DShotRMT/src/DShotRMT.h

//
// Name:		DShotRMT.h
// Created: 	20.03.2021 00:49:15
// Author:  	derdoktor667
//

#pragma once

#ifndef _DSHOTRMT_h
#define _DSHOTRMT_h

#if defined(ARDUINO) && ARDUINO >= 100
#include "arduino.h"
#else
#include "WProgram.h"
#endif

// ...utilizing the RMT Module library for generating the DShot signal
#include <driver/rmt.h>

constexpr auto DSHOT_CLK_DIVIDER = 8;    // ...slow down RMT clock to 0.1 microseconds / 100 nanoseconds per cycle
constexpr auto DSHOT_PACKET_LENGTH = 17; // ...last pack is the pause

constexpr auto DSHOT_THROTTLE_MIN = 48;
constexpr auto DSHOT_THROTTLE_MAX = 2047;
constexpr auto DSHOT_NULL_PACKET = 0b0000000000000000;

constexpr auto DSHOT_PAUSE = 21; // ...21bit is recommended, but to be sure
constexpr auto DSHOT_PAUSE_BIT = 16;

constexpr auto F_CPU_RMT = APB_CLK_FREQ;
constexpr auto RMT_CYCLES_PER_SEC = (F_CPU_RMT / DSHOT_CLK_DIVIDER);
constexpr auto RMT_CYCLES_PER_ESP_CYCLE = (F_CPU / RMT_CYCLES_PER_SEC);

typedef enum dshot_mode_e
{
	DSHOT_OFF,
	DSHOT150,
	DSHOT300,
	DSHOT600,
	DSHOT1200
} dshot_mode_t;

// ...to get human readable DShot Mode
static const char* const dshot_mode_name[] = {
	"DSHOT_OFF",
	"DSHOT150",
	"DSHOT300",
	"DSHOT600",
	"DSHOT1200" };

typedef String dshot_name_t;

typedef enum telemetric_request_e
{
	NO_TELEMETRIC,
	ENABLE_TELEMETRIC,
} telemetric_request_t;

// ...set bitcount for DShot packet
typedef struct dshot_packet_s
{
	uint16_t throttle_value : 11;
	telemetric_request_t telemetric_request : 1;
	uint16_t checksum : 4;
} dshot_packet_t;

// ...set bitcount for eRPM packet
typedef struct eRPM_packet_s
{
	uint16_t eRPM_data : 12;
	uint8_t checksum : 4;
} eRPM_packet_t;

// ...all settings for the dshot mode
typedef struct dshot_config_s
{
	dshot_mode_t mode;
	dshot_name_t name_str;
	bool bidirectional;
	gpio_num_t gpio_num;
	uint8_t pin_num;
	rmt_channel_t rmt_channel;
	uint8_t mem_block_num;
	uint16_t ticks_per_bit;
	uint8_t clk_div;
	uint16_t ticks_zero_high;
	uint16_t ticks_zero_low;
	uint16_t ticks_one_high;
	uint16_t ticks_one_low;
} dshot_config_t;

class DShotRMT
{
	public:
	DShotRMT(gpio_num_t gpio, rmt_channel_t rmtChannel);
	DShotRMT(uint8_t pin, uint8_t channel);
	~DShotRMT();
	DShotRMT(DShotRMT const&);

	// ...safety first ...no parameters, no DShot
	bool begin(dshot_mode_t dshot_mode = DSHOT_OFF, bool is_bidirectional = false);
	void send_dshot_value(uint16_t throttle_value, telemetric_request_t telemetric_request = NO_TELEMETRIC);

	dshot_config_t* get_dshot_info();
	uint8_t* get_dshot_clock_div();

	private:
	rmt_item32_t dshot_tx_rmt_item[DSHOT_PACKET_LENGTH];
	rmt_config_t dshot_tx_rmt_config;
	dshot_config_t dshot_config;

	rmt_item32_t* encode_dshot_to_rmt(uint16_t parsed_packet);
	uint16_t calc_dshot_chksum(const dshot_packet_t& dshot_packet);
	uint16_t prepare_rmt_data(const dshot_packet_t& dshot_packet);

	void output_rmt_data(const dshot_packet_t& dshot_packet);
};

#endif