c));
+		ESP_ERROR_CHECK(i2c_master_write_byte(handle_i2c, i2c_address | I2C_MASTER_WRITE, ACK_CHECK_EN));
+		break;
 	}
-	return 0;
-} // u8g2_esp32_i2c_byte_cb
+
+	case U8X8_MSG_BYTE_END_TRANSFER: {
+		ESP_LOGD(TAG, "End I2C transfer.");
+		ESP_ERROR_CHECK(i2c_master_stop(handle_i2c));
+		ESP_ERROR_CHECK(i2c_master_cmd_begin(I2C_MASTER_NUM, handle_i2c, I2C_TIMEOUT_MS / portTICK_RATE_MS));
+		i2c_cmd_link_delete(handle_i2c);
+		break;
+	}
+    }
+    return 0;
+}
+
+
 
 /*
  * HAL callback function as prescribed by the U8G2 library.  This callback is invoked
  * to handle callbacks for GPIO and delay functions.
  */
-uint8_t u8g2_esp32_gpio_and_delay_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr) {
-	ESP_LOGD(TAG, "gpio_and_delay_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
-
-	switch(msg) {
+uint8_t u8g2_esp32_gpio_and_delay_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+    ESP_LOGD(TAG, "gpio_and_delay_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
+    switch(msg) {
 	// Initialize the GPIO and DELAY HAL functions.  If the pins for DC and RESET have been
 	// specified then we define those pins as GPIO outputs.
-		case U8X8_MSG_GPIO_AND_DELAY_INIT: {
-			uint64_t bitmask = 0;
-			if (u8g2_esp32_hal.dc != U8G2_ESP32_HAL_UNDEFINED) {
-				bitmask = bitmask | (1ull<<u8g2_esp32_hal.dc);
-			}
-			if (u8g2_esp32_hal.reset != U8G2_ESP32_HAL_UNDEFINED) {
-				bitmask = bitmask | (1ull<<u8g2_esp32_hal.reset);
-			}
-			if (u8g2_esp32_hal.cs != U8G2_ESP32_HAL_UNDEFINED) {
-				bitmask = bitmask | (1ull<<u8g2_esp32_hal.cs);
-			}
+	case U8X8_MSG_GPIO_AND_DELAY_INIT: {
+		uint64_t bitmask = 0;
+		if (u8g2_esp32_hal.dc != U8G2_ESP32_HAL_UNDEFINED) {
+		    bitmask = bitmask | (1ull<<u8g2_esp32_hal.dc);
+		}
+		if (u8g2_esp32_hal.reset != U8G2_ESP32_HAL_UNDEFINED) {
+		    bitmask = bitmask | (1ull<<u8g2_esp32_hal.reset);
+		}
+		if (u8g2_esp32_hal.cs != U8G2_ESP32_HAL_UNDEFINED) {
+		    bitmask = bitmask | (1ull<<u8g2_esp32_hal.cs);
+		}
 
-            if (bitmask==0) {
-            	break;
-            }
-			gpio_config_t gpioConfig;
-			gpioConfig.pin_bit_mask = bitmask;
-			gpioConfig.mode         = GPIO_MODE_OUTPUT;
-			gpioConfig.pull_up_en   = GPIO_PULLUP_DISABLE;
-			gpioConfig.pull_down_en = GPIO_PULLDOWN_ENABLE;
-			gpioConfig.intr_type    = GPIO_INTR_DISABLE;
-			gpio_config(&gpioConfig);
-			break;
-		}
+       		if (bitmask==0) {
+            	    break;
+           	}
+		gpio_config_t gpioConfig;
+		gpioConfig.pin_bit_mask = bitmask;
+		gpioConfig.mode         = GPIO_MODE_OUTPUT;
+		gpioConfig.pull_up_en   = GPIO_PULLUP_DISABLE;
+		gpioConfig.pull_down_en = GPIO_PULLDOWN_ENABLE;
+		gpioConfig.intr_type    = GPIO_INTR_DISABLE;
+		gpio_config(&gpioConfig);
+		break;
+	}
 
 	// Set the GPIO reset pin to the value passed in through arg_int.
-		case U8X8_MSG_GPIO_RESET:
-			if (u8g2_esp32_hal.reset != U8G2_ESP32_HAL_UNDEFINED) {
-				gpio_set_level(u8g2_esp32_hal.reset, arg_int);
-			}
-			break;
+	case U8X8_MSG_GPIO_RESET:
+		if (u8g2_esp32_hal.reset != U8G2_ESP32_HAL_UNDEFINED) {
+		    gpio_set_level(u8g2_esp32_hal.reset, arg_int);
+		}
+		break;
+
 	// Set the GPIO client select pin to the value passed in through arg_int.
-		case U8X8_MSG_GPIO_CS:
-			if (u8g2_esp32_hal.cs != U8G2_ESP32_HAL_UNDEFINED) {
-				gpio_set_level(u8g2_esp32_hal.cs, arg_int);
-			}
-			break;
+	case U8X8_MSG_GPIO_CS:
+		if (u8g2_esp32_hal.cs != U8G2_ESP32_HAL_UNDEFINED) {
+		    gpio_set_level(u8g2_esp32_hal.cs, arg_int);
+		}
+		break;
+
 	// Set the Software I²C pin to the value passed in through arg_int.
-		case U8X8_MSG_GPIO_I2C_CLOCK:
-			if (u8g2_esp32_hal.scl != U8G2_ESP32_HAL_UNDEFINED) {
-				gpio_set_level(u8g2_esp32_hal.scl, arg_int);
-//				printf("%c",(arg_int==1?'C':'c'));
-			}
-			break;
+	case U8X8_MSG_GPIO_I2C_CLOCK:
+		if (u8g2_esp32_hal.scl != U8G2_ESP32_HAL_UNDEFINED) {
+		    gpio_set_level(u8g2_esp32_hal.scl, arg_int);
+//		    printf("%c",(arg_int==1?'C':'c'));
+		}
+		break;
+
 	// Set the Software I²C pin to the value passed in through arg_int.
-		case U8X8_MSG_GPIO_I2C_DATA:
-			if (u8g2_esp32_hal.sda != U8G2_ESP32_HAL_UNDEFINED) {
-				gpio_set_level(u8g2_esp32_hal.sda, arg_int);
-//				printf("%c",(arg_int==1?'D':'d'));
-			}
-			break;
+	case U8X8_MSG_GPIO_I2C_DATA:
+		if (u8g2_esp32_hal.sda != U8G2_ESP32_HAL_UNDEFINED) {
+		    gpio_set_level(u8g2_esp32_hal.sda, arg_int);
+//		    printf("%c",(arg_int==1?'D':'d'));
+		}
+		break;
 
 	// Delay for the number of milliseconds passed in through arg_int.
-		case U8X8_MSG_DELAY_MILLI:
-			vTaskDelay(arg_int/portTICK_PERIOD_MS);
-			break;
-	}
-	return 0;
-} // u8g2_esp32_gpio_and_delay_cb
+	case U8X8_MSG_DELAY_MILLI:
+		vTaskDelay(arg_int/portTICK_PERIOD_MS);
+		break;
+    }
+    return 0;
+}
diff -r 8c88a3d8ecf2 -r 232f318a6b51 main/u8g2_esp32_hal.h
--- a/main/u8g2_esp32_hal.h	Sat Jun 13 23:16:50 2020 +0200
+++ b/main/u8g2_esp32_hal.h	Sun Jun 14 14:53:06 2020 +0200
@@ -12,29 +12,47 @@
 #include "driver/spi_master.h"
 #include "driver/i2c.h"
 
-#define U8G2_ESP32_HAL_UNDEFINED (-1)
+#define U8G2_ESP32_HAL_UNDEFINED	(-1)			///<  Undefined value for this HAL
 
-#define I2C_MASTER_NUM	(CONFIG_I2C_MASTER_PORT_NUM)	///<  I2C port number for master dev (original 1)
-#define I2C_MASTER_TX_BUF_DISABLE   0      ///<  I2C master do not need buffer
-#define I2C_MASTER_RX_BUF_DISABLE   0      ///<  I2C master do not need buffer
+#define I2C_MASTER_NUM	(CONFIG_I2C_MASTER_PORT_NUM)		///<  I2C port number for master dev (original 1)
+#define I2C_MASTER_TX_BUF_DISABLE	0			///<  I2C master do not need buffer
+#define I2C_MASTER_RX_BUF_DISABLE	0			///<  I2C master do not need buffer
 #define I2C_MASTER_FREQ_HZ	(CONFIG_I2C_MASTER_FREQUENCY)	///<  I2C master clock frequency (original 50000)
-#define ACK_CHECK_EN   0x1                 ///<  I2C master will check ack from slave
-#define ACK_CHECK_DIS  0x0                 ///<  I2C master will not check ack from slave
+#define ACK_CHECK_EN			0x1			///<  I2C master will check ack from slave
+#define ACK_CHECK_DIS			0x0			///<  I2C master will not check ack from slave
 
 typedef struct {
-	gpio_num_t clk;
-	gpio_num_t mosi;
-	gpio_num_t sda; // data for I²C
-	gpio_num_t scl; // clock for I²C
-	gpio_num_t cs;
-	gpio_num_t reset;
+	gpio_num_t clk;				///< SPI clock
+	gpio_num_t mosi;			///< SPI mosi
+	gpio_num_t sda;				///< data for I²C
+	gpio_num_t scl;				///< clock for I²C
+	gpio_num_t cs;				///< SPI cs
+	gpio_num_t reset;			///< SPI reset
 	gpio_num_t dc;
-} u8g2_esp32_hal_t ;
+} u8g2_esp32_hal_t;				///< HAL structure
 
 #define U8G2_ESP32_HAL_DEFAULT {U8G2_ESP32_HAL_UNDEFINED, U8G2_ESP32_HAL_UNDEFINED, U8G2_ESP32_HAL_UNDEFINED, U8G2_ESP32_HAL_UNDEFINED, U8G2_ESP32_HAL_UNDEFINED, U8G2_ESP32_HAL_UNDEFINED, U8G2_ESP32_HAL_UNDEFINED }
 
+/**
+ * @brief Initialze the ESP32 HAL.
+ */
 void u8g2_esp32_hal_init(u8g2_esp32_hal_t u8g2_esp32_hal_param);
+
+/**
+ * @brief HAL callback function as prescribed by the U8G2 library.
+ *        This callback is invoked to handle SPI communications.
+ */
 uint8_t u8g2_esp32_spi_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr);
+
+/**
+ * @brief HAL callback function as prescribed by the U8G2 library.
+ *        This callback is invoked to handle I2C communications.
+ */
 uint8_t u8g2_esp32_i2c_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr);
+
+/**
+ * @brief HAL callback function as prescribed by the U8G2 library.
+ *        This callback is invoked to handle callbacks for GPIO and delay functions.
+ */
 uint8_t u8g2_esp32_gpio_and_delay_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr);
 #endif /* U8G2_ESP32_HAL_H_ */
diff -r 8c88a3d8ecf2 -r 232f318a6b51 sdkconfig
--- a/sdkconfig	Sat Jun 13 23:16:50 2020 +0200
+++ b/sdkconfig	Sun Jun 14 14:53:06 2020 +0200
@@ -20,11 +20,11 @@
 # CONFIG_APP_EXCLUDE_PROJECT_NAME_VAR is not set
 # CONFIG_BOOTLOADER_LOG_LEVEL_NONE is not set
 # CONFIG_BOOTLOADER_LOG_LEVEL_ERROR is not set
-CONFIG_BOOTLOADER_LOG_LEVEL_WARN=y
-# CONFIG_BOOTLOADER_LOG_LEVEL_INFO is not set
+# CONFIG_BOOTLOADER_LOG_LEVEL_WARN is not set
+CONFIG_BOOTLOADER_LOG_LEVEL_INFO=y
 # CONFIG_BOOTLOADER_LOG_LEVEL_DEBUG is not set
 # CONFIG_BOOTLOADER_LOG_LEVEL_VERBOSE is not set
-CONFIG_BOOTLOADER_LOG_LEVEL=2
+CONFIG_BOOTLOADER_LOG_LEVEL=3
 # CONFIG_BOOTLOADER_VDDSDIO_BOOST_1_8V is not set
 CONFIG_BOOTLOADER_VDDSDIO_BOOST_1_9V=y
 # CONFIG_BOOTLOADER_FACTORY_RESET is not set
@@ -559,11 +559,11 @@
 CONFIG_TOOLPREFIX="xtensa-esp32-elf-"
 # CONFIG_LOG_BOOTLOADER_LEVEL_NONE is not set
 # CONFIG_LOG_BOOTLOADER_LEVEL_ERROR is not set
-CONFIG_LOG_BOOTLOADER_LEVEL_WARN=y
-# CONFIG_LOG_BOOTLOADER_LEVEL_INFO is not set
+# CONFIG_LOG_BOOTLOADER_LEVEL_WARN is not set
+CONFIG_LOG_BOOTLOADER_LEVEL_INFO=y
 # CONFIG_LOG_BOOTLOADER_LEVEL_DEBUG is not set
 # CONFIG_LOG_BOOTLOADER_LEVEL_VERBOSE is not set
-CONFIG_LOG_BOOTLOADER_LEVEL=2
+CONFIG_LOG_BOOTLOADER_LEVEL=3
 # CONFIG_APP_ROLLBACK_ENABLE is not set
 # CONFIG_FLASH_ENCRYPTION_ENABLED is not set
 # CONFIG_FLASHMODE_QIO is not set