This was developped in order to communicate with the udriver boards using a raspberry following this description of the protocol.
This implementation uses the spidev kernel module.
In order to use the sofware, you will need an spidev device detected by linux.
We briefly explain how to achieve that on a raspberry below.
Using make inside src folder will create a build folder containing the headers and the shared library file.
Using make inside the exemple folder will create an exec file.
This program will open the device /dev/spidev0.0 and send a packet every second to the udriver board.
The board should initialize motor1 and maintain its position.
exec has to be launch with the appropriate permission in order to access /dev/spidev0.0.
In order to activate spi capabilities, the following line should be added to config.txt
dtparam=spi=on
After reboot, /dev/spidev0.0 and /devspidev0.1 should appear.
/dev/spidev0.0 for the CE0 slave line and /dev/spidev0.1 for the CE1 slave line.
You can now plug your spi device using the right GPIO pins.
For /dev/spidev0.0 and /dev/spidev0.1, its gpio 7,8,9,10 and 11.
You can also activate other spi device on the gpio pins with the following lines in config.txt.
dtoverlay=spi1-1cs #1 chip select
dtoverlay=spi1-2cs #2 chip select
dtoverlay=spi1-3cs #3 chip select
Depending of the raspberry version some might be available or not.
For more info : raspberry spi readme
An Spi_Interface can be created in order to communicate with one spidev device.
Spi_Interface(bool debug = false);If debug is true, some feedback will be provided on stdout.
The functions return 0 on success.
int start(const char *device);
int stop();start will open the specified device (/dev/spidev0.0 for exemple) and configure it.
stop will close the device.
int transmit(command_packet send, sensor_packet *rcv);transmit will send the send packet and fill the rcv packet.
Here are structs describing the command and sensor packets provided
struct command_packet
{
bool enable_system;
bool enable_motor1;
bool enable_motor2;
bool position_rollover;
bool index_offset_compensation_motor1;
bool index_offset_compensation_motor2;
uint8_t timeout;
double position_motor1; // Unit : turn Min : -128 Max : 127,999999940395
double position_motor2;
double velocity_motor1; // Unit : k rpm Min : -16 Max : 15,9995117188
double velocity_motor2;
double iq_motor1; // Unit : A Min : -32 Max : 31,9990234375
double iq_motor2;
double Kp_motor1; // Unit : A/rot Min : 0 Max : 31.99951171875
double Kp_motor2;
double Kd_motor1; // Unit : A/k rpm Min : 0 Max : 63.9990234375
double Kd_motor2;
double I_sat_motor1; // Unit : A Min : 0 Max : 31,875
double I_sat_motor2;
uint16_t index;
};
struct sensor_packet
{
bool system_enabled;
bool motor1_enabled;
bool motor2_enabled;
bool motor1_ready;
bool motor2_ready;
bool index_1_detected;
bool index_2_detected;
bool index_1_toggle;
bool index_2_toggle;
uint8_t error_code;
double position_motor1; // Unit : turn Min : -128 Max : 127,999999940395
double position_motor2;
double velocity_motor1; // Unit : k rpm Min : -16 Max : 15,9995117188
double velocity_motor2;
double iq_motor1; // Unit : A Min : -32 Max : 31,9990234375
double iq_motor2;
double coil_resistance_motor1; // Unit : Ohm Min : 0 Max : 1,9999694824
double coil_resistance_motor2;
double adc_motor1; // Unit : V Min : 0 Max : 3.99993896484
double adc_motor2;
uint16_t last_index;
uint16_t timestamp;
uint32_t crc;
};The error code message signification can be found here.