AP_ToshibaCAN: rename millivolts to voltage_mv

also add some comments

libraries/AP_ToshibaCAN/AP_ToshibaCAN.cpp

@@ -313,7 +313,7 @@ void AP_ToshibaCAN::loop()
                     if (esc_id < TOSHIBACAN_MAX_NUM_ESCS) {
                         WITH_SEMAPHORE(_telem_sem);
                         _telemetry[esc_id].rpm = be16toh(reply_data.rpm);
-                        _telemetry[esc_id].millivolts = be16toh(reply_data.millivolts);
+                        _telemetry[esc_id].voltage_mv = be16toh(reply_data.voltage_mv);
                         _telemetry[esc_id].count++;
                         _telemetry[esc_id].new_data = true;
                         _esc_present_bitmask |= ((uint32_t)1 << esc_id);
@@ -431,7 +431,7 @@ void AP_ToshibaCAN::update()
             if (_telemetry[i].new_data) {
                 logger->Write_ESC(i, time_us,
                               _telemetry[i].rpm * 100U,
-                              _telemetry[i].millivolts * 0.1f,
+                              _telemetry[i].voltage_mv * 0.1f,
                               0,
                               _telemetry[i].temperature * 100.0f,
                               0);
@@ -481,7 +481,7 @@ void AP_ToshibaCAN::send_esc_telemetry_mavlink(uint8_t mav_chan)
             for (uint8_t j = 0; j < 4; j++) {
                 uint8_t esc_id = i * 4 + j;
                 temperature[j] = _telemetry[esc_id].temperature;
-                voltage[j] = _telemetry[esc_id].millivolts * 0.1f;
+                voltage[j] = _telemetry[esc_id].voltage_mv * 0.1f;
                 rpm[j] = _telemetry[esc_id].rpm;
                 count[j] = _telemetry[esc_id].count;
             }

libraries/AP_ToshibaCAN/AP_ToshibaCAN.h

@@ -69,10 +69,10 @@ private:
     // telemetry data (rpm, voltage)
     HAL_Semaphore _telem_sem;
     struct telemetry_info_t {
-        uint16_t rpm;
-        uint16_t millivolts;
-        uint16_t temperature;
-        uint16_t count;
+        uint16_t rpm;               // rpm
+        uint16_t voltage_mv;        // voltage in millivolts
+        uint16_t temperature;       // temperature in degrees
+        uint16_t count;             // total number of packets sent
         bool new_data;
     } _telemetry[TOSHIBACAN_MAX_NUM_ESCS];
     uint32_t _telemetry_req_ms;     // system time (in milliseconds) to request data from escs (updated at 10hz)
@@ -137,7 +137,7 @@ private:
             uint8_t state:7;
             uint16_t rpm;
             uint16_t reserved;
-            uint16_t millivolts;
+            uint16_t voltage_mv;    // voltage in millivolts
             uint8_t position_est_error;
         };
         uint8_t data[8];