Switch USB serial output between status & dbg msgs to GNSS data

Author: LeeLeahy2

Firmware/RTK_Everywhere/Tasks.ino

@@ -56,12 +56,13 @@ enum RingBufferConsumers
     RBC_TCP_SERVER,
     RBC_SD_CARD,
     RBC_UDP_SERVER,
+    RBC_USB_SERIAL,
     // Insert new consumers here
     RBC_MAX
 };
 
 const char *const ringBufferConsumer[] = {
-    "Bluetooth", "TCP Client", "TCP Server", "SD Card", "UDP Server",
+    "Bluetooth", "TCP Client", "TCP Server", "SD Card", "UDP Server", "USB Serial",
 };
 
 const int ringBufferConsumerEntries = sizeof(ringBufferConsumer) / sizeof(ringBufferConsumer[0]);
@@ -101,6 +102,7 @@ unsigned long lastGnssSend; // Timestamp of the last time we sent RTCM to GNSS
 // Ring buffer tails
 static RING_BUFFER_OFFSET btRingBufferTail; // BT Tail advances as it is sent over BT
 static RING_BUFFER_OFFSET sdRingBufferTail; // SD Tail advances as it is recorded to SD
+static RING_BUFFER_OFFSET usbRingBufferTail; // USB Tail advances as it is sent over USB serial
 
 // Ring buffer offsets
 static uint16_t rbOffsetHead;
@@ -898,6 +900,58 @@ void handleGnssDataTask(void *e)
             }
         }
 
+        //----------------------------------------------------------------------
+        // Send data over USB serial
+        //----------------------------------------------------------------------
+
+        startMillis = millis();
+
+        // Determine USB serial connection state
+        if (!forwardGnssDataToUsbSerial)
+            // Discard the data
+            usbRingBufferTail = dataHead;
+        else
+        {
+            // Determine the amount of USB serial data in the buffer
+            bytesToSend = dataHead - usbRingBufferTail;
+            if (bytesToSend < 0)
+                bytesToSend += settings.gnssHandlerBufferSize;
+            if (bytesToSend > 0)
+            {
+                // Reduce bytes to send if we have more to send then the end of
+                // the buffer, we'll wrap next loop
+                if ((usbRingBufferTail + bytesToSend) > settings.gnssHandlerBufferSize)
+                    bytesToSend = settings.gnssHandlerBufferSize - usbRingBufferTail;
+
+                // Send data over USB serial to the PC
+                bytesToSend = systemWriteGnssDataToUsbSerial(&ringBuffer[usbRingBufferTail], bytesToSend);
+
+                // Account for the data that was sent
+                if (bytesToSend > 0)
+                {
+                    // Account for the sent or dropped data
+                    usbRingBufferTail += bytesToSend;
+                    if (usbRingBufferTail >= settings.gnssHandlerBufferSize)
+                        usbRingBufferTail -= settings.gnssHandlerBufferSize;
+
+                    // Remember the maximum transfer time
+                    deltaMillis = millis() - startMillis;
+                    if (maxMillis[RBC_USB_SERIAL] < deltaMillis)
+                        maxMillis[RBC_USB_SERIAL] = deltaMillis;
+                }
+
+                // Determine the amount of data that remains in the buffer
+                bytesToSend = dataHead - usbRingBufferTail;
+                if (bytesToSend < 0)
+                    bytesToSend += settings.gnssHandlerBufferSize;
+                if (usedSpace < bytesToSend)
+                {
+                    usedSpace = bytesToSend;
+                    slowConsumer = "USB Serial";
+                }
+            }
+        }
+
         //----------------------------------------------------------------------
         // Send data to the network clients
         //----------------------------------------------------------------------

Firmware/RTK_Everywhere/support.ino

@@ -19,17 +19,28 @@ int systemRead()
 // Output a buffer of the specified length to the serial port
 void systemWrite(const uint8_t *buffer, uint16_t length)
 {
-    if (printEndpoint == PRINT_ENDPOINT_ALL)
-    {
-        Serial.write(buffer, length);
-        bluetoothWrite(buffer, length);
-    }
-    else if (printEndpoint == PRINT_ENDPOINT_BLUETOOTH)
+    // Output data to bluetooth if necessary
+    if ((printEndpoint == PRINT_ENDPOINT_ALL)
+        || (printEndpoint == PRINT_ENDPOINT_BLUETOOTH))
         bluetoothWrite(buffer, length);
-    else
+
+    // Output data to USB serial if necessary
+    if ((printEndpoint != PRINT_ENDPOINT_BLUETOOTH)
+        && (!forwardGnssDataToUsbSerial))
         Serial.write(buffer, length);
 }
 
+// Forward GNSS data to the USB serial port
+size_t systemWriteGnssDataToUsbSerial(const uint8_t *buffer, uint16_t length)
+{
+    // Determine if status and debug messages are being output to USB serial
+    if (!forwardGnssDataToUsbSerial)
+        return length;
+
+    // Output GNSS data to USB serial
+    return Serial.write(buffer, length);
+}
+
 // Ensure all serial output has been transmitted, FIFOs are empty
 void systemFlush()
 {