Battery voltage read implemented (TTGOv2.1)

README.md

@@ -221,11 +221,15 @@ device answers with it's current configuration. The configuration is a C structu
 
 0x81 get device uptime
 
-	bytes 1-7:		Uptime in seconds (little endian format)
+	bytes 1-7:		uptime in seconds (little endian format)
 
 0x82 get device cpu temperature
 
-	bytes 1-3:		chip temperature in celsius (little endian format)
+	bytes 1-3:		chip temperature in degrees celsius (little endian format)
+
+0x83 get device battery voltage
+
+	bytes 1-4:		battery voltage in millivolt, 0 if unreadable (little endian format)
 
 # License
 

platformio.ini

@@ -11,7 +11,7 @@
 
 ; ---> SELECT TARGET PLATFORM HERE! <---
 [platformio]
-env_default = heltec
+;env_default = heltec
 ;env_default = ttgov1
 ;env_default = ttgov2
 ;env_default = ttgov21

src/adcread.cpp

@@ -0,0 +1,89 @@
+#ifdef HAS_BATTERY_PROBE
+
+/* ADC1 Example
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+
+#include "globals.h"
+
+#include <driver/adc.h>
+#include <esp_adc_cal.h>
+
+#define DEFAULT_VREF    1100        // we use adc2_vref_to_gpio() to obtain a better estimate
+#define NO_OF_SAMPLES   64          // we do multisampling
+
+// Local logging tag
+static const char TAG[] = "main";
+
+static const adc_channel_t channel = (adc_channel_t) HAS_BATTERY_PROBE;
+static const adc_atten_t atten = ADC_ATTEN_DB_0;
+static const adc_unit_t unit = ADC_UNIT_1;
+
+static void check_efuse()
+{
+    //Check if two point calibration values are burned into eFuse
+    if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP) == ESP_OK) {
+        ESP_LOGI(TAG,"eFuse Two Point: Supported");
+    } else {
+        ESP_LOGI(TAG,"eFuse Two Point: NOT supported");
+    }
+
+    //Check Vref is burned into eFuse
+    if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_VREF) == ESP_OK) {
+        ESP_LOGI(TAG,"eFuse Vref: Supported");
+    } else {
+        ESP_LOGI(TAG,"eFuse Vref: NOT supported");
+    }
+}
+
+static void print_char_val_type(esp_adc_cal_value_t val_type)
+{
+    if (val_type == ESP_ADC_CAL_VAL_EFUSE_TP) {
+        ESP_LOGI(TAG,"Characterized using Two Point Value");
+    } else if (val_type == ESP_ADC_CAL_VAL_EFUSE_VREF) {
+        ESP_LOGI(TAG,"Characterized using eFuse Vref");
+    } else {
+        ESP_LOGI(TAG,"Characterized using Default Vref");
+    }
+}
+
+uint16_t read_voltage(void)
+{
+    //Check if Two Point or Vref are burned into eFuse
+    check_efuse();
+
+    //Configure ADC
+    if (unit == ADC_UNIT_1) {
+        adc1_config_width(ADC_WIDTH_BIT_12);
+        adc1_config_channel_atten((adc1_channel_t)channel, atten);
+    } else {
+        adc2_config_channel_atten((adc2_channel_t)channel, atten);
+    }
+
+    //Characterize ADC
+    esp_adc_cal_characteristics_t *adc_chars = (esp_adc_cal_characteristics_t *) calloc(1, sizeof(esp_adc_cal_characteristics_t));
+    esp_adc_cal_value_t val_type = esp_adc_cal_characterize(unit, atten, ADC_WIDTH_BIT_12, DEFAULT_VREF, adc_chars);
+    print_char_val_type(val_type);
+
+    //sample ADC
+    uint32_t adc_reading = 0;
+    //Multisampling
+    for (int i = 0; i < NO_OF_SAMPLES; i++) {
+        if (unit == ADC_UNIT_1) {
+            adc_reading += adc1_get_raw((adc1_channel_t)channel);
+        } else {
+            int raw;
+            adc2_get_raw((adc2_channel_t)channel, ADC_WIDTH_BIT_12, &raw);
+            adc_reading += raw;
+        }
+    }
+    adc_reading /= NO_OF_SAMPLES;
+    //Convert adc_reading to voltage in mV
+    uint32_t voltage = esp_adc_cal_raw_to_voltage(adc_reading, adc_chars);
+    ESP_LOGI(TAG,"Raw: %d\tVoltage: %dmV", adc_reading, voltage);
+    return voltage;
+}
+#endif // HAS_BATTERY_PROBE

src/hal/ttgov21.h

@@ -5,6 +5,7 @@
 #define HAS_DISPLAY U8X8_SSD1306_128X64_NONAME_HW_I2C
 #define DISPLAY_FLIP  1 // rotated display
 #define HAS_LED 23 // green on board LED_G3 (not in initial board version)
+#define HAS_BATTERY_PROBE ADC1_GPIO35_CHANNEL // battery probe GPIO pin -> ADC_CHANNEL_7
 
 // re-define pin definitions of pins_arduino.h
 #define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input

src/main.h

@@ -1,6 +1,6 @@
 
 // program version - note: increment version after modifications to configData_t struct!!
-#define PROGVERSION                     "1.3.7"    // use max 10 chars here!
+#define PROGVERSION                     "1.3.71"    // use max 10 chars here!
 #define PROGNAME                        "PAXCNT"
 
 //--- Declarations ---

src/rcommand.cpp

@@ -24,6 +24,12 @@ typedef struct {
     void antenna_select(const uint8_t _ant);
 #endif
 
+// function defined in adcread.cpp
+#ifdef HAS_BATTERY_PROBE
+    uint32_t read_voltage(void);
+#endif
+
+
 // help function to assign LoRa datarates to numeric spreadfactor values
 void switch_lora (uint8_t sf, uint8_t tx) {
     if ( tx > 20 ) return;
@@ -235,6 +241,21 @@ void get_cputemp (uint8_t val) {
     ESP_LOGI(TAG, "%d bytes queued in send queue", size-1);
 };
 
+void get_voltage (uint8_t val) {
+    ESP_LOGI(TAG, "Remote command: get battery voltage");
+    #ifdef HAS_BATTERY_PROBE
+        uint32_t voltage = read_voltage();
+    #else
+        uint32_t voltage = 0;
+    #endif
+    int size = sizeof(voltage);
+    unsigned char *sendData = new unsigned char[size];
+    memcpy(sendData, (unsigned char*)&voltage, size);
+    LMIC_setTxData2(RCMDPORT, sendData, size-1, 0); // send data unconfirmed on RCMD Port
+    delete sendData; // free memory
+    ESP_LOGI(TAG, "%d bytes queued in send queue", size-1);
+};
+
 // assign previously defined functions to set of numeric remote commands
 // format: opcode, function, flag (1 = do make settings persistent / 0 = don't)
 // 
@@ -257,7 +278,8 @@ cmd_t table[] = {
                 {0x10, set_rgblum, true},
                 {0x80, get_config, false},
                 {0x81, get_uptime, false},
-                {0x82, get_cputemp, false}
+                {0x82, get_cputemp, false},
+                {0x83, get_voltage, false}
                 };
 
 // check and execute remote command