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Update for latest M17 specification.

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This commit is contained in:
Jonathan Naylor
2020-11-26 10:03:54 +00:00
parent 54f4dcabf0
commit 6d0335b357
6 changed files with 140 additions and 21 deletions
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M17RX.cpp
+75 -10
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@@ -55,6 +55,7 @@ m_maxSyncPtr(NOENDPTR),
m_maxCorr(0),
m_lostCount(0U),
m_countdown(0U),
m_nextState(M17RXS_NONE),
m_centre(),
m_centreVal(0),
m_threshold(),
@@ -81,6 +82,7 @@ void CM17RX::reset()
m_thresholdVal = 0;
m_lostCount = 0U;
m_countdown = 0U;
m_nextState = M17RXS_NONE;
m_rssiAccum = 0U;
m_rssiCount = 0U;
}
@@ -100,6 +102,9 @@ void CM17RX::samples(const q15_t* samples, uint16_t* rssi, uint8_t length)
m_buffer[m_dataPtr] = sample;
switch (m_state) {
case M17RXS_HEADER:
processHeader(sample);
break;
case M17RXS_DATA:
processData(sample);
break;
@@ -120,8 +125,10 @@ void CM17RX::samples(const q15_t* samples, uint16_t* rssi, uint8_t length)
void CM17RX::processNone(q15_t sample)
{
bool ret = correlateSync();
if (ret) {
bool ret1 = correlateSync(M17_HEADER_SYNC_SYMBOLS, M17_HEADER_SYNC_SYMBOLS_VALUES, M17_HEADER_SYNC_BYTES);
bool ret2 = correlateSync(M17_DATA_SYNC_SYMBOLS, M17_DATA_SYNC_SYMBOLS_VALUES, M17_DATA_SYNC_BYTES);
if (ret1 || ret2) {
// On the first sync, start the countdown to the state change
if (m_countdown == 0U) {
m_rssiAccum = 0U;
@@ -133,6 +140,8 @@ void CM17RX::processNone(q15_t sample)
m_averagePtr = NOAVEPTR;
m_countdown = 5U;
m_nextState = ret1 ? M17RXS_HEADER : M17RXS_DATA;
}
}
@@ -148,19 +157,53 @@ void CM17RX::processNone(q15_t sample)
if (m_maxSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
m_maxSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
m_state = M17RXS_DATA;
m_state = m_nextState;
m_countdown = 0U;
}
}
void CM17RX::processHeader(q15_t sample)
{
if (m_minSyncPtr < m_maxSyncPtr) {
if (m_dataPtr >= m_minSyncPtr && m_dataPtr <= m_maxSyncPtr)
correlateSync(M17_HEADER_SYNC_SYMBOLS, M17_HEADER_SYNC_SYMBOLS_VALUES, M17_HEADER_SYNC_BYTES);
} else {
if (m_dataPtr >= m_minSyncPtr || m_dataPtr <= m_maxSyncPtr)
correlateSync(M17_HEADER_SYNC_SYMBOLS, M17_HEADER_SYNC_SYMBOLS_VALUES, M17_HEADER_SYNC_BYTES);
}
if (m_dataPtr == m_endPtr) {
m_minSyncPtr = m_syncPtr + M17_FRAME_LENGTH_SAMPLES - 1U;
if (m_minSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
m_minSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
m_maxSyncPtr = m_syncPtr + 1U;
if (m_maxSyncPtr >= M17_FRAME_LENGTH_SAMPLES)
m_maxSyncPtr -= M17_FRAME_LENGTH_SAMPLES;
calculateLevels(m_startPtr, M17_FRAME_LENGTH_SYMBOLS);
DEBUG4("M17RX: header sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[M17_FRAME_LENGTH_BYTES + 3U];
samplesToBits(m_startPtr, M17_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
m_lostCount--;
frame[0U] = 0x01U;
writeRSSIHeader(frame);
m_state = M17RXS_DATA;
m_maxCorr = 0;
}
}
void CM17RX::processData(q15_t sample)
{
if (m_minSyncPtr < m_maxSyncPtr) {
if (m_dataPtr >= m_minSyncPtr && m_dataPtr <= m_maxSyncPtr)
correlateSync();
correlateSync(M17_DATA_SYNC_SYMBOLS, M17_DATA_SYNC_SYMBOLS_VALUES, M17_DATA_SYNC_BYTES);
} else {
if (m_dataPtr >= m_minSyncPtr || m_dataPtr <= m_maxSyncPtr)
correlateSync();
correlateSync(M17_DATA_SYNC_SYMBOLS, M17_DATA_SYNC_SYMBOLS_VALUES, M17_DATA_SYNC_BYTES);
}
if (m_dataPtr == m_endPtr) {
@@ -177,7 +220,7 @@ void CM17RX::processData(q15_t sample)
calculateLevels(m_startPtr, M17_FRAME_LENGTH_SYMBOLS);
DEBUG4("M17RX: sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
DEBUG4("M17RX: data sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
uint8_t frame[M17_FRAME_LENGTH_BYTES + 3U];
samplesToBits(m_startPtr, M17_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
@@ -196,6 +239,7 @@ void CM17RX::processData(q15_t sample)
m_endPtr = NOENDPTR;
m_averagePtr = NOAVEPTR;
m_countdown = 0U;
m_nextState = M17RXS_NONE;
m_maxCorr = 0;
} else {
frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
@@ -205,9 +249,9 @@ void CM17RX::processData(q15_t sample)
}
}
bool CM17RX::correlateSync()
bool CM17RX::correlateSync(uint8_t syncSymbols, const int8_t* syncSymbolValues, const uint8_t* syncBytes)
{
if (countBits8(m_bitBuffer[m_bitPtr] ^ M17_SYNC_SYMBOLS) <= MAX_SYNC_SYMBOLS_ERRS) {
if (countBits8(m_bitBuffer[m_bitPtr] ^ syncSymbols) <= MAX_SYNC_SYMBOLS_ERRS) {
uint16_t ptr = m_dataPtr + M17_FRAME_LENGTH_SAMPLES - M17_SYNC_LENGTH_SAMPLES + M17_RADIO_SYMBOL_LENGTH;
if (ptr >= M17_FRAME_LENGTH_SAMPLES)
ptr -= M17_FRAME_LENGTH_SAMPLES;
@@ -224,7 +268,7 @@ bool CM17RX::correlateSync()
if (val < min)
min = val;
switch (M17_SYNC_SYMBOLS_VALUES[i]) {
switch (syncSymbolValues[i]) {
case +3:
corr -= (val + val + val);
break;
@@ -267,7 +311,7 @@ bool CM17RX::correlateSync()
uint8_t errs = 0U;
for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++)
errs += countBits8(sync[i] ^ M17_SYNC_BYTES[i]);
errs += countBits8(sync[i] ^ syncBytes[i]);
if (errs <= maxErrs) {
m_maxCorr = corr;
@@ -385,6 +429,27 @@ void CM17RX::samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint
}
}
void CM17RX::writeRSSIHeader(uint8_t* data)
{
#if defined(SEND_RSSI_DATA)
if (m_rssiCount > 0U) {
uint16_t rssi = m_rssiAccum / m_rssiCount;
data[121U] = (rssi >> 8) & 0xFFU;
data[122U] = (rssi >> 0) & 0xFFU;
serial.writeM17Header(data, M17_FRAME_LENGTH_BYTES + 3U);
} else {
serial.writeM17Header(data, M17_FRAME_LENGTH_BYTES + 1U);
}
#else
serial.writeM17Header(data, M17_FRAME_LENGTH_BYTES + 1U);
#endif
m_rssiAccum = 0U;
m_rssiCount = 0U;
}
void CM17RX::writeRSSIData(uint8_t* data)
{
#if defined(SEND_RSSI_DATA)