scpi_parser/README.md

SCPI parser

This library provides a simple ("KISS") SCPI implementation for embedded devices (instruments).

The implementation is not 100% complete, but it's sufficient for basic SCPI communication.

What's supported

• The hierarchical header model (commands with colon)
• Long and short header variants (eg. SYSTem?)
• Easy configuration with one const array of structs and callback functions (see main.c)
• Semicolon for chaining commands on the same level
• String, Int, Float, Bool arguments
• Block data argument with callback each N received bytes (configurable)
• Status Register model
• Error queue including error messages from the SCPI spec
• All mandatory SCPI commands (headers) are implemented as built-ins

Built-in commands can be overriden in user command array.

How to use

See main.c for example of how to use the library.

Here's an overview of stubs you have to implement (at the time of writing this readme):

#include "scpi_parser.h"

// Receive byte - call:
//   scpi_handle_byte()
//   scpi_handle_string()


// ---- DEVICE IMPLEMENTATION ----

const SCPI_error_desc scpi_user_errors[] = {
	{10, "Custom error"}, // add your custom errors here (positive numbers)
	{/*END*/} // <-- end marker
};


void scpi_send_byte_impl(uint8_t b)
{
	// send the byte to master (over UART?)
}


const char *scpi_device_identifier(void)
{
	// fill in your device info
	// possible to eg. read a serial # from EEPROM
	return "<manufacturer>,<product>,<serial#>,<version>";
}


/* Custom commands */
const SCPI_command_t scpi_commands[] = {
	// see the struct definition for more details. Examples:
	{
		.levels = {"APPLy", "SINe"},
		.params = {SCPI_DT_INT, SCPI_DT_FLOAT, SCPI_DT_FLOAT},
		.callback = cmd_APPL_SIN_cb
	},
	{
		.levels = {"DATA", "BLOB"},
		.params = {SCPI_DT_BLOB},
		.callback = cmd_DATA_BLOB_cb, // <-- command callback
		.blob_chunk = 4,
		.blob_callback = cmd_DATA_BLOB_data // <-- data callback
	},
	{/*END*/} // <-- important! Marks end of the array
};

// ---- OPTIONAL CALLBACKS ----

void scpi_service_request_impl(void)
{
	// Called when the SRQ flag in Status Byte is set.
	// Device should somehow send the request to master.
}

// Device specific implementation of common commands
// (status registers etc are handled internally)
void scpi_user_CLS(void) { /*...*/ }
void scpi_user_RST(void) { /*...*/ }
void scpi_user_TSTq(void) { /*...*/ }

See the header files for more info.

What is missing

• Number units and metric suffixes (k,M,G,m,u,n)
• DEF, MIN, MAX, INF, NINF argument values for numbers

Support for units and "constants" (DEF etc) in numeric fields will need some larger changes to the numeric parser and SCPI_argval_t.

Feel free to propose a pull request implementing any missing features.