firmata.h File Reference

API Description

Firmata IO lets you SYSEX messages construct and ask for a callback on a SYSEX messages. This is meant to provide a way to call custom firmata APIs especially using the Custom firmata API

    mraa_add_subplatform(MRAA_GENERIC_FIRMATA, "/dev/ttyACM0");
    mraa_firmata_context firm = mraa_firmata_init(FIRMATA_CURIE_IMU);
    if (firm == NULL) {
        return EXIT_FAILURE;
    }

    mraa_firmata_response(firm, interrupt);

    char* buffer = calloc(4, 0);
    if (buffer == NULL) {
        free(firm);
        return EXIT_FAILURE;
    }
    buffer[0] = FIRMATA_START_SYSEX;
    buffer[1] = FIRMATA_CURIE_IMU;
    buffer[2] = FIRMATA_CURIE_IMU_READ_ACCEL;
    buffer[3] = FIRMATA_END_SYSEX;

    mraa_firmata_write_sysex(firm, buffer, 4);

    sleep(1);

    // stop the isr and set it again
    mraa_firmata_response_stop(firm);
    mraa_firmata_response(firm, interrupt);
    mraa_firmata_write_sysex(firm, buffer, 4);

    sleep(1);

    // close everything and try again
    mraa_firmata_close(firm);
    firm = mraa_firmata_init(FIRMATA_CURIE_IMU);
    mraa_firmata_response(firm, interrupt);
    mraa_firmata_write_sysex(firm, buffer, 4);

    sleep(10);

    mraa_firmata_close(firm);

Go to the source code of this file.

Functions
mraa_firmata_context	mraa_firmata_init (int feature)
mraa_result_t	mraa_firmata_write_sysex (mraa_firmata_context dev, char *msg, int length)
mraa_result_t	mraa_firmata_response (mraa_firmata_context dev, void(*fptr)(uint8_t *, int))
mraa_result_t	mraa_firmata_response_stop (mraa_firmata_context dev)
mraa_result_t	mraa_firmata_close (mraa_firmata_context dev)

Typedefs
typedef struct _firmata *	mraa_firmata_context

Function Documentation

mraa_firmata_context mraa_firmata_init

(

int

feature

)

Initialise firmata context on a feature. This feature is what will be listened on if you request a response callback

Parameters

feature

firmata feature

Returns

firmata context or NULL

mraa_result_t mraa_firmata_write_sysex	(	mraa_firmata_context	dev,
		char *	msg,
		int	length
	)

Sends a custom SYSEX message to the firmata board.

Parameters

dev	The Firmata context
msg	The SYSEX message
length	The length of the sysex message

mraa_result_t mraa_firmata_response	(	mraa_firmata_context	dev,
		void(*)(uint8_t *, int)	fptr
	)

Set a callback on 'feature'. This function is not thread safe and threads calling it need to make sure they are the only thread calling this.

Parameters

dev	The Firmata context
fptr	Function pointer to function to be called when interrupt is triggered, the returned buffer and length are the arguments.

Returns

Result of operation

mraa_result_t mraa_firmata_response_stop

(

mraa_firmata_context

dev

)

Stop getting events on feature. This is more efficient than mraa_firmata_close as it can be re-enabled without adding a feature

Parameters

dev	The Firmata context

Returns

Result of operation

mraa_result_t mraa_firmata_close

(

mraa_firmata_context

dev

)

Free all firmata handle resources, this will leave an element in an array internally that will be skipped, avoid closing many firmata contexts often as there is a cost to doing this

Parameters

dev	The Firmata context

Returns

Result of operation

Typedef Documentation

typedef struct _firmata* mraa_firmata_context

Opaque pointer definition to the internal struct _firmata. This context refers to one firmata 'extension' letting you write/return SYSEX messages directly

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