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Update code for PCF8591 usage

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Sanchayan Maity 2017-04-24 17:46:30 +05:30
parent 50e222e148
commit 82cc507e07
1 changed files with 62 additions and 27 deletions
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89
pcf8591/pcf8591.c
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@ -11,58 +11,93 @@
#define PCF8591_ADDRESS 0x48 #define PCF8591_ADDRESS 0x48
int main( int argc, char **argv ) int main(int argc, char **argv)
{ {
uint8_t i;
uint32_t fd; uint32_t fd;
uint32_t ret; uint32_t ret;
uint8_t command[2]; uint32_t adc_channel = 0;
uint8_t value[4]; uint32_t dac_output = 0;
useconds_t delay = 2000; uint8_t command[2] = {0};
uint8_t value[4] = {0};
useconds_t delay = 5000;
char *dev = "/dev/i2c-0"; char *dev = "/dev/i2c-0";
printf("PCF8591 ADC and DAC test code\n"); printf("PCF8591 ADC and DAC test code\n");
fd = open(dev, O_RDWR); fd = open(dev, O_RDWR);
if(fd < 0) { if (fd < 0) {
perror("Opening i2c device node\n"); perror("Opening i2c device node\n");
return 1; return -1;
} }
ret = ioctl(fd, I2C_SLAVE, PCF8591_ADDRESS); ret = ioctl(fd, I2C_SLAVE, PCF8591_ADDRESS);
if(ret < 0) { if (ret < 0) {
perror("Selecting i2c device\n"); perror("Selecting i2c device\n");
close (fd);
return -1;
} }
while (true) { while (true) {
for(i = 0; i < 4; i++) { printf("\n1. ADC 2. DAC 3. Exit\n");
scanf("%d", &adc_channel);
switch (adc_channel) {
case 1:
printf("\nEnter ADC channel number 0-3:\t");
scanf("%d", &adc_channel);
if ((adc_channel >= 0) && (adc_channel <= 3)) {
/*
* Analog output enable | Read Input i
* See Page 6 of NXP PCF8591 data sheet
*/
command[0] = 0x40 | ((adc_channel) & 0x03); /* Control Byte */
command[1] = dac_output; /* DAC Data Register */
/* ret = write(fd, &command, 2);
* Analog output enable | Read Input i if (ret != 2) {
* See Page 6 of NXP PCF8591 data sheet perror("i2c write failed");
*/ continue;
command[0] = 0x40 | ((i + 1) & 0x03); /* Control Byte */ }
command[1]++; /* DAC Data Register */
usleep(delay);
ret = read(fd, &value[0], 1);
if(ret != 1) {
perror("i2c read failed");
continue;
}
printf("\nADC Channel %d: value: %d\n", adc_channel, value[0]);
} else {
printf("Invalid ADC channel number\n");
}
break;
case 2:
printf("Enter DAC value:\t");
scanf("%d", &dac_output);
command[0] = 0x40 | ((adc_channel) & 0x03); /* Control Byte */
command[1] = dac_output & 0xff; /* DAC Data Register */
ret = write(fd, &command, 2); ret = write(fd, &command, 2);
if (ret != 2) if (ret != 2) {
perror("writing i2c device"); perror("i2c write failed");
continue;
usleep(delay); }
/* the read is always one step behind the selected input */
ret = read(fd, &value[i], 1);
if(ret != 1)
perror("reading i2c device");
usleep(delay); usleep(delay);
break;
case 3:
goto exit;
break;
default:
printf("Invalid input\n");
break;
} }
printf("0x%02x 0x%02x 0x%02x 0x%02x\n", value[0], value[1], value[2], value[3]);
sleep(1);
} }
exit:
close(fd); close(fd);
return(0); return(0);
} }