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This commit is contained in:
Wastl Kraus 2023-04-15 07:45:14 +02:00
parent a8c2ccaaea
commit 4e84b2e5e7
2 changed files with 102 additions and 91 deletions
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142
DShotRMT.cpp
View File

@ -6,27 +6,29 @@
#include <DShotRMT.h>
// Constructor that takes gpio and rmtChannel as arguments
DShotRMT::DShotRMT(gpio_num_t gpio, rmt_channel_t rmtChannel)
{
// Initialize the configuration structure
// Initialize the dshot_config structure with the arguments passed to the constructor
dshot_config.gpio_num = gpio;
dshot_config.pin_num = uint8_t(gpio);
dshot_config.pin_num = static_cast<uint8_t>(gpio);
dshot_config.rmt_channel = rmtChannel;
dshot_config.mem_block_num = uint8_t(RMT_CHANNEL_MAX - uint8_t(rmtChannel));
dshot_config.mem_block_num = static_cast<uint8_t>(RMT_CHANNEL_MAX - static_cast<uint8_t>(rmtChannel));
// ...create empty packet
// Create an empty packet using the DSHOT_NULL_PACKET and the buildTxRmtItem function
buildTxRmtItem(DSHOT_NULL_PACKET);
}
// Constructor that takes pin and channel as arguments
DShotRMT::DShotRMT(uint8_t pin, uint8_t channel)
{
// Initialize the configuration structure
dshot_config.gpio_num = gpio_num_t(pin);
// Initialize the dshot_config structure with the arguments passed to the constructor
dshot_config.gpio_num = static_cast<gpio_num_t>(pin);
dshot_config.pin_num = pin;
dshot_config.rmt_channel = rmt_channel_t(channel);
dshot_config.mem_block_num = (RMT_CHANNEL_MAX - channel);
dshot_config.rmt_channel = static_cast<rmt_channel_t>(channel);
dshot_config.mem_block_num = RMT_CHANNEL_MAX - channel;
// ...create empty packet
// Create an empty packet using the DSHOT_NULL_PACKET and the buildTxRmtItem function
buildTxRmtItem(DSHOT_NULL_PACKET);
}
@ -43,59 +45,62 @@ DShotRMT::DShotRMT(DShotRMT const &)
bool DShotRMT::begin(dshot_mode_t dshot_mode, bool is_bidirectional)
{
// Set DShot configuration parameters based on input parameters
dshot_config.mode = dshot_mode;
dshot_config.clk_div = DSHOT_CLK_DIVIDER;
dshot_config.name_str = dshot_mode_name[dshot_mode];
dshot_config.is_bidirectional = is_bidirectional;
// Set timing parameters based on selected DShot mode
switch (dshot_config.mode)
{
case DSHOT150:
dshot_config.ticks_per_bit = 64; // ...Bit Period Time 6.67 us
dshot_config.ticks_zero_high = 24; // ...zero time 2.50 us
dshot_config.ticks_one_high = 48; // ...one time 5.00 us
dshot_config.ticks_per_bit = 64;
dshot_config.ticks_zero_high = 24;
dshot_config.ticks_one_high = 48;
break;
case DSHOT300:
dshot_config.ticks_per_bit = 32; // ...Bit Period Time 3.33 us
dshot_config.ticks_zero_high = 12; // ...zero time 1.25 us
dshot_config.ticks_one_high = 24; // ...one time 2.50 us
dshot_config.ticks_per_bit = 32;
dshot_config.ticks_zero_high = 12;
dshot_config.ticks_one_high = 24;
break;
case DSHOT600:
dshot_config.ticks_per_bit = 16; // ...Bit Period Time 1.67 us
dshot_config.ticks_zero_high = 6; // ...zero time 0.625 us
dshot_config.ticks_one_high = 12; // ...one time 1.25 us
dshot_config.ticks_per_bit = 16;
dshot_config.ticks_zero_high = 6;
dshot_config.ticks_one_high = 12;
break;
case DSHOT1200:
dshot_config.ticks_per_bit = 8; // ...Bit Period Time 0.83 us
dshot_config.ticks_zero_high = 3; // ...zero time 0.313 us
dshot_config.ticks_one_high = 6; // ...one time 0.625 us
dshot_config.ticks_per_bit = 8;
dshot_config.ticks_zero_high = 3;
dshot_config.ticks_one_high = 6;
break;
// ...because having a default is "good style"
// Default case to handle invalid input
default:
dshot_config.ticks_per_bit = 0; // ...Bit Period Time endless
dshot_config.ticks_zero_high = 0; // ...no bits, no time
dshot_config.ticks_one_high = 0; // ......no bits, no time
dshot_config.ticks_per_bit = 0;
dshot_config.ticks_zero_high = 0;
dshot_config.ticks_one_high = 0;
break;
}
// ...calc low signal timing
// Calculate low signal timing
dshot_config.ticks_zero_low = (dshot_config.ticks_per_bit - dshot_config.ticks_zero_high);
dshot_config.ticks_one_low = (dshot_config.ticks_per_bit - dshot_config.ticks_one_high);
// Set up RMT configuration for DShot transmission
dshot_tx_rmt_config.rmt_mode = RMT_MODE_TX;
dshot_tx_rmt_config.channel = dshot_config.rmt_channel;
dshot_tx_rmt_config.gpio_num = dshot_config.gpio_num;
dshot_tx_rmt_config.mem_block_num = dshot_config.mem_block_num;
dshot_tx_rmt_config.clk_div = dshot_config.clk_div;
dshot_tx_rmt_config.tx_config.loop_en = false;
dshot_tx_rmt_config.tx_config.carrier_en = false;
dshot_tx_rmt_config.tx_config.idle_output_en = true;
// Set idle level for RMT transmission based on input parameter
if (dshot_config.is_bidirectional)
{
dshot_tx_rmt_config.tx_config.idle_level = RMT_IDLE_LEVEL_HIGH;
@ -105,87 +110,94 @@ bool DShotRMT::begin(dshot_mode_t dshot_mode, bool is_bidirectional)
dshot_tx_rmt_config.tx_config.idle_level = RMT_IDLE_LEVEL_LOW;
}
// ...setup selected dshot mode
// Set up selected DShot mode
rmt_config(&dshot_tx_rmt_config);
// ...essential step, return the result
// Install RMT driver and return result
return rmt_driver_install(dshot_tx_rmt_config.channel, 0, 0);
}
// ...the config part is done, now the calculating and sending part
// void DShotRMT::sendThrottleValue(uint16_t throttle_value, telemetric_request_t telemetric_request)
// Define a function to send a DShot command over an RMT interface to control a brushless motor's speed.
void DShotRMT::sendThrottleValue(uint16_t throttle_value)
{
dshot_packet_t dshot_rmt_packet = {};
// Check if the throttle value is less than the minimum allowed value for the DShot protocol.
if (throttle_value < DSHOT_THROTTLE_MIN)
{
throttle_value = DSHOT_THROTTLE_MIN;
}
// Check if the throttle value is greater than the maximum allowed value for the DShot protocol.
if (throttle_value > DSHOT_THROTTLE_MAX)
{
throttle_value = DSHOT_THROTTLE_MAX;
}
// ...packets are the same for bidirectional mode
dshot_rmt_packet.throttle_value = throttle_value;
// dshot_rmt_packet.telemetric_request = telemetric_request;
// Telemetric using additional pin on the ESC is not supported.
dshot_rmt_packet.telemetric_request = NO_TELEMETRIC;
// Calculate the checksum for the DShot packet using the calculateCRC function.
dshot_rmt_packet.checksum = calculateCRC(dshot_rmt_packet);
// Send the DShot packet over the RMT interface to control the motor's speed.
sendRmtPaket(dshot_rmt_packet);
}
// This method builds the RMT data transmission sequence for the DShot protocol
rmt_item32_t *DShotRMT::buildTxRmtItem(uint16_t parsed_packet)
{
// ...for bidirectional mode
// Check if DShot is set to bidirectional mode
if (dshot_config.is_bidirectional)
{
// ..."invert" the high / low bits
// If bidirectional, invert the high/low bits
for (int i = 0; i < DSHOT_PAUSE_BIT; i++, parsed_packet <<= 1)
{
if (parsed_packet & 0b1000000000000000)
{
// set one
// Set RMT item for a logic high signal
dshot_tx_rmt_item[i].duration0 = dshot_config.ticks_one_low;
dshot_tx_rmt_item[i].duration1 = dshot_config.ticks_one_high;
}
else
{
// set zero
// Set RMT item for a logic low signal
dshot_tx_rmt_item[i].duration0 = dshot_config.ticks_zero_low;
dshot_tx_rmt_item[i].duration1 = dshot_config.ticks_zero_high;
}
// Set level of RMT item
dshot_tx_rmt_item[i].level0 = 0;
dshot_tx_rmt_item[i].level1 = 1;
}
}
// ..."normal" DShot mode / "bidirectional" mode OFF
else
{
// If not bidirectional, set the RMT items as usual
for (int i = 0; i < DSHOT_PAUSE_BIT; i++, parsed_packet <<= 1)
{
if (parsed_packet & 0b1000000000000000)
{
// set one
// Set RMT item for a logic high signal
dshot_tx_rmt_item[i].duration0 = dshot_config.ticks_one_high;
dshot_tx_rmt_item[i].duration1 = dshot_config.ticks_one_low;
}
else
{
// set zero
// Set RMT item for a logic low signal
dshot_tx_rmt_item[i].duration0 = dshot_config.ticks_zero_high;
dshot_tx_rmt_item[i].duration1 = dshot_config.ticks_zero_low;
}
// Set level of RMT item
dshot_tx_rmt_item[i].level0 = 1;
dshot_tx_rmt_item[i].level1 = 0;
}
}
// Set end marker for each frame
if (dshot_config.is_bidirectional)
{
dshot_tx_rmt_item[DSHOT_PAUSE_BIT].level0 = 1;
@ -197,39 +209,37 @@ rmt_item32_t *DShotRMT::buildTxRmtItem(uint16_t parsed_packet)
dshot_tx_rmt_item[DSHOT_PAUSE_BIT].level1 = 1;
}
// ...end marker added to each frame
// Add packet seperator aka DShot Pause.
dshot_tx_rmt_item[DSHOT_PAUSE_BIT].duration1 = DSHOT_PAUSE;
// Return the rmt_item
return dshot_tx_rmt_item;
}
// Legacy CRC calculation
// uint16_t DShotRMT::calculateCRC(const dshot_packet_t &dshot_packet)
// {
// uint16_t packet = DSHOT_NULL_PACKET;
// uint16_t crc = DSHOT_NULL_PACKET;
// // Same initial 11 bits for both bidirectional and normal mode
// packet = (dshot_packet.throttle_value << 1) | dshot_packet.telemetric_request;
// if (dshot_config.is_bidirectional)
// {
// // Calculate checksum in inverted/bidirectional mode
// crc = (~(packet ^ (packet >> 4) ^ (packet >> 8))) & 0x0F;
// }
// else
// {
// // Calculate checksum in normal mode
// crc = (packet ^ (packet >> 4) ^ (packet >> 8)) & 0x0F;
// }
// return crc;
// }
// New way of calculating CRC
// Calculates a CRC value for a DShot digital control signal packet
uint16_t DShotRMT::calculateCRC(const dshot_packet_t &dshot_packet)
{
uint16_t crc;
// Combine the throttle value and telemetric request flag into a 16-bit packet value
const uint16_t packet = (dshot_packet.throttle_value << 1) | dshot_packet.telemetric_request;
const uint16_t crc = dshot_config.is_bidirectional
? (~(packet ^ (packet >> 4) ^ (packet >> 8))) & 0x0F
: (packet ^ (packet >> 4) ^ (packet >> 8)) & 0x0F;
// Calculate the CRC value using different bitwise operations depending on the DShot configuration
if (dshot_config.is_bidirectional)
{
// Bidirectional configuration: perform a bitwise negation of the result of XORing the packet with its right-shifted values by 4 and 8 bits,
// and then bitwise AND the result with 0x0F
const uint16_t intermediate_result = packet ^ (packet >> 4) ^ (packet >> 8);
crc = (~intermediate_result) & 0x0F;
}
else
{
// Unidirectional configuration: XOR the packet with its right-shifted values by 4 and 8 bits,
// and then bitwise AND the result with 0x0F
crc = (packet ^ (packet >> 4) ^ (packet >> 8)) & 0x0F;
}
// Return the calculated CRC value as a 16-bit unsigned integer
return crc;
}

3
DShotRMT.h
View File

@ -86,7 +86,8 @@ typedef struct dshot_config_s
} dshot_config_t;
// The official DShot Commands
typedef enum dshot_cmd_e {
typedef enum dshot_cmd_e
{
DSHOT_CMD_MOTOR_STOP = 0, // Currently not implemented - STOP Motors
DSHOT_CMD_BEEP1, // Wait at least length of beep (380ms) before next command
DSHOT_CMD_BEEP2, // Wait at least length of beep (380ms) before next command