GPS - Read/discard approach, add nmea rates to hardware

Author: brentru

src/components/gps/controller.cpp

@@ -77,5 +77,28 @@ void GPSController::update() {
 
     // Did read period elapse?
     ulong cur_time = millis();
-  }
-}
+    if (cur_time - drv->GetPollPeriodPrv() < drv->GetPollPeriod())
+      continue; // Not yet elapsed, skip this driver
+
+    // Discard the GPS buffer before we attempt to do a fresh read
+    size_t bytes_avail = drv->GetAdaGps()->available();
+    if (bytes_avail > 0) {
+      // TODO: Remove these two WS_DEBUG_PRINTs!
+      WS_DEBUG_PRINT("[gps] Discarding GPS data: ");
+      WS_DEBUG_PRINTLN(bytes_avail);
+      // Read the available data from the GPS module
+      // and discard it
+      for (size_t i = 0; i < bytes_avail; i++) {
+        drv->GetAdaGps()->read();
+      }
+    }
+
+    // Unset the received flag
+    if (drv->GetAdaGps()->newNMEAreceived()) {
+      drv->GetAdaGps()->lastNMEA();
+    }
+
+    // Let's attempt to get a sentence from the GPS module
+    // TODO: Are we expecting RMC, GGA, or other sentences?
+    // TODO: Use a timeout for the read here
+  }

src/components/gps/hardware.cpp

@@ -40,6 +40,12 @@ GPSHardware::~GPSHardware() {
  * @returns True if the message was handled successfully, False otherwise.
  */
 bool GPSHardware::Handle_GPSConfig(wippersnapper_gps_GPSConfig *gps_config) {
+  WS_DEBUG_PRINTLN("[gps] Handling GPSConfig message...");
+  if (gps_config == nullptr)
+    return false;
+  // Set the polling period for GPS data
+  SetPollPeriod(gps_config->period);
+
   // Attempt to decode the GPSConfig message
   if (_driver_type == GPS_DRV_MTK) {
     WS_DEBUG_PRINTLN("[gps] Handling GPSConfig for MediaTek driver...");
@@ -206,6 +212,8 @@ bool GPSHardware::DetectMediatek() {
     return false;
   }
   _driver_type = GPS_DRV_MTK;
+  _nmea_baud_rate = DEFAULT_MTK_NMEA_BAUD_RATE;
+  _nmea_update_rate = DEFAULT_MTK_NMEA_UPDATE_RATE;
   return true;
 }
 
@@ -231,7 +239,13 @@ bool GPSHardware::BuildPmtkAck(char *msg_cmd, char *msg_resp) {
  * @param poll_period
  *        The polling period in milliseconds.
  */
-void GPSHardware::SetPollPeriod(ulong poll_period) { _period = poll_period; }
+void GPSHardware::SetPollPeriod(ulong poll_period) {
+  if (poll_period < 0) {
+    _period = 0;
+    return;
+  }
+  _period = (unsigned long)(poll_period * 1000.0f);
+}
 
 /*!
  * @brief Sets the previous polling period for GPS data.
@@ -252,4 +266,40 @@ ulong GPSHardware::GetPollPeriod() { return _period; }
  * @brief Gets the previous polling period for GPS data.
  * @returns The previous polling period in milliseconds.
  */
-ulong GPSHardware::GetPollPeriodPrv() { return _period_prv; }
+ulong GPSHardware::GetPollPeriodPrv() { return _period_prv; }
+
+/*!
+ * @brief Returns the Adafruit_GPS instance.
+ * @returns Pointer to the Adafruit_GPS instance.
+ */
+Adafruit_GPS *GPSHardware::GetAdaGps() { return _ada_gps; }
+
+/*!
+ * @brief Sets the NMEA update rate for GPS data.
+ * @param nmea_update_rate
+ *        The NMEA update rate, in Hz.
+ */
+void GPSHardware::SetNmeaUpdateRate(int nmea_update_rate) {
+  _nmea_update_rate = nmea_update_rate;
+}
+
+/*!
+ * @brief Returns the NMEA port update rate for GPS data.
+ * @returns The NMEA update rate, in Hz.
+ */
+int GPSHardware::GetNmeaUpdateRate() { return _nmea_update_rate; }
+
+/*!
+ * @brief Sets the NMEA baud rate for GPS data.
+ * @param nmea_baud_rate
+ *        The NMEA baud rate, in bits per second.
+ */
+void GPSHardware::SetNmeaBaudRate(int nmea_baud_rate) {
+  _nmea_baud_rate = nmea_baud_rate;
+}
+
+/*!
+ * @brief Returns the NMEA port baud rate for GPS data.
+ * @returns The NMEA baud rate, in bits per second.
+ */
+int GPSHardware::GetNmeaBaudRate() { return _nmea_baud_rate; }

src/components/gps/hardware.h

@@ -22,7 +22,9 @@
 #define CMD_MTK_QUERY_FW_RESP                                                  \
   "$PMTK705" ///< Response from querying MediaTek firmware version without the
              ///< ReleaseStr
-#define MAX_NEMA_SENTENCE_LEN 82 ///< Maximum length of a NMEA sentence
+#define DEFAULT_MTK_NMEA_UPDATE_RATE 1  ///< Default NMEA update rate in Hz
+#define DEFAULT_MTK_NMEA_BAUD_RATE 9600 ///< Default NMEA baud rate in bits per
+#define MAX_NEMA_SENTENCE_LEN 82        ///< Maximum length of a NMEA sentence
 
 class Wippersnapper_V2; ///< Forward declaration
 class UARTHardware;     ///< Forward declaration
@@ -57,8 +59,13 @@ class GPSHardware {
   void SetPollPeriodPrv(ulong poll_period_prv);
   ulong GetPollPeriod();
   ulong GetPollPeriodPrv();
+  void SetNmeaUpdateRate(int nmea_update_rate);
+  int GetNmeaUpdateRate();
+  void SetNmeaBaudRate(int nmea_baud_rate);
+  int GetNmeaBaudRate();
   // TODO: Add SetInterface(I2C *_i2c_hardware) for I2C support here!
   bool Handle_GPSConfig(wippersnapper_gps_GPSConfig *gps_config);
+  Adafruit_GPS *GetAdaGps();
 
 private:
   bool QueryModuleType();
@@ -68,10 +75,12 @@ class GPSHardware {
   GpsDriverType _driver_type;           ///< Type of GPS driver used
   HardwareSerial *_hw_serial = nullptr; ///< HardwareSerial instance for GPS;
   Adafruit_GPS *_ada_gps = nullptr;     ///< Adafruit GPS instance
-  ulong _period;     ///< Polling period for GPS data (Specified by IO), in
-                     ///< milliseconds
-  ulong _period_prv; ///< Previous period for GPS data (Specified by IO), in
-                     ///< milliseconds
+  ulong _period;         ///< Polling period for GPS data (Specified by IO), in
+                         ///< milliseconds
+  ulong _period_prv;     ///< Previous period for GPS data (Specified by IO), in
+                         ///< milliseconds
+  int _nmea_update_rate; ///< NMEA update rate for GPS data, in Hz
+  int _nmea_baud_rate;   ///< NMEA baud rate for GPS data, in bits per second
 };
 extern Wippersnapper_V2 WsV2; ///< Wippersnapper V2 instance
 #endif                        // WS_GPS_HARDWARE_H