DE10 Nano Kit - I2C

1

Greetings,

I’m using a DE10 Nano kit SoC FPGA and would like to read a temperature sensor from the HPS via I2C. I connected the sensor to 3.3V, GND and two 2 pins on the board. I’m using the following C code (which is not mine):

// Distributed with a free-will license.
// Use it any way you want, profit or free, provided it fits in the licenses of its associated works.
// TMP100
// This code is designed to work with the TMP100_I2CS I2C Mini Module available from ControlEverything.com.
// https://www.controleverything.com/content/Temperature?sku=TMP100_I2CS#tabs-0-product_tabset-2

#include <stdio.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <fcntl.h>

void main()
{
// Create I2C bus
int file;
char *bus = “/dev/i2c-1”;
if ((file = open(bus, O_RDWR)) < 0)
{
printf(“Failed to open the bus. \n”);
exit(1);
}
// Get I2C device, TMP100 I2C address is 0x4F(79)
ioctl(file, I2C_SLAVE, 0x4F);

// Select configuration register(0x01)
// Continuous conversion, comparator mode, 12-bit resolution(0x60)
char config[2] = {0};
config[0] = 0x01;
config[1] = 0x60;
write(file, config, 2);
sleep(1);

// Read 2 bytes of data from register(0x00)
// temp msb, temp lsb
char reg[1] = {0x00};
write(file, reg, 1);
char data[2] = {0};
if(read(file, data, 2) != 2)
{
	printf("Error : Input/Output error \n");
}
else
{
	// Convert the data to 12-bits
	int temp = (data[0] * 256 + (data[1] & 0xF0)) / 16;
	if(temp > 2047)
	{
		temp -= 4096;
	}
	float cTemp = temp * 0.0625;
	float fTemp = cTemp * 1.8 + 32;

	// Output data to screen
	printf("Temperature in Celsius is : %.2f C \n", cTemp);
	printf("Temperature in Fahrenheit is : %.2f F \n", fTemp);
}

}

I can’t read any value. Sometimes the read value is null, sometimes I get an error opening the file for reading.
What am I missing?

Thanks in advance!