config interface

Quadcopter Configuration

Interface

void text_debug() {

// ...

serial_printf("rc_throttle: %8.3f", rc_get(RC_THROTTLE)); serial_printf("\t m1: %d", motor_level(M1)); serial_printf("\t m2: %d", motor_level(M2)); serial_printf("\t m3: %d", motor_level(M3)); serial_printf("\t m4: %d", motor_level(M4)); serial_printlnf("");

}

Debugging with the console

Demo

Going wireless

bluetooth10 meters Radio telemetry

500m ++

• Chrome Packaged App

• Python with PySide (Qt)

• Electron (NodeJS)

Options

Python with PySide (Qt)

Electron

https://github.com/sindresorhus/awesome-electron

Electron

Electron

So, we can use Node SerialPort!

var SerialPort = require(“serialport").SerialPort

var serialPort = new SerialPort("/dev/tty-usbserial1", { baudrate: 57600 });

const onDataReceived = function(data) { processData(data); }

Electron

Start with a boilerplate!

Storing and passing configuration data

On the C side:typedef struct {

uint16_t version; uint16_t motors_min; uint16_t motors_max;

} CONFIG_struct;

JavaScript:let config = { version: 1, motors_min: 0, motors_max: 2000 }

Config struct requirementstypedef struct {

} CONFIG_struct;

1. ability to access the config data from anywhere in the program ( e.g. CONFIG.motors_min )

2. Ability to serialize the struct to binary to pass in the packet

[version][motors_min][motors_max]

} CONFIG_struct;

in memory (each 16 bits):

[version][motors_min][motors_max]

typedef struct __attribute__((packed)) {

} CONFIG_struct;

mark the struct as “packed”, ensure that there is no padding between values

typedef struct __attribute__((packed)) { uint16_t version; uint16_t motor_min; uint16_t motor_max; } CONFIG_struct;

typedef union { CONFIG_struct data; uint8_t raw[sizeof(CONFIG_struct)]; } CONFIG_union;

extern CONFIG_union CONFIG;

Config data struct

// anywhere in the code

make_something_happen(CONFIG.data.max);

Config data struct

Config data struct

Config data struct

Config data struct

void config_update_eeprom() { for (uint16_t i = 0; i < sizeof(CONFIG); i++) { EEPROM.update(i, CONFIG.raw[i]); } }

var buffer = new ArrayBuffer(6) fillInArrayBufferFromSerialPort(buffer)

var dataView = new DataView(buffer)

var version = dataview.getUint16(0) var motorMin = dataview.getUint16(2) var motorMax = dataview.getUint16(4)

Config data - JavaScriptArrayBuffer & DataView

} CONFIG_struct;

JavaScript:let config = { version: 1, motors_min: 0, motors_max: 2000 }

set_config 1.00 0 2000

Sending data both ways? (configuration)

Simple approach - print text:

(but difficult to parse text and no error checking)

[HEADER1][HEADER2][CODE][LENGTH_LSB][LENGTH_MSB][DATA][CRC]

Better approach: Binary packets

Binary packet example

• JavaScript app sends a packet with a code of REQUEST_CONFIG and no data

• The micro controller responds with a packet with a code of REQUEST_CONFIG that contains all of the configuration data

Binary packets

#define PACKET_HEADER1 0x02 #define PACKET_HEADER2 0xB5

Headers - indicate the start of a packet

Binary packets

#define REQUEST_CONFIG 1 #define REQUEST_GYRO_ACC 2 #define REQUEST_RC 3 #define REQUEST_MOTORS 4 #define REQUEST_RATE_PIDS 5

#define SET_CONFIG 101

#define INFO_SUCCESS 201 #define INFO_FAILURE 202 #define INFO_BAD_CRC 203

Code - explains what the packet is about

Binary packets

Length - how many bytes of data is being transmitted

Binary packets

Data - binary data

We keep reading this until we get to the number of bytes stated in the LENGTH section of the packet

Binary packets

CRC - cyclic redundancy check

This is a code that is calculated based on the data within the packet.

When the packet is received, the client calculates the CRC on their own, and ensure that it matches what is specified here

CRC Calculation

Calculated by XOR’ing the binary representation of all of the bytes of the packet body

Packet processing code: processCommand(data) { switch(this.state) { case 0: if (data === serialCodes.PACKET_HEADER1) { this.state++; } break; case 1: if (data === serialCodes.PACKET_HEADER2) { this.state++; } else { this.state = 0; } break; case 2: this.code = data; this.incomingCrc = data; this.state++; break;