Files
firmware/components/dataLink/include/Frames.h
Johnathon Slightham c14c82ce9c Reduce DataLink latency
2026-01-30 01:44:42 -05:00

117 lines
5.1 KiB
C++

#ifdef DATA_LINK
#pragma once
#include "freertos/FreeRTOS.h"
#include <variant>
#include <cstdint>
#include <vector>
#define BROADCAST_ADDR 0xFF //used for discovery (finding the board's neighbours). this will mean the board ids will have 2^8-2 = 254 unique IDs that could be assigned
#define PC_ADDR 0x0 //setting 0 to be the PC
#define START_OF_FRAME 0xAB //0b1010_1011 - denotes the start of frame
#define MAX_FRAME_SIZE 121 //Max 121B (due to rmt) - note this includes the overhead of the frame. the actual payload max depends on the frame type (eg. 121 - 9 B is the max control data length)
#define MAX_GENERIC_NUM_FRAG (1 << 16) // Max 2**16 Fragments can be made with a generic frame (total 2**16 *MAX_GENERIC_DATA_LEN B of data can be sent ~ 6.7 MiB)
#define MAX_FRAME_QUEUE_SIZE 15 //Size of the queue for the frame scheduler (per channel)
//Flags
#define FLAG_FRAG 0x8 //0b1000 //this fragmented frame is part of a larger frame
#define FLAG_DISCOVERY 0x4 //0b0100
#define FLAG_NEIGH_TABLE 0x2 //0b0010 - used to denote the frame contains the neighbour tables (used for finding the configuration/topology of the network); similar to an ARP or MAC table
#define FLAG_ACK 0x1 //0b0001_0000 - used for confirming receipt of different types of frames from the neighbours
#define GET_TYPE(x) ((x) & 0xF0)
#define GET_FLAG(x) ((x) & 0x0F)
#define MAKE_TYPE_FLAG(type, flag) ((uint8_t)((type & 0xF0) | (flag & 0xF)))
#define IS_CONTROL_FRAME(x) (((x) & 0x80) != 0)
#define CONTROL_FRAME_OVERHEAD 9
#define GENERIC_FRAME_OVERHEAD 14
#define MAX_GENERIC_DATA_LEN (MAX_FRAME_SIZE - GENERIC_FRAME_OVERHEAD)
#define MAX_CONTROL_DATA_LEN (MAX_FRAME_SIZE - CONTROL_FRAME_OVERHEAD)
//Generic Frame Fragment ACK
#define GENERIC_FRAG_ACK_DATA_SIZE 7
#define GENERIC_FRAG_ACK_PREAMBLE 0x69
#define CONTROL_FRAME_TYPE 0x80 //if the frame type MSB is set to 1, use the control frame
//Types (total 2^4 = 16 different types)
enum class FrameType : uint8_t {
//Control Frames
MOTOR_TYPE = 0x80, //0b1000_0000
RIP_TABLE_CONTROL = 0x90, //0b1001_0000 - using the control frame to broadcast the RIP table
DISTANCE_SENSOR_TYPE = 0xA0, //0b1010_0000
SERVO_TYPE = 0xC0, //0b1100_0000
MISC_CONTROL_TYPE = 0xD0, //0b1101_0000
//Generic Frames
MISC_GENERIC_TYPE = 0x00, //0b0000_0000
MISC_UDP_GENERIC_TYPE = 0x10, // 0b0001_0000 - Same as MISC_GENERIC_TYPE except no ACK frames will be expected
SYSTEM_TYPE = 0x30, //0b0011_0000 - used for statuses, discovery, and other maintainence requests
ACK_TYPE = 0x60, //0b0110_0000 - ACK frames for Generic Fragments
RIP_TABLE_GENERIC = 0x70 //0b0111_0000 - using the generic frame to broadcast the RIP table (not used rn)
};
enum class FrameFlags : uint8_t {
ANY_FLAG = 0x0,
};
#pragma pack(push, 1) //these structs will be transmitted as is (ensure the structs are structured using 1B alignment - no padding)
typedef struct _control_frame{
uint8_t preamble; //Start of Frame
uint8_t sender_id; //sender board id
uint8_t receiver_id; //receiver board id
uint16_t seq_num; //sequence number to differentiate frames being sent from sender to receiver
uint8_t type_flag; //(type << 4) | flag - both are 4 bits
uint16_t data_len; //Data Length (max 256B)
uint8_t data[MAX_FRAME_SIZE]; //Variable Length of Data
uint16_t crc_16; //CRC-16
} ControlFrame; //this will have a max size of 9 + 256B = 265B
typedef struct _data_link_frame{
uint8_t preamble; //Start of Frame
uint8_t sender_id; //sender board id
uint8_t receiver_id; //receiver board id
uint16_t seq_num; //sequence number to differentiate frames being sent from sender to receiver
uint8_t type_flag; //(type << 4) | flag - both are 4 bits
uint16_t total_frag; //total number of fragments for this sequence
uint16_t frag_num; //current fragment number
uint16_t data_len; //Data Length (max 178B)
uint8_t data[MAX_FRAME_SIZE]; //Variable Length of Data
uint16_t crc_16; //CRC-16
} GenericFrame; //this will have a max size of 14 + 2^8 B = 270 B
#pragma pack(pop)
typedef struct _header{
uint8_t preamble; //Start of Frame
uint8_t sender_id; //sender board id
uint8_t receiver_id; //receiver board id
uint16_t seq_num; //sequence number to differentiate frames being sent from sender to receiver
uint8_t type_flag; //(type << 4) | flag - both are 4 bits
uint32_t frag_info; //(total_frag_num << 16) | frag_num - total_frag_num denotes the total number of fragmented frames to expect for this sequence number(?) and frag_num denotes the fragment frame num
uint16_t data_len; //Data Length (max 178B)
uint16_t crc_16; //CRC-16
} FrameHeader;
using Frame = std::variant<ControlFrame, GenericFrame>;
ControlFrame make_control_frame_from_header(const FrameHeader& header);
GenericFrame make_generic_frame_from_header(const FrameHeader& header);
typedef struct _fragment_metadata {
std::vector<GenericFrame> fragments;
uint16_t num_fragments_rx;
} FragmentMetadata;
typedef struct _receive_metadata{
std::unique_ptr<std::vector<uint8_t>> data;
uint16_t data_len;
FrameHeader header;
} Rx_Metadata;
#endif //DATA_LINK