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LeeLeahy2LeeLeahy2
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Added ring buffer to F9PSerialReadTask
Use a ring buffer to eliminate loss of data. The 6 KB ring buffer can hold about 2 seconds of data. This should be able to dump the entire buffer to Bluetooth in under a second and easily write the entire buffer to the microSD card within that time. Compiling with the Core Debug Level set to Debug and entering Serial Config to list the microSD card files should generate the warning about the SD card semaphore not being released. There may need to be a large number (~100) of files on the microSD card. I have left the Bluetooth congestion error and the sdCardSemaphore error in the serial output (customer visible) so that we may get customer feedback if these errors ever occur.
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2 files changed

+162
-20
lines changed

2 files changed

+162
-20
lines changed

‎Firmware/RTK_Surveyor/RTK_Surveyor.ino‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -233,7 +233,6 @@ char platformPrefix[40] = "Surveyor"; //Sets the prefix for broadcast names
233233
HardwareSerial serialGNSS(2); //TX on 17, RX on 16
234234

235235
#define SERIAL_SIZE_RX (1024 * 6) //Should match buffer size in BluetoothSerial.cpp. Reduced from 16384 to make room for WiFi/NTRIP server capabilities
236-
uint8_t rBuffer[SERIAL_SIZE_RX]; //Buffer for reading from F9P to SPP
237236
TaskHandle_t F9PSerialReadTaskHandle = NULL; //Store handles so that we can kill them if user goes into WiFi NTRIP Server mode
238237
const uint8_t F9PSerialReadTaskPriority = 1; //3 being the highest, and 0 being the lowest
239238

‎Firmware/RTK_Surveyor/Tasks.ino‎

Lines changed: 162 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -33,59 +33,202 @@ void F9PSerialWriteTask(void *e)
3333
//Task for reading data from the GNSS receiver.
3434
void F9PSerialReadTask(void *e)
3535
{
36+
int btConnected; //Is the RTK in a state to send Bluetooth data?
37+
int btData; //Amount of buffered Bluetooth data
38+
int length;
39+
static uint8_t rBuffer[SERIAL_SIZE_RX]; //Buffer for reading from F9P to SPP
40+
static uint16_t rBufferBtOffset; //Removal offset for Bluetooth
41+
static uint16_t rBufferFillOffset; //Fill offset for serial data
42+
static uint16_t rBufferSdOffset; //Removal offset for microSD card logging
43+
int s;
44+
int sdData; //Amount of buffered microSD card logging data
45+
3646
while (true)
3747
{
3848
while (serialGNSS.available())
3949
{
40-
int s = serialGNSS.readBytes(rBuffer, sizeof(rBuffer));
50+
if (settings.enableTaskReports == true)
51+
Serial.printf("SerialReadTask High watermark: %d\n\r", uxTaskGetStackHighWaterMark(NULL));
4152

42-
//If we are actively survey-in then do not pass NMEA data from ZED to phone
43-
if (systemState == STATE_BASE_TEMP_SETTLE || systemState == STATE_BASE_TEMP_SURVEY_STARTED)
53+
//----------------------------------------------------------------------
54+
//At approximately 3.3K characters/second, a 6K byte buffer should hold
55+
//approximately 2 seconds worth of data. Bluetooth congestion or conflicts
56+
//with the SD card semaphore should clear within this time. At 57600 baud
57+
//the Bluetooth UART is able to send 7200 characters a second. With a 10
58+
//mSec delay this rouitne runs approximately 100 times per second providing
59+
//multiple chances to empty the buffer.
60+
//
61+
//Ring buffer empty when (rBufferFillOffset == rBufferBtOffset) and
62+
//(rBufferFillOffset == rBufferSdOffset)
63+
//
64+
// +---------+
65+
// | |
66+
// | |
67+
// | |
68+
// | |
69+
// +---------+ <-- rBufferFillOffset, rBufferBtOffset, rBufferSdOffset
70+
//
71+
//Ring buffer contains data when (rBufferFillOffset != rBufferBtOffset) or
72+
//(rBufferFillOffset != rBufferSdOffset)
73+
//
74+
// +---------+
75+
// | |
76+
// | |
77+
// | yyyyyyy | <-- rBufferFillOffset
78+
// | xxxxxxx | <-- rBufferBtOffset (1 byte in buffer)
79+
// +---------+ <-- rBufferSdOffset (2 bytes in buffer)
80+
//
81+
// +---------+
82+
// | yyyyyyy | <-- rBufferBtOffset (1 byte in buffer)
83+
// | xxxxxxx | <-- rBufferSdOffset (2 bytes in buffer)
84+
// | |
85+
// | |
86+
// +---------+ <-- rBufferFillOffset
87+
//
88+
//Maximum ring buffer fill is sizeof(rBuffer) - 1
89+
//----------------------------------------------------------------------
90+
91+
//Determine the amount of Bluetooth data in the buffer
92+
length = sizeof(rBuffer);
93+
btData = 0;
94+
btConnected = (bluetoothGetState() == BT_CONNECTED)
95+
&& (systemState != STATE_BASE_TEMP_SETTLE)
96+
&& (systemState != STATE_BASE_TEMP_SURVEY_STARTED);
97+
if (btConnected)
4498
{
45-
//Do nothing
46-
taskYIELD();
99+
btData = rBufferFillOffset - rBufferBtOffset;
100+
if (btData < 0)
101+
btData += sizeof(rBuffer);
102+
length = sizeof(rBuffer) - btData;
47103
}
48-
else if (bluetoothGetState() == BT_CONNECTED)
104+
105+
//Determine the amount of microSD card logging data in the buffer
106+
sdData = 0;
107+
if (online.logging)
108+
{
109+
sdData = rBufferFillOffset - rBufferSdOffset;
110+
if (sdData < 0)
111+
sdData += sizeof(rBuffer);
112+
if (length > (sizeof(rBuffer) - sdData))
113+
length = sizeof(rBuffer) - sdData;
114+
}
115+
116+
//Determine the free bytes in the buffer
117+
//Don't fill the last byte to prevent buffer overflow
118+
if (length)
119+
length -= 1;
120+
121+
//Fill the buffer to the end and then start at the beginning
122+
if ((rBufferFillOffset + length) > sizeof(rBuffer))
123+
length = sizeof(rBuffer) - rBufferFillOffset;
124+
125+
//Read more data from the GNSS into the buffer
126+
s = 0;
127+
if (length)
128+
s = serialGNSS.readBytes(rBuffer, length);
129+
130+
//Account for the byte read
131+
if (s > 0)
132+
{
133+
//Set the next fill offset
134+
rBufferFillOffset += s;
135+
if (rBufferFillOffset >= sizeof(rBuffer))
136+
rBufferFillOffset -= sizeof(rBuffer);
137+
138+
//Account for the new data
139+
if (btConnected)
140+
btData += s;
141+
if (online.logging)
142+
sdData += s;
143+
}
144+
145+
//----------------------------------------------------------------------
146+
//Send data over Bluetooth
147+
//----------------------------------------------------------------------
148+
149+
//If we are actively survey-in then do not pass NMEA data from ZED to phone
150+
if (!btData)
151+
//Discard the data
152+
rBufferBtOffset = rBufferFillOffset;
153+
else
49154
{
155+
//Fill the buffer to the end and then start at the beginning
156+
length = btData;
157+
if ((rBufferBtOffset + length) > sizeof(rBuffer))
158+
length = sizeof(rBuffer) - rBufferBtOffset;
159+
50160
if ((bluetoothIsCongested() == false) || (settings.throttleDuringSPPCongestion == false))
51-
{
52161
//Push new data to BT SPP if not congested or not throttling
53-
bluetoothWriteBytes(rBuffer, s);
54-
}
162+
length = bluetoothWriteBytes(&rBuffer[rBufferBtOffset], length);
55163
else
56164
{
57165
//Don't push data to BT SPP if there is congestion to prevent heap hits.
58-
log_d("Dropped SPP Bytes: %d", s);
166+
if (btData < (sizeof(rBuffer) - 1))
167+
length = 0;
168+
else
169+
Serial.printf("ERROR - Congestion, dropped %d bytes: GNSS --> Bluetooth\r\n", length);
59170
}
171+
172+
//Account for the sent data or dropped
173+
//Set the next removal offset
174+
rBufferBtOffset += length;
175+
if (rBufferBtOffset >= sizeof(rBuffer))
176+
rBufferBtOffset -= sizeof(rBuffer);
60177
}
61178

62-
if (settings.enableTaskReports == true)
63-
Serial.printf("SerialReadTask High watermark: %d\n\r", uxTaskGetStackHighWaterMark(NULL));
179+
//----------------------------------------------------------------------
180+
//Log data to the SD card
181+
//----------------------------------------------------------------------
64182

65183
//If user wants to log, record to SD
66-
if (online.logging == true)
184+
if (!online.logging)
185+
//Discard the data
186+
rBufferSdOffset = rBufferFillOffset;
187+
else
67188
{
68189
//Check if we are inside the max time window for logging
69190
if ((systemTime_minutes - startLogTime_minutes) < settings.maxLogTime_minutes)
70191
{
71-
//Attempt to write to file system. This avoids collisions with file writing from other functions like recordSystemSettingsToFile()
192+
//Attempt to gain access to the SD card, avoids collisions with file
193+
//writing from other functions like recordSystemSettingsToFile()
72194
if (xSemaphoreTake(sdCardSemaphore, fatSemaphore_shortWait_ms) == pdPASS)
73195
{
74-
ubxFile->write(rBuffer, s);
196+
//Fill the buffer to the end and then start at the beginning
197+
length = sdData;
198+
if ((rBufferSdOffset + length) > sizeof(rBuffer))
199+
length = sizeof(rBuffer) - rBufferSdOffset;
75200

201+
//Write the data to the file
202+
length = ubxFile->write(rBuffer, length);
76203
xSemaphoreGive(sdCardSemaphore);
204+
205+
//Account for the sent data or dropped
206+
rBufferSdOffset += length;
207+
if (rBufferSdOffset >= sizeof(rBuffer))
208+
rBufferSdOffset -= sizeof(rBuffer);
77209
} //End sdCardSemaphore
78210
else
79211
{
80-
//Error causing dropped bytes in the log file
81-
Serial.printf("sdCardSemaphore failed to yield, Tasks.ino line %d\r\n", __LINE__);
212+
//Retry the semaphore a little later if possible
213+
if (sdData == (sizeof(rBuffer) - 1))
214+
{
215+
//Error - no more room in the buffer, drop a buffer's worth of data
216+
rBufferSdOffset = rBufferFillOffset;
217+
log_e("ERROR - sdCardSemaphore failed to yield, Tasks.ino line %d\r\n", __LINE__);
218+
Serial.printf("ERROR - Dropped %d bytes: GNSS --> log file\r\n", sdData);
219+
}
220+
else
221+
log_w("WARNING - sdCardSemaphore failed to yield, Tasks.ino line %d\r\n", __LINE__);
82222
}
83223
} //End maxLogTime
84224
} //End logging
85225
} //End Serial.available()
86226

87-
delay(1); //Poor man's way of feeding WDT. Required to prevent Priority 1 tasks from causing WDT reset
88-
taskYIELD();
227+
//----------------------------------------------------------------------
228+
//Let other tasks run, prevent watch dog timer (WDT) resets
229+
//----------------------------------------------------------------------
230+
231+
delay(10);
89232
}
90233
}
91234

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