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DShotRMT
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...something

This commit is contained in:
Wastl Kraus 2025-08-08 14:43:26 +02:00
parent 395437dd30
commit 392d8c64d2
2 changed files with 15 additions and 14 deletions
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24
DShotRMT.cpp
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@ -141,7 +141,7 @@ uint16_t DShotRMT::getERPM()
return _last_erpm; return _last_erpm;
} }
// Decode the response // Decodes the response
uint16_t new_erpm = _decodeDShotFrame(_rx_symbols); uint16_t new_erpm = _decodeDShotFrame(_rx_symbols);
if (new_erpm != 0) if (new_erpm != 0)
{ {
@ -168,7 +168,7 @@ bool DShotRMT::_initTXChannel()
_tx_channel_config.mem_block_symbols = DSHOT_SYMBOLS_SIZE; _tx_channel_config.mem_block_symbols = DSHOT_SYMBOLS_SIZE;
_tx_channel_config.trans_queue_depth = TX_BUFFER_SIZE; _tx_channel_config.trans_queue_depth = TX_BUFFER_SIZE;
// // No loops, real time calculation for each frame
_transmit_config.loop_count = 0; _transmit_config.loop_count = 0;
// ...it's a trap // ...it's a trap
@ -215,14 +215,14 @@ bool DShotRMT::_initDShotEncoder()
// Use RMT to transmit a prepared DShot packet and returns it // Use RMT to transmit a prepared DShot packet and returns it
bool DShotRMT::_sendDShotFrame(const dshot_packet_t &packet) bool DShotRMT::_sendDShotFrame(const dshot_packet_t &packet)
{ {
// Exclude calculation from timing is more stable // Excludes calculation from timing is more stable
rmt_symbol_word_t tx_symbols[DSHOT_BITS_PER_FRAME]; rmt_symbol_word_t tx_symbols[DSHOT_BITS_PER_FRAME];
_encodeDShotFrame(packet, tx_symbols); _encodeDShotFrame(packet, tx_symbols);
// Checking timer signal // Checking timer signal
if (_timer_signal()) if (_timer_signal())
{ {
// Trigger RMT Transmit // Triggers RMT Transmit
rmt_transmit(_rmt_tx_channel, _dshot_encoder, tx_symbols, DSHOT_SYMBOLS_SIZE, &_transmit_config); rmt_transmit(_rmt_tx_channel, _dshot_encoder, tx_symbols, DSHOT_SYMBOLS_SIZE, &_transmit_config);
// Time Stamp // Time Stamp
@ -238,7 +238,7 @@ uint16_t DShotRMT::_calculateCRC(const dshot_packet_t &packet)
uint16_t data = (packet.throttle_value << 1) | packet.telemetric_request; uint16_t data = (packet.throttle_value << 1) | packet.telemetric_request;
uint16_t crc = (data ^ (data >> 4) ^ (data >> 8)) & 0b0000000000001111; uint16_t crc = (data ^ (data >> 4) ^ (data >> 8)) & 0b0000000000001111;
// Invert CRC for bidirectional DShot // Inverts CRC for bidirectional DShot
if (_is_bidirectional) if (_is_bidirectional)
{ {
crc = (~crc) & 0b0000000000001111; crc = (~crc) & 0b0000000000001111;
@ -260,7 +260,7 @@ dshot_packet_t DShotRMT::_buildDShotPacket(const uint16_t value)
// DShot Frame Container // DShot Frame Container
dshot_packet_t packet = {}; dshot_packet_t packet = {};
// Create DShot packet // Creates DShot packet
packet.throttle_value = value; packet.throttle_value = value;
packet.telemetric_request = 0; packet.telemetric_request = 0;
packet.checksum = _calculateCRC(packet); packet.checksum = _calculateCRC(packet);
@ -275,10 +275,10 @@ bool IRAM_ATTR DShotRMT::_encodeDShotFrame(const dshot_packet_t &packet, rmt_sym
// Parse actual packet into buffer // Parse actual packet into buffer
_current_packet = _parseDShotPacket(packet); _current_packet = _parseDShotPacket(packet);
// Convert the parsed dshot frame to rmt_tx data // Converts the parsed dshot frame to rmt_tx data
for (int i = 0; i < DSHOT_BITS_PER_FRAME; i++) for (int i = 0; i < DSHOT_BITS_PER_FRAME; i++)
{ {
// Encode RMT symbols bitwise (MSB first) - tricky // Encoded RMT symbols bitwise (MSB first) - tricky
bool bit = (_current_packet >> (DSHOT_BITS_PER_FRAME - 1 - i)) & 0b0000000000000001; bool bit = (_current_packet >> (DSHOT_BITS_PER_FRAME - 1 - i)) & 0b0000000000000001;
if (_is_bidirectional) if (_is_bidirectional)
{ {
@ -303,25 +303,25 @@ uint16_t DShotRMT::_decodeDShotFrame(const rmt_symbol_word_t *symbols)
{ {
uint16_t received_frame = 0; uint16_t received_frame = 0;
// Decode each symbol to reconstruct the frame // Decodes each symbol to reconstruct the frame
for (size_t i = 0; i < DSHOT_BITS_PER_FRAME; ++i) for (size_t i = 0; i < DSHOT_BITS_PER_FRAME; ++i)
{ {
bool bit = symbols[i].duration0 < symbols[i].duration1; bool bit = symbols[i].duration0 < symbols[i].duration1;
received_frame = (received_frame << 1) | bit; received_frame = (received_frame << 1) | bit;
} }
// Extract payload and CRC // Extracts payload and CRC
uint16_t data = received_frame >> 4; uint16_t data = received_frame >> 4;
uint16_t received_crc = received_frame & 0b0000000000001111; uint16_t received_crc = received_frame & 0b0000000000001111;
// Calculate CRC for received frame // Calculates CRC for received frame
uint16_t calculated_crc = (data ^ (data >> 4) ^ (data >> 8)) & 0b0000000000001111; uint16_t calculated_crc = (data ^ (data >> 4) ^ (data >> 8)) & 0b0000000000001111;
if (_is_bidirectional) if (_is_bidirectional)
{ {
calculated_crc = (~calculated_crc) & 0b0000000000001111; calculated_crc = (~calculated_crc) & 0b0000000000001111;
} }
// Compare CRC // Compares CRC
if (received_crc != calculated_crc) if (received_crc != calculated_crc)
{ {
Serial.println(DSHOT_MSG_04); Serial.println(DSHOT_MSG_04);

5
DShotRMT.h
View File

@ -122,7 +122,7 @@ private:
dshot_packet_t _packet; dshot_packet_t _packet;
unsigned long _last_transmission_time; unsigned long _last_transmission_time;
// // ---Helpers ---
bool _initTXChannel(); bool _initTXChannel();
bool _initRXChannel(); bool _initRXChannel();
bool _initDShotEncoder(); bool _initDShotEncoder();
@ -134,10 +134,11 @@ private:
bool IRAM_ATTR _encodeDShotFrame(const dshot_packet_t &packet, rmt_symbol_word_t *symbols); bool IRAM_ATTR _encodeDShotFrame(const dshot_packet_t &packet, rmt_symbol_word_t *symbols);
uint16_t _decodeDShotFrame(const rmt_symbol_word_t *symbols); uint16_t _decodeDShotFrame(const rmt_symbol_word_t *symbols);
// --- Simple Timer ---
bool _timer_signal(); bool _timer_signal();
bool _timer_reset(); bool _timer_reset();
// Error Handling // --- Error Handling ---
static constexpr bool DSHOT_OK = 0; static constexpr bool DSHOT_OK = 0;
static constexpr bool DSHOT_ERROR = 1; static constexpr bool DSHOT_ERROR = 1;
static constexpr char *DSHOT_MSG_01 = "Failed to initialize TX channel!"; static constexpr char *DSHOT_MSG_01 = "Failed to initialize TX channel!";