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DShotRMT
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...use some modern features 

...using "auto" for some variables is good, new style
This commit is contained in:
Wastl Kraus 2025-08-17 23:00:43 +02:00
parent c37a66d5a5
commit 2f5948f3be
3 changed files with 85 additions and 78 deletions
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77
DShotRMT.cpp
View File

@ -18,7 +18,7 @@ constexpr dshot_timing_t DSHOT_TIMINGS[] = {
{16, 8, 6, 2, 3, 5} // DSHOT1200 {16, 8, 6, 2, 3, 5} // DSHOT1200
}; };
// --- DShot Config --- // --- DShot Config Constructor ---
DShotRMT::DShotRMT(gpio_num_t gpio, dshot_mode_t mode, bool is_bidirectional): DShotRMT::DShotRMT(gpio_num_t gpio, dshot_mode_t mode, bool is_bidirectional):
_gpio(gpio), _gpio(gpio),
_mode(mode), _mode(mode),
@ -32,21 +32,24 @@ DShotRMT::DShotRMT(gpio_num_t gpio, dshot_mode_t mode, bool is_bidirectional):
_packet{0}, _packet{0},
_last_transmission_time(0) _last_transmission_time(0)
{ {
// Double up frame time for bidirectional mode // Calculates frame time and adds switch/pause time
_frame_timer_us = _timing_config.frame_length_us + DSHOT_SWITCH_TIME;
// Doubles up frame time for bidirectional mode
if (_is_bidirectional) if (_is_bidirectional)
{ {
_frame_timer_us = (_timing_config.frame_length_us << 1) + DSHOT_SWITCH_TIME; // DSHOT_SWITCH_TIME also needed two times
_frame_timer_us = (_frame_timer_us << 1);
} }
// Calculate frame time including switch time
_frame_timer_us = _timing_config.frame_length_us + DSHOT_SWITCH_TIME;
} }
// Easy Constructor // Easy Constructor
DShotRMT::DShotRMT(uint16_t pin_nr, dshot_mode_t mode, bool is_bidirectional): DShotRMT::DShotRMT(uint16_t pin_nr, dshot_mode_t mode, bool is_bidirectional):
DShotRMT((gpio_num_t)pin_nr, DShotRMT(
mode, (gpio_num_t)pin_nr,
is_bidirectional) mode,
is_bidirectional
)
{ {
// ...just to accept pin numbers and GPIO_NUMs // ...just to accept pin numbers and GPIO_NUMs
} }
@ -54,24 +57,24 @@ DShotRMT::DShotRMT(uint16_t pin_nr, dshot_mode_t mode, bool is_bidirectional):
// Setup and configure DShotRMT // Setup and configure DShotRMT
bool DShotRMT::begin() bool DShotRMT::begin()
{ {
// Init TX Channel // Inits TX Channel
if (!_initTXChannel()) if (!_initTXChannel())
{ {
Serial.println(DSHOT_MSG_01); Serial.println(DSHOT_MSG_01);
return DSHOT_ERROR; return DSHOT_ERROR;
} }
// Init RX Channel // Inits RX Channel
if (!_initRXChannel() && _is_bidirectional) if (!_initRXChannel() && _is_bidirectional)
{ {
Serial.println(DSHOT_MSG_02); Serial.println(DSHOT_MSG_02);
return DSHOT_ERROR; return DSHOT_ERROR;
} }
// Init DShot Decoder // Inits DShot Decoder
if (!_initDShotEncoder()) if (!_initDShotEncoder())
{ {
Serial.println(DSHOT_MSG_03); // Serial.println(DSHOT_MSG_03);
return DSHOT_ERROR; return DSHOT_ERROR;
} }
@ -109,7 +112,7 @@ bool DShotRMT::sendCommand(uint16_t command)
// Check for valid command // Check for valid command
if (command < DSHOT_CMD_MOTOR_STOP || command > DSHOT_CMD_MAX) if (command < DSHOT_CMD_MOTOR_STOP || command > DSHOT_CMD_MAX)
{ {
Serial.println(DSHOT_MSG_07); Serial.println(DSHOT_MSG_06);
return DSHOT_ERROR; return DSHOT_ERROR;
} }
@ -123,7 +126,7 @@ uint16_t DShotRMT::getERPM()
{ {
if (!_is_bidirectional || !_rmt_rx_channel) if (!_is_bidirectional || !_rmt_rx_channel)
{ {
Serial.println(DSHOT_MSG_08); Serial.println(DSHOT_MSG_07);
return _last_erpm; return _last_erpm;
} }
@ -131,7 +134,7 @@ uint16_t DShotRMT::getERPM()
rmt_symbol_word_t _rx_symbols[RX_BUFFER_SIZE]; rmt_symbol_word_t _rx_symbols[RX_BUFFER_SIZE];
if (!rmt_receive(_rmt_rx_channel, _rx_symbols, DSHOT_SYMBOLS_SIZE, &_receive_config)) if (!rmt_receive(_rmt_rx_channel, _rx_symbols, DSHOT_SYMBOLS_SIZE, &_receive_config))
{ {
Serial.println(DSHOT_MSG_09); Serial.println(DSHOT_MSG_08);
return _last_erpm; return _last_erpm;
} }
@ -152,10 +155,9 @@ uint32_t DShotRMT::getMotorRPM(uint8_t magnet_count)
return getERPM() / pole_pairs; return getERPM() / pole_pairs;
} }
// // --- RMT TX Config ---
bool DShotRMT::_initTXChannel() bool DShotRMT::_initTXChannel()
{ {
// --- RMT TX Config ---
_tx_channel_config.gpio_num = _gpio; _tx_channel_config.gpio_num = _gpio;
_tx_channel_config.clk_src = DSHOT_CLOCK_SRC_DEFAULT; _tx_channel_config.clk_src = DSHOT_CLOCK_SRC_DEFAULT;
_tx_channel_config.resolution_hz = DSHOT_RMT_RESOLUTION; _tx_channel_config.resolution_hz = DSHOT_RMT_RESOLUTION;
@ -171,46 +173,55 @@ bool DShotRMT::_initTXChannel()
// Creates and activates RMT TX Channel // Creates and activates RMT TX Channel
if (rmt_new_tx_channel(&_tx_channel_config, &_rmt_tx_channel) != DSHOT_OK) if (rmt_new_tx_channel(&_tx_channel_config, &_rmt_tx_channel) != DSHOT_OK)
{ {
Serial.println(DSHOT_MSG_01);
return DSHOT_ERROR; return DSHOT_ERROR;
} }
return (rmt_enable(_rmt_tx_channel) == 0); return (rmt_enable(_rmt_tx_channel) == DSHOT_OK);
} }
// // --- RMT RX Config ---
bool DShotRMT::_initRXChannel() bool DShotRMT::_initRXChannel()
{ {
// --- RMT RX Config ---
_rx_channel_config.gpio_num = _gpio; _rx_channel_config.gpio_num = _gpio;
_rx_channel_config.clk_src = DSHOT_CLOCK_SRC_DEFAULT; _rx_channel_config.clk_src = DSHOT_CLOCK_SRC_DEFAULT;
_rx_channel_config.resolution_hz = DSHOT_RMT_RESOLUTION; _rx_channel_config.resolution_hz = DSHOT_RMT_RESOLUTION;
_rx_channel_config.mem_block_symbols = DSHOT_SYMBOLS_SIZE; _rx_channel_config.mem_block_symbols = DSHOT_SYMBOLS_SIZE;
// TODO: need to figure out // TODO: figure out ranges
_receive_config.signal_range_min_ns = 2; _receive_config.signal_range_min_ns = 2;
_receive_config.signal_range_max_ns = 128; _receive_config.signal_range_max_ns = 128;
// Creates and activates RMT TX Channel // Creates and activates RMT TX Channel
if (rmt_new_rx_channel(&_rx_channel_config, &_rmt_rx_channel) != DSHOT_OK) if (rmt_new_rx_channel(&_rx_channel_config, &_rmt_rx_channel) != DSHOT_OK)
{ {
Serial.println(DSHOT_MSG_02);
return DSHOT_ERROR; return DSHOT_ERROR;
} }
return (rmt_enable(_rmt_rx_channel) == 0); return (rmt_enable(_rmt_rx_channel) == DSHOT_OK);
} }
// // --- RMT Encoder Config ---
bool DShotRMT::_initDShotEncoder() bool DShotRMT::_initDShotEncoder()
{ {
// Creates a dummy encoder // Encoder "config"
rmt_copy_encoder_config_t encoder_config = {}; rmt_copy_encoder_config_t encoder_config = {};
return rmt_new_copy_encoder(&encoder_config, &_dshot_encoder) == 0;
// Creates a dummy encoder
if (rmt_new_copy_encoder(&encoder_config, &_dshot_encoder) != DSHOT_OK)
{
Serial.println(DSHOT_MSG_03);
return DSHOT_ERROR;
}
return DSHOT_OK;
} }
// Use RMT to transmit a prepared DShot packet and returns it // Uses 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)
{ {
// Excludes calculation from timing is more stable // Excluding calculation from timing is more timing 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);
@ -257,15 +268,15 @@ dshot_packet_t DShotRMT::_buildDShotPacket(const uint16_t value)
// Creates DShot packet // Creates DShot packet
packet.throttle_value = value; packet.throttle_value = value;
packet.telemetric_request = 1; // needed to get the motor spinning packet.telemetric_request = 1; // needed to get the motor spinning
packet.checksum = _calculateCRC(packet); packet.checksum = _calculateCRC(packet);
// //
return packet; return packet;
} }
// Encodes DShot packet into RMT buffer // Encodes DShot packet into RMT buffer and places code into IRAM instead of flash
bool IRAM_ATTR DShotRMT::_encodeDShotFrame(const dshot_packet_t &packet, rmt_symbol_word_t *symbols) bool DShotRMT::_encodeDShotFrame(const dshot_packet_t &packet, rmt_symbol_word_t *symbols)
{ {
// Parse actual packet into buffer // Parse actual packet into buffer
_current_packet = _parseDShotPacket(packet); _current_packet = _parseDShotPacket(packet);
@ -330,7 +341,7 @@ uint16_t DShotRMT::_decodeDShotFrame(const rmt_symbol_word_t *symbols)
// Timer triggered // Timer triggered
bool DShotRMT::_timer_signal() bool DShotRMT::_timer_signal()
{ {
return (micros() - _last_transmission_time) >= _frame_timer_us; return (micros() - _last_transmission_time >= _frame_timer_us);
} }
// Updates timestamp // Updates timestamp

55
DShotRMT.h
View File

@ -15,20 +15,20 @@
#include <driver/rmt_rx.h> #include <driver/rmt_rx.h>
// --- DShot Protocol Constants --- // --- DShot Protocol Constants ---
static constexpr uint16_t DSHOT_THROTTLE_FAILSAFE = 0; static constexpr auto DSHOT_THROTTLE_FAILSAFE = 0;
static constexpr uint16_t DSHOT_THROTTLE_MIN = 48; static constexpr auto DSHOT_THROTTLE_MIN = 48;
static constexpr uint16_t DSHOT_THROTTLE_MAX = 2047; static constexpr auto DSHOT_THROTTLE_MAX = 2047;
static constexpr uint8_t DSHOT_BITS_PER_FRAME = 16; static constexpr auto DSHOT_BITS_PER_FRAME = 16;
static constexpr uint8_t DSHOT_SWITCH_TIME = 300; // 30us static constexpr auto DSHOT_SWITCH_TIME = 30; // 30us
static constexpr uint16_t DSHOT_NULL_PACKET = 0b0000000000000000; static constexpr auto DSHOT_NULL_PACKET = 0b0000000000000000;
// --- RMT Config Constants --- // --- RMT Config Constants ---
static constexpr rmt_clock_source_t DSHOT_CLOCK_SRC_DEFAULT = RMT_CLK_SRC_DEFAULT; static constexpr auto DSHOT_CLOCK_SRC_DEFAULT = RMT_CLK_SRC_DEFAULT;
static constexpr uint32_t DSHOT_RMT_RESOLUTION = 10 * 1000 * 1000; // 10 MHz static constexpr auto DSHOT_RMT_RESOLUTION = 10 * 1000 * 1000; // 10 MHz
static constexpr size_t TX_BUFFER_SIZE = DSHOT_BITS_PER_FRAME; static constexpr auto TX_BUFFER_SIZE = DSHOT_BITS_PER_FRAME;
static constexpr size_t RX_BUFFER_SIZE = 64; // debug static constexpr auto RX_BUFFER_SIZE = 64; // debug
static constexpr size_t DSHOT_SYMBOLS_SIZE = 64; static constexpr auto DSHOT_SYMBOLS_SIZE = 64;
// --- DShot Mode Select --- // --- DShot Mode Select ---
typedef enum dshot_mode_e typedef enum dshot_mode_e
@ -59,6 +59,7 @@ typedef struct dshot_timing_s
uint16_t ticks_zero_low; uint16_t ticks_zero_low;
} dshot_timing_t; } dshot_timing_t;
// Some typedef magic for DShot timing config
extern const dshot_timing_t DSHOT_TIMINGS[]; extern const dshot_timing_t DSHOT_TIMINGS[];
// --- DShotRMT Class --- // --- DShotRMT Class ---
@ -73,11 +74,11 @@ public:
bool begin(); bool begin();
// Sets the throttle value and transmits // Sets the throttle value and transmits
bool setThrottle(uint16_t throttle); // deprecated bool setThrottle(uint16_t throttle); // deprecated
bool sendThrottle(uint16_t throttle); bool sendThrottle(uint16_t throttle);
// Sends a DShot Command // Sends a DShot Command
bool sendDShotCommand(uint16_t command); // deprecated bool sendDShotCommand(uint16_t command); // deprecated
bool sendCommand(uint16_t command); bool sendCommand(uint16_t command);
// Gets eRPM from ESC telemetry // Gets eRPM from ESC telemetry
@ -86,10 +87,10 @@ public:
// Converts eRPM to motor RPM // Converts eRPM to motor RPM
uint32_t getMotorRPM(uint8_t magnet_count); uint32_t getMotorRPM(uint8_t magnet_count);
// Returns GPIO Pin // Returns pin number
uint16_t getGPIO() const { return _gpio; } uint16_t getGPIO() const { return _gpio; }
// Returns "raw" Dshot packet sent by RMT // Debug: returns "raw" Dshot packet sent by RMT
uint16_t getDShotPacket() const { return _current_packet; } uint16_t getDShotPacket() const { return _current_packet; }
// //
@ -120,7 +121,7 @@ private:
uint16_t _last_erpm; uint16_t _last_erpm;
uint16_t _current_packet; uint16_t _current_packet;
dshot_packet_t _packet; dshot_packet_t _packet;
unsigned long _last_transmission_time; uint32_t _last_transmission_time;
// ---Helpers --- // ---Helpers ---
bool _initTXChannel(); bool _initTXChannel();
@ -131,7 +132,7 @@ private:
uint16_t _calculateCRC(const dshot_packet_t &packet); uint16_t _calculateCRC(const dshot_packet_t &packet);
dshot_packet_t _buildDShotPacket(const uint16_t value); dshot_packet_t _buildDShotPacket(const uint16_t value);
uint16_t _parseDShotPacket(const dshot_packet_t &packet); uint16_t _parseDShotPacket(const dshot_packet_t &packet);
bool IRAM_ATTR _encodeDShotFrame(const dshot_packet_t &packet, rmt_symbol_word_t *symbols); bool _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 --- // --- Simple Timer ---
@ -139,14 +140,14 @@ private:
bool _timer_reset(); bool _timer_reset();
// --- Error Handling --- // --- Error Handling ---
static constexpr bool DSHOT_OK = 0; static constexpr auto DSHOT_OK = 0;
static constexpr bool DSHOT_ERROR = 1; static constexpr auto DSHOT_ERROR = 1;
static constexpr char *DSHOT_MSG_01 = "Failed to initialize TX channel!"; static constexpr auto *DSHOT_MSG_01 = "Failed to initialize TX channel!";
static constexpr char *DSHOT_MSG_02 = "Failed to initialize RX channe!l"; static constexpr auto *DSHOT_MSG_02 = "Failed to initialize RX channe!l";
static constexpr char *DSHOT_MSG_03 = "Failed to initialize encoder!"; static constexpr auto *DSHOT_MSG_03 = "Failed to initialize DShot encoder!";
static constexpr char *DSHOT_MSG_04 = "RX CRC Check failed!"; static constexpr auto *DSHOT_MSG_04 = "RX CRC Check failed!";
static constexpr char *DSHOT_MSG_06 = "Throttle value not in range (48 - 2047)!"; static constexpr auto *DSHOT_MSG_05 = "Throttle value not in range (48 - 2047)!";
static constexpr char *DSHOT_MSG_07 = "Not a valid DShot Command (0 - 47)!"; static constexpr auto *DSHOT_MSG_06 = "Not a valid DShot Command (0 - 47)!";
static constexpr char *DSHOT_MSG_08 = "Bidirectional DShot support not enabled!"; static constexpr auto *DSHOT_MSG_07 = "Bidirectional DShot support not enabled!";
static constexpr char *DSHOT_MSG_09 = "RX RMT module failure!"; static constexpr auto *DSHOT_MSG_08 = "RX RMT module failure!";
}; };

31
examples/dshot300/dshot300.ino
View File

@ -13,8 +13,7 @@
static constexpr auto &USB_SERIAL = Serial0; static constexpr auto &USB_SERIAL = Serial0;
static constexpr auto USB_SERIAL_BAUD = 115200; static constexpr auto USB_SERIAL_BAUD = 115200;
// Motor configuration // Motor configuration - Pin number or GPIO_PIN
// Pin number or GPIO_PIN
// static constexpr gpio_num_t MOTOR01_PIN = GPIO_NUM_17; // static constexpr gpio_num_t MOTOR01_PIN = GPIO_NUM_17;
static constexpr auto MOTOR01_PIN = 17; static constexpr auto MOTOR01_PIN = 17;
@ -22,27 +21,24 @@ static constexpr auto MOTOR01_PIN = 17;
static constexpr dshot_mode_t DSHOT_MODE = DSHOT300; static constexpr dshot_mode_t DSHOT_MODE = DSHOT300;
// BiDirectional DShot Support (default: false) // BiDirectional DShot Support (default: false)
static constexpr bool IS_BIDIRECTIONAL = false; static constexpr auto IS_BIDIRECTIONAL = false;
// Motor magnet count for RPM calculation // Motor magnet count for RPM calculation
static constexpr auto MOTOR01_MAGNET_COUNT = 14; static constexpr auto MOTOR01_MAGNET_COUNT = 14;
// //
// Create the motor instance // Creates the motor instance
DShotRMT motor01(MOTOR01_PIN, DSHOT_MODE, IS_BIDIRECTIONAL); DShotRMT motor01(MOTOR01_PIN, DSHOT_MODE, IS_BIDIRECTIONAL);
// //
void setup() void setup()
{ {
// Start the USB Serial Port // Starts the USB Serial Port
USB_SERIAL.begin(USB_SERIAL_BAUD); USB_SERIAL.begin(USB_SERIAL_BAUD);
// Initialize DShot Signal // Initializes DShot Signal
motor01.begin(); motor01.begin();
// Arm ESC with minimum throttle
// motor01.sendThrottle(DSHOT_THROTTLE_MIN);
USB_SERIAL.println("***********************************"); USB_SERIAL.println("***********************************");
USB_SERIAL.println(" === DShotRMT Demo started. === "); USB_SERIAL.println(" === DShotRMT Demo started. === ");
USB_SERIAL.println("Enter a throttle value (48 – 2047):"); USB_SERIAL.println("Enter a throttle value (48 – 2047):");
@ -51,18 +47,17 @@ void setup()
// //
void loop() void loop()
{ {
// Safety first: start with DSHOT_MIN_THROTTLE
static auto throttle = DSHOT_THROTTLE_MIN; static auto throttle = DSHOT_THROTTLE_MIN;
// Takes "every" throttle value
if (USB_SERIAL.available() > NULL) if (USB_SERIAL.available() > NULL)
{ {
auto new_throttle = (USB_SERIAL.readStringUntil('\n').toInt()); throttle = (USB_SERIAL.readStringUntil('\n').toInt());
USB_SERIAL.println("*********************"); USB_SERIAL.println("*********************");
USB_SERIAL.print("Throttle set to: "); USB_SERIAL.print("Throttle set to: ");
USB_SERIAL.println(new_throttle); USB_SERIAL.println(throttle);
//
throttle = new_throttle;
} }
// Sends the value to the ESC // Sends the value to the ESC
@ -75,12 +70,12 @@ void loop()
print_RMT_packet(2000); print_RMT_packet(2000);
} }
// Prints RPM every ms // Prints RPM every X_ms
void printRPMPeriodically(auto timer_ms) void printRPMPeriodically(auto timer_ms)
{ {
if (IS_BIDIRECTIONAL) if (IS_BIDIRECTIONAL)
{ {
static unsigned long last_print_time = 0; static auto last_print_time = 0;
if (millis() - last_print_time >= timer_ms) if (millis() - last_print_time >= timer_ms)
{ {
@ -97,14 +92,14 @@ void printRPMPeriodically(auto timer_ms)
// Prints "raw" packet every ms // Prints "raw" packet every ms
void print_RMT_packet(auto timer_ms) void print_RMT_packet(auto timer_ms)
{ {
static unsigned long last_print_time = 0; static auto last_print_time = 0;
if (millis() - last_print_time >= timer_ms) if (millis() - last_print_time >= timer_ms)
{ {
auto packet = motor01.getDShotPacket(); auto packet = motor01.getDShotPacket();
// Print bit by bit // Print bit by bit
for (int i = 15; i >= 0; --i) for (auto i = 15; i >= 0; --i)
{ {
if ((packet >> i) & 1) if ((packet >> i) & 1)
{ {