Function of Encoder AMT203

Functions
int	enc_read_pos (int spi_dev, unsigned short int *data)
	READ POSITION. More...
int	enc_zero_set (int spi_dev)
	SET ZERO POINT. More...
int	enc_wait_for_ack (int spi_dev, uint8_t ack, int max_errors)
	send command and delay between reads More...

Detailed Description

Function Documentation

int enc_read_pos	(	int	spi_dev,
		unsigned short int *	data
	)

READ POSITION.

Parameters

	spi_dev	Communication Port
[in]	*data	Data to read

Returns

flag with SUCCESS or FAILURE

Check this function, in case of error put delay before each byte data

Definition at line 37 of file encoder_functions.c.

References ARRAY_SIZE, enc_wait_for_ack(), ENCODER_NO_OP, ENCODER_RD_POS, FAILURE, INT_MAX, spi_trans_bytes(), and SUCCESS.

Referenced by read_all_data().

                                                      {

    uint8_t send[] = {ENCODER_RD_POS,ENCODER_NO_OP};
    uint8_t receive[ARRAY_SIZE(send)] = {0, };
    uint8_t buffer[ARRAY_SIZE(send)] = {0, } ;
    
    /* Send command */
    spi_trans_bytes(spi_dev,send,receive,1);
    if (enc_wait_for_ack(spi_dev, ENCODER_RD_POS, INT_MAX) != SUCCESS) { 
        return FAILURE; 
    }

    send[0]=ENCODER_NO_OP;

    if(spi_trans_bytes(spi_dev,send,receive,2) != SUCCESS) { 
        return FAILURE; 
    }

    buffer[0] = receive[0];

    if(spi_trans_bytes(spi_dev,send,receive,2) != SUCCESS) { 
        return FAILURE; 
    }

    buffer[1] = receive[0];

    *data = buffer[0]*256+buffer[1];

    //printf("\nreceive = 0x %2x %2x %d\n",buffer[0],buffer[1],data);

   return SUCCESS;
}

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int enc_wait_for_ack	(	int	spi_dev,
		uint8_t	ack,
		int	max_errors
	)

send command and delay between reads

Parameters

	spi_dev	Communication Dev
[in]	data	Data to write

Returns

flag with SUCCESS or FAILURE

Definition at line 73 of file encoder_functions.c.

References ENCODER_NO_OP, ENCODER_WAIT_RESP, FAILURE, spi_trans_bytes(), and SUCCESS.

Referenced by enc_read_pos(), and enc_zero_set().

{
    int errors = 0;
    uint8_t send = ENCODER_NO_OP;
    uint8_t receive = 1;
        
  //nanosleep(10);
        //spi_trans_bytes(spi_dev,send,receive,1);
    while (receive != ack) {
        spi_trans_bytes(spi_dev,&send,&receive,1);
        //printf("\nReceive = 0x%x \n",receive);
        if (receive != ENCODER_WAIT_RESP) {
            errors++;
            if (errors > max_errors) { return FAILURE; }
        }
    }


    return SUCCESS;
}

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int enc_zero_set

(

int

spi_dev

)

SET ZERO POINT.

Parameters

	spi_dev	Communication Dev
[in]	data	Data to write

Returns

flag with SUCCESS or FAILURE

Definition at line 19 of file encoder_functions.c.

References enc_wait_for_ack(), ENCODER_EEPROM_WR, ENCODER_SET_ZERO_PT, FAILURE, INT_MAX, spi_trans_bytes(), and SUCCESS.

                             {

    uint8_t send = ENCODER_SET_ZERO_PT;
    uint8_t receive = 0;
    
    /* Send command */
    spi_trans_bytes(spi_dev,&send,&receive,1);
    if (enc_wait_for_ack(spi_dev, ENCODER_EEPROM_WR, INT_MAX) != SUCCESS){ 
        return FAILURE;
    }

    /* Note: 
     *   From datasheet, the encoder must be power-cycled after this command
     *   for the new zero position to be used in the position calculation. */

    return SUCCESS;
}

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