VEX Link C API¶

Note

PROS currently officially supports the use of one VEX Radio per brain for VEXLink.

Functions
Enumerated Values

Functions ¶

link_init ¶

Initializes a link on a radio port, with an indicated type.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.

uint32_t link_init(uint8_t port, const char* link_id, link_type_e_t type);

#define LINK_TRANSMITTER_PORT 1
#define LINK_ID "ROBOT1"

void initialize() {
  link_init(LINK_TRANSMITTER_PORT, LINK_ID, E_LINK_TRANSMITTER);
}

Parameters
port	The port of the radio for the intended link.
link_id	Unique link ID in the form of a string, needs to be different from other links in the area.
type	Indicates whether the radio link on the brain is a transmitter or reciever.

Returns: 1 if operation successful or PROS_ERR if the operation failed, setting errno.

link_init_override ¶

Initializes a link on a radio port, with an indicated type and the ability for vexlink to override the controller radio.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.

uint32_t link_init_override(uint8_t port, const char* link_id, link_type_e_t type);

#define LINK_PORT 1
#define LINK_ID "ROBOT1"

void initialize() {
  link_init(LINK_PORT, LINK_ID, E_LINK_TRANSMITTER);
  link_init_override(LINK_PORT, LINK_ID, E_LINK_TRANSMITTER);
}

Parameters
port	The port of the radio for the intended link.
link_id	Unique link ID in the form of a string, needs to be different from other links in the area.
type	Indicates whether the radio link on the brain is a transmitter or reciever.

Returns: 1 if operation successful or PROS_ERR if the operation failed, setting errno.

link_connected ¶

Checks if a radio link on a port is active or not.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.

bool link_connected(uint8_t port);

#define LINK_TRANSMITTER_PORT 1

void opcontrol() {
  while (true) {
    if (link_connected(LINK_TRANSMITTER_PORT)) {
      screen_print(TEXT_MEDIUM, 1, "Link connected!");
    }
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.

Returns: If a radio is connected to a port and it’s connected to a link.

link_raw_receivable_size ¶

Returns the bytes of data available to be read

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.

uint32_t link_raw_receivable_size(uint8_t port);

#define LINK_RECIVER_PORT 1

void opcontrol() {
  while (true) {
    uint32_t receiveable_size = link_raw_receivable_size(LINK_RECIVER_PORT);
    screen_print(TEXT_MEDIUM, 1, "link_raw_receiveable_size: %d", receiveable_size);
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.

Returns: PROS_ERR if port is not a link/radio, else the bytes available to be read by the user.

link_raw_transmittable_size ¶

Returns the bytes of data available in transmission buffer.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.

uint32_t link_raw_transmittable_size(uint8_t port);

#define LINK_TRANSMITTER_PORT 1

void opcontrol() {
  while (true) {
    uint32_t transmittable_size = link_raw_transmittable_size(LINK_TRANSMITTER_PORT);
    screen_print(TEXT_MEDIUM, 1, "link_raw_transmittable_size: %d", transmittable_size);
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.

Returns: PROS_ERR if port is not a link/radio.

link_transmit_raw ¶

Send raw serial data through vexlink.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.
EBUSY - The transmitter buffer is still busy with a previous transmission, and there is no room in the FIFO buffer (queue) to transmit the data.
EINVAL - The data given is NULL

uint32_t link_transmit_raw(uint8_t port, void* data, uint16_t data_size);

#define LINK_TRANSMITTER_PORT 1

void opcontrol() {
  while (true) {
    char* data = "Hello!";
    link_transmit_raw(LINK_TRANSMITTER_PORT, (void*)data, sizeof(*data) * sizeof(data));
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.
data	Buffer with data to send
data_size	Bytes of data to be read to the destination buffer

Returns: PROS_ERR if port is not a link, 0 if the link is busy, and 1 if it succeeded.

link_receive_raw ¶

Receive raw serial data through vexlink.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.
EINVAL - The data given is NULL

uint32_t link_receive_raw(uint8_t port, void* dest, uint16_t data_size);

#define LINK_RECIVER_PORT 1

void opcontrol() {
  while (true) {
    char* result;
    char* expected = "Hello!";
    link_receive_raw(LINK_RECIVER_PORT, (void*)result, sizeof(*expected) * sizeof(expected));
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.
data	Buffer with data to send
data_size	Bytes of data to be read to the destination buffer

Returns: PROS_ERR if port is not a link, 0 if the link is busy, and 1 if it succeeded.

link_transmit ¶

Send packeted message through vexlink, with a checksum and start byte.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.
EBUSY - The transmitter buffer is still busy with a previous transmission, and there is no room in the FIFO buffer (queue) to transmit the data.
EINVAL - The data given is NULL

uint32_t link_transmit(uint8_t port, void* data, uint16_t data_size);

#define LINK_TRANSMITTER_PORT 1

void opcontrol() {
  while (true) {
    char* data = "Hello!";
    link_transmit(LINK_TRANSMITTER_PORT, (void*)data, sizeof(*data) * sizeof(data));
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.
data	Buffer with data to send
data_size	Bytes of data to be read to the destination buffer

Returns: PROS_ERR if port is not a link, 0 if the link is busy, and the successfully transmitted size if it succeeded.

link_receive ¶

Receive packeted message through vexlink, with a checksum and start byte.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.
EINVAL - The destination given is NULL, or the size given is larger than the FIFO buffer or destination buffer.
EBADMSG - Protocol error related to start byte, data size, or checksum.

uint32_t link_receive(uint8_t port, void* dest, uint16_t data_size);

#define LINK_RECIVER_PORT 1

void opcontrol() {
  while (true) {
    char* result;
    char* expected = "Hello!";
    link_receive(LINK_RECIVER_PORT, (void*)result, sizeof(*expected) * sizeof(expected));
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.
data	Buffer with data to send
data_size	Bytes of data to be read to the destination buffer

Returns: PROS_ERR if port is not a link or protocol error, 0 if the link is busy, and the successfully transmitted size if it succeeded.

link_clear_receive_buf ¶

Clear the receive buffer of the link, and discarding the data.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as a radio.
ENXIO - The sensor is still calibrating, or no link is connected via the radio.

uint32_t link_clear_receive_buf(uint8_t port);

#define LINK_TRANSMITTER_PORT 1

void opcontrol() {
  while (true) {
    char* data = "Hello!";
    link_transmit(LINK_TRANSMITTER_PORT, (void*)data, sizeof(*data) * sizeof(data));
    link_clear_receive_buf(LINK_TRANSMITTER_PORT);
    delay(20);
  }
}

Parameters
port	The port of the radio for the intended link.

Returns: PROS_ERR if port is not a link, 0 if the operation succeeded.

Enumerated Values ¶

typedef enum link_type_e {
  E_LINK_RECIEVER = 0,
  E_LINK_TRANSMITTER,
  E_LINK_RX = E_LINK_RECIEVER,
  E_LINK_TX = E_LINK_TRANSMITTER
} link_type_e_t;

Value
E_LINK_RECIEVER	Indicating that the radio is a reciever.
E_LINK_RX	Indicating that the radio is a reciever.
E_LINK_TRANSMITTER	Indicating that the radio is a transmitter.
E_LINK_TX	Indicating that the radio is a transmitter.