From 06ee4d00a087f0b51526d5388ef977693f2ad7bc Mon Sep 17 00:00:00 2001 From: Wastl Kraus Date: Wed, 23 Jul 2025 00:12:08 +0200 Subject: [PATCH] ...use dshot_packet structure --- DShotRMT.cpp | 74 ++++++++++++++++++++++------------------------------ DShotRMT.h | 21 +++++++-------- 2 files changed, 41 insertions(+), 54 deletions(-) diff --git a/DShotRMT.cpp b/DShotRMT.cpp index 0d00a66..5b7056a 100644 --- a/DShotRMT.cpp +++ b/DShotRMT.cpp @@ -41,6 +41,8 @@ void DShotRMT::begin() _receive_config.signal_range_min_ns = 300; _receive_config.signal_range_max_ns = 5000; + + _dshot_packet.telemetric_request = _isBidirectional; } // Configure TX RMT Channel @@ -82,17 +84,15 @@ void DShotRMT::begin() // Encodes and transmits a valid DShot throttle value (48 - 2047) void DShotRMT::setThrottle(uint16_t throttle) { - // Clamp input range and mask to 11 bits - throttle = constrain(throttle, DSHOT_THROTTLE_MIN, DSHOT_THROTTLE_MAX) & 0x7FF; + // Clamp input range for packet + _dshot_packet.throttle_value = constrain(throttle, DSHOT_THROTTLE_MIN, DSHOT_THROTTLE_MAX) & 0b0000011111111111; - _lastThrottle = throttle; - - // Convert throttle value to DShot packet format - _tx_packet = assambleDShotPaket(_lastThrottle); + // Calculate CRC for every throttle value + calculateCRC(&_dshot_packet); // Encode RMT symbols size_t count = 0; - encodeDShotTX(_tx_packet, _tx_symbols, count); + encodeDShotTX(&_dshot_packet, _tx_symbols, count); // Transmit the packet if (rmt_transmit(_rmt_tx_channel, _dshot_encoder, _tx_symbols, count * sizeof(rmt_symbol_word_t), &_transmit_config) != 0) @@ -111,13 +111,17 @@ uint32_t DShotRMT::getERPM() if (_isBidirectional) { if (_rmt_rx_channel == nullptr) + { Serial.println("No bidirectional DShot support."); return _last_erpm; + } // Try to receive a new frame if (!rmt_receive(_rmt_rx_channel, _rx_symbols, sizeof(_rx_symbols), &_receive_config)) + { Serial.println("No valid DShot frame received"); return _last_erpm; + } _last_erpm = decodeDShotRX(_rx_symbols, DSHOT_BITS_PER_FRAME); return _last_erpm; @@ -138,45 +142,35 @@ uint32_t DShotRMT::getMotorRPM(uint8_t magnet_count) } // Calculates CRC for DShot packet -uint16_t DShotRMT::calculateCRC(uint16_t dshot_packet) +void DShotRMT::calculateCRC(dshot_packet_t *dshot_packet) { - uint16_t packet = (dshot_packet << 1) | (_isBidirectional ? 1 : 0); + uint16_t packet = (dshot_packet->throttle_value << 1) | (dshot_packet->telemetric_request); // Reset CRC container - _packet_crc = DSHOT_NULL_PACKET; + dshot_packet->checksum = DSHOT_NULL_PACKET; // CRC calculation for DShot (4 bits) - _packet_crc = ((packet ^ (packet >> 4) ^ (packet >> 8)) & 0xF); + dshot_packet->checksum = ((packet ^ (packet >> 4) ^ (packet >> 8)) & 0b0000000000001111); // CRC is inverted for bidirectional DShot - if (_isBidirectional) - _packet_crc = (~_packet_crc) & 0xF; - - return _packet_crc; + if (dshot_packet->telemetric_request) + dshot_packet->checksum = (~dshot_packet->checksum) & 0b0000000000001111; } // Assembles DShot packet (11 bit throttle + 1 bit telemetry request + 4 bit CRC) -uint16_t DShotRMT::assambleDShotPaket(uint16_t value) +uint16_t DShotRMT::parseDShotPacket(const dshot_packet_t *dshot_packet) const { - uint16_t throttle = value & 0x7FF; - - // Reset packet container - _tx_packet = DSHOT_NULL_PACKET; - - // Assemble raw DShot packet and add checksum - _packet_crc = calculateCRC(throttle); - - _tx_packet = (throttle << 1) | (_isBidirectional ? 1 : 0); - _tx_packet = (_tx_packet << 4) | _packet_crc; - - return _tx_packet; + uint16_t parsed_packet = ((dshot_packet->throttle_value << 1) | (dshot_packet->telemetric_request)) & 0b0000111111111111; + return ((parsed_packet << 4) | (dshot_packet->checksum)) & 0b1111111111111111; } // Converts a 16-bit packet into a valid DShot frame for RMT -void DShotRMT::encodeDShotTX(uint16_t dshot_packet, rmt_symbol_word_t *symbols, size_t &count) +void DShotRMT::encodeDShotTX(dshot_packet_t *dshot_packet, rmt_symbol_word_t *symbols, size_t &count) { count = 0; + uint16_t frame_bits = parseDShotPacket(dshot_packet); + uint32_t ticks_per_bit = 0; uint32_t ticks_zero_high = 0; uint32_t ticks_one_high = 0; @@ -205,20 +199,16 @@ void DShotRMT::encodeDShotTX(uint16_t dshot_packet, rmt_symbol_word_t *symbols, ticks_one_high = 6; break; case DSHOT_OFF: - default: - ticks_per_bit = 0; - ticks_zero_high = 0; - ticks_one_high = 0; - break; + return; } uint32_t ticks_zero_low = ticks_per_bit - ticks_zero_high; uint32_t ticks_one_low = ticks_per_bit - ticks_one_high; - // Fill the 16 DShot bits array with selected timings + // Convert the parsed dshot frame to rmt_tx data for (int i = 15; i >= 0; i--) { - bool bit = (dshot_packet >> i) & 0x1; + bool bit = (frame_bits >> i) & 0x1; if (_isBidirectional) { symbols[count].level0 = 0; @@ -251,12 +241,12 @@ uint16_t DShotRMT::decodeDShotRX(const rmt_symbol_word_t *symbols, uint32_t coun // Extract CRC and payload uint16_t payload = received_frame >> 4; - uint8_t crc_received = received_frame & 0xF; + uint8_t crc_received = received_frame & 0b0000000000001111; // Calculate CRC for received frame - uint8_t crc_calculated = (payload ^ (payload >> 4) ^ (payload >> 8)) & 0xF; + uint8_t crc_calculated = (payload ^ (payload >> 4) ^ (payload >> 8)) & 0b0000000000001111; if (_isBidirectional) - crc_calculated = (~crc_calculated) & 0xF; + crc_calculated = (~crc_calculated) & 0b0000000000001111; // Check CRC if (crc_received != crc_calculated) @@ -265,8 +255,6 @@ uint16_t DShotRMT::decodeDShotRX(const rmt_symbol_word_t *symbols, uint32_t coun return _last_erpm; } - // Remove telemetry bit, keep raw value - uint16_t raw = payload >> 1; - - return _last_erpm = raw; + // Remove telemetry bit + return _last_erpm = payload >> 1; } diff --git a/DShotRMT.h b/DShotRMT.h index a512525..e00d1e4 100644 --- a/DShotRMT.h +++ b/DShotRMT.h @@ -32,15 +32,15 @@ static constexpr size_t TX_BUFFER_SIZE = DSHOT_BITS_PER_FRAME; static constexpr size_t RX_BUFFER_SIZE = 32; // Padding for RX decoding // DShot Packet structure -typedef struct +typedef struct dshot_packet_s { uint16_t throttle_value : 11; bool telemetric_request : 1; - uint16_t checksum : 4; + uint8_t checksum : 4; } dshot_packet_t; // --- DShot Mode Selection --- -typedef enum +typedef enum dshot_mode_s { DSHOT_OFF, DSHOT150, @@ -72,19 +72,20 @@ public: uint8_t getPauseDuration() const { return _pauseDuration; } void setPauseDuration(uint8_t pauseDuration) { _pauseDuration = pauseDuration; } -private: +protected: // Calculates the checksum for a DShot packet - uint16_t calculateCRC(uint16_t dshot_packet); + void calculateCRC(dshot_packet_t *dshot_packet); - // Assembles DShot packet (11 bit throttle + 1 bit telemetry request + 4 bit CRC) - uint16_t assambleDShotPaket(uint16_t value); + // Parses the DShot packet (11 bit throttle + 1 bit telemetry request + 4 bit CRC) + uint16_t parseDShotPacket(const dshot_packet_t *dshot_packet) const; // Converts a 16-bit DShot packet into RMT symbols - void encodeDShotTX(uint16_t dshot_packet, rmt_symbol_word_t *symbols, size_t &count); + void encodeDShotTX(dshot_packet_t *dshot_packet, rmt_symbol_word_t *symbols, size_t &count); // Decodes the ESC answer uint16_t decodeDShotRX(const rmt_symbol_word_t *symbols, uint32_t count); +private: // --- Configuration Parameters --- gpio_num_t _gpio; dshot_mode_t _mode; @@ -92,10 +93,8 @@ private: uint8_t _pauseDuration; // --- DShot Packets Container --- - uint16_t _lastThrottle = DSHOT_NULL_PACKET; uint16_t _rx_packet = DSHOT_NULL_PACKET; - uint16_t _tx_packet = DSHOT_NULL_PACKET; - uint8_t _packet_crc = 0; + dshot_packet_t _dshot_packet = {}; // --- RMT Channel Handles --- rmt_channel_handle_t _rmt_rx_channel = nullptr;