12.1.3 Subroutine I2C_w_2_r_1

void I2C_w_2_r_1 (unsigned char addr, unsigned char com)

{

unsigned char var;

OpenI2C (MASTER, SLEW_ON);

SSPADD

= 0x27;

StartI2C ();

IdleI2C ();

var = WriteI2C(addr);

if (var ==

0) read_s++;

if (var == -1) read_c++;

if (var == -2) read_ac++;

if (var

<

0) goto stop;

var = WriteI2C(com);

if (var ==

0) read_s++;

if (var == -1) read_c++;

if (var == -2) read_ac++;

if (var

<

0) goto stop;

RestartI2C ();

// generates I2C bus restart condition

IdleI2C ();

var = WriteI2C(addr+1);

if (var ==

0) read_s++;

if (var == -1) read_c++;

if (var == -2) read_ac++;

if (var

<

0) goto stop;

Content = 0;

Content = ReadI2C ();

SSPCON2bits.ACKDT = 1;

// No master Acknowledge to terminate sequence

SSPCON2bits.ACKEN = 1;

// sending No Acknowledge bit

PIR1bits.SSPIF = 0;

while (SSPCON2bits.ACKEN == 1);

PIR1bits.SSPIF = 0;

// waiting till NA causes interrupt

stop:

StopI2C ();

CloseI2C ();

}

12.2 Operating the PS

Below is a small C-code for the main program to operate the proximity sensor of the SFH 7773.

The two subroutines, I2C_w_3 and I2C_w2_r1 are the same as above (see Sec. 12.1.2 and

12.1.3).

C-code for main program:

sfh_address = 0x38;

// address of SFH 7773

I2C_w_3 (sfh_address*2, 0x81, 0x03);

// initialize PS of the SFH 7773

I2C_w_3 (sfh_address*2, 0x82, 0x1E);

// set PS LED current to 200 mA

I2C_w_2_r_1 (sfh_address*2, 0x8F);

// read data byte of PS, register 0x8F

PS

=

Content;

12.3 Operating the ALS and PS in Interrupt Mode

The small C-code below operates the SFH 7773 in the interrupt mode. The ALS and PS are in

free-running mode. The interrupt event can occur through an ALS or PS event. The limits for

ALS (LB_LL, HB_LL, LB_HL, HB_HL) and PS (Prox_Limit) are set within the program.

After the interrupt has triggered the microcontroller the relevant sensor is determined and the

ALS or PS value is read out.

December 12, 2011

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