AT (Hayes) command set library

AT (Hayes) command set library.

This module provides functions to interact with devices using AT commands.

Most functions compare the bytes echoed by the device with what they intended to send, and bail out if there’s no match.

Furthermore, the library tries to cope with difficulties regarding different line endings. It usually sends “<command><CR>”, but expects “<command>\LF\CR” as echo.

As a debugging aid, when compiled with “-DAT_PRINT_INCOMING=1”, every input byte gets printed.

void(* at_urc_cb_t()

Unsolicited result code callback.

Parameters

arg:optional argument
code:urc string received from the device

int at_dev_init(at_dev_t * dev, uart.h::uart_t uart, uint32_t baudrate, char * buf, msp430_types.h::size_t bufsize)

Initialize AT device struct.

Parameters

dev:struct to initialize
uart:UART the device is connected to
baudrate:baudrate of the device
buf:input buffer
bufsize:size of buf

Return values

  • 0 on success
  • <0 otherwise
int at_send_cmd_wait_ok(at_dev_t * dev, const char * command, uint32_t timeout)

Simple command helper.

This function sends an AT command to the device and waits for “OK”.

Parameters

dev:device to operate on
command:command string to send
timeout:timeout (in usec)

Return values

  • 0 when device answers “OK”
  • <0 otherwise
int at_send_cmd_wait_prompt(at_dev_t * dev, const char * command, uint32_t timeout)

Send AT command, wait for a prompt.

This function sends the supplied command, then waits for the prompt (>) character and returns

Parameters

dev:device to operate on
command:command string to send
timeout:timeout (in usec)

Return values

  • 0 when prompt is received
  • <0 otherwise
msp430_types.h::ssize_t at_send_cmd_get_resp(at_dev_t * dev, const char * command, char * resp_buf, msp430_types.h::size_t len, uint32_t timeout)

Send AT command, wait for response.

This function sends the supplied command, then waits and returns one line of response.

A possible empty line will be skipped.

Parameters

dev:device to operate on
command:command to send
resp_buf:buffer for storing response
len:len of buffer
timeout:timeout (in usec)

Return values

  • length of response on success
  • <0 on error
msp430_types.h::ssize_t at_send_cmd_get_lines(at_dev_t * dev, const char * command, char * resp_buf, msp430_types.h::size_t len, bool keep_eol, uint32_t timeout)

Send AT command, wait for multiline response.

This function sends the supplied command, then returns all response lines until the device sends “OK”.

If a line starts with “ERROR” or “+CME ERROR:”, or the buffer is full, the function returns -1.

Parameters

dev:device to operate on
command:command to send
resp_buf:buffer for storing response
len:len of resp_buf
keep_eol:true to keep the CR character in the response
timeout:timeout (in usec)

Return values

  • length of response on success
  • <0 on error
int at_expect_bytes(at_dev_t * dev, const char * bytes, uint32_t timeout)

Expect bytes from device.

Parameters

dev:device to operate on
bytes:buffer containing bytes to expect (NULL-terminated)
timeout:timeout (in usec)

Return values

  • 0 on success
  • <0 otherwise
void at_send_bytes(at_dev_t * dev, const char * bytes, msp430_types.h::size_t len)

Send raw bytes to a device.

Parameters

dev:device to operate on
bytes:buffer containing bytes to send
len:number of bytes to send

int at_send_cmd(at_dev_t * dev, const char * command, uint32_t timeout)

Send command to device.

Parameters

dev:device to operate on
command:command to send
timeout:timeout (in usec)

Return values

  • 0 on success
  • <0 otherwise
msp430_types.h::ssize_t at_readline(at_dev_t * dev, char * resp_buf, msp430_types.h::size_t len, bool keep_eol, uint32_t timeout)

Read a line from device.

Parameters

dev:device to operate on
resp_buf:buffer to store line
len:size of resp_buf
keep_eol:true to keep the CR character in the response
timeout:timeout (in usec)

Return values

  • line length on success
  • <0 on error
void at_drain(at_dev_t * dev)

Drain device input buffer.

This function drains any possible bytes waiting in the device’s input buffer.

Parameters

dev:device to operate on

void at_dev_poweron(at_dev_t * dev)

Power device on.

Parameters

dev:device to power on

void at_dev_poweroff(at_dev_t * dev)

Power device off.

Parameters

dev:device to power off

void at_add_urc(at_dev_t * dev, at_urc_t * urc)

Add a callback for an unsolicited response code.

Parameters

dev:device to operate on
urc:unsolicited result code to register

void at_remove_urc(at_dev_t * dev, at_urc_t * urc)

Remove an unsolicited response code from the list.

Parameters

dev:device to operate on
urc:unsolicited result code to remove

void at_process_urc(at_dev_t * dev, uint32_t timeout)

Process out-of-band data received from the device.

Parameters

dev:device to operate on
timeout:timeout (in usec)

AT_SEND_EOL

End of line character to send after the AT command. 

1
"\r"
AT_SEND_ECHO

Enable/disable the expected echo after an AT command is sent. 

1
1
AT_SEND_EOL_LEN

Shortcut for getting send end of line length. 

1
(sizeof(AT_SEND_EOL) - 1)
AT_RECV_EOL_1

1st end of line character received (S3 aka CR character for a modem) 

1
"\r"
AT_RECV_EOL_2

1st end of line character received (S4 aka LF character for a modem) 

1
"\n"
AT_RECV_OK

default OK reply of an AT device 

1
"OK"
AT_RECV_ERROR

default ERROR reply of an AT device 

1
"ERROR"
AT_BUF_SIZE

Internal buffer size used to process unsolicited result code data. 

1
(128)
struct at_urc_t

Unsolicited result code data structure.

clist.h::clist_node_t list_node

node list

at.h::at_urc_cb_t cb

callback

const char * code

URC string which must match.

void * arg

optional argument

struct at_dev_t

AT device structure.

isrpipe_t isrpipe

isrpipe used for getting data from uart

uart.h::uart_t uart

UART device where the AT device is attached.