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LPC4088 with LM75 temperature sensor

Hello all,

I'm using LPC4088 experiment bundle, in which a temperature sensor (LM75) is connected to the LPC4088 controller using IC2 connection.
I'm using this code to test the temperature sensor. However, the program is getting stuck at temperature_enable(); The code changes an RGB LED color based on the temperature value.

This is the main code
#include <stdint.h>
#include <stdio.h>
#include "leds.h"
#include "temperature.h"

const int threshold[] = {29, 28, 27, 26, 25, 24};
const int colors[][3] = { { 1, 1, 1}, // White { 1, 0, 1}, // Magenta { 1, 0, 0}, // Red { 1, 1, 0}, // Yellow { 0, 0, 1}, // Blue { 0, 1, 0} // Green
};

void pick_leds(float measured) { int i; for (i = 0; i < sizeof(threshold) / sizeof(int); i++) { if (measured >= threshold[i]) { break; } } leds_set(colors[i][0], colors[i][1], colors[i][2]);
}

int main(void) { leds_init();
temperature_init();
temperature_enable(); __enable_irq();

while (1) {
pick_leds(temperature_read()); //pick_leds(29); }
}

This is the temperature.c
#include "temperature.h"
#include "i2c.h"

#define SLAVE_ADDRESS 0x90
#define READ 0x1
#define WRITE 0x0
#define START_CONVERT_T 0x51
#define READ_TEMPERATURE 0xAA

void temperature_init(void) { i2c_init();
}

void temperature_enable(void) { uint8_t buff[1]; buff[0] = START_CONVERT_T; i2c_write(SLAVE_ADDRESS, buff, 1);
}

float temperature_read(void) { short temp; uint8_t buff[2]; buff[0] = READ_TEMPERATURE; i2c_write(SLAVE_ADDRESS, buff, 1); i2c_read(SLAVE_ADDRESS, buff, 2); temp = (buff[0] << 8) | buff[1];

// Sign extend from 16-bit to 12-bit. temp >>= 4;

// Convert from fixed point to floating point. return temp / (float)16;
}

0 Zack Win over 8 years ago
Hello Lilas,

What part of temperature_enable() does the code stop executing?

When it gets stuck, does it stay on a particular line?
If you enter debug mode, and go to Peripherals => Core Peripherals => Fault Reports, does any checkmark appear in this dialog when the function executes?

In the future, try placing source code between:

< pre > and < /pre >

tags. See: http://www.keil.com/forum/tips.asp

Thanks,
Zack
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0 Lilas Alrahis over 8 years ago in reply to Zack Win

Thank you Zack for the tip!
It gets stuck at

i2c_write(SLAVE_ADDRESS, buff, 1);

Inside that function (in the i2c library) we have:

void i2c_write(uint8_t address, uint8_t *buffer, int buff_len) {
        uint32_t i = 0;
        LPC_I2C0->CONSET |= 0x20;
        start:  switch(LPC_I2C0->STAT)
        {
                case I2C_I2STAT_M_TX_START:
                case I2C_I2STAT_M_TX_RESTART:
                        LPC_I2C0->DAT = address | WRITE;
                        I2C_Mode_Clr(Y,0,0,Y);
                        goto start;

                case I2C_I2STAT_M_TX_SLAW_ACK:
                        LPC_I2C0->DAT = buffer[i];
                        I2C_Mode_Clr(0,0,0,Y);
                                i++;
                        goto start;

                case I2C_I2STAT_M_TX_SLAW_NACK:;
                        I2C_Mode_Set(1,1,X,X);
                        I2C_Mode_Clr(Y,Y,0,Y);
                        goto start;

                case I2C_I2STAT_M_TX_DAT_ACK:
                        if(i <= buff_len -1){
                  LPC_I2C0->DAT = buffer[i];
                        I2C_Mode_Clr(0,0,0,Y);
                                i++;
                        goto start;
                        }
                        else{
                        I2C_Mode_Set(1,X,X,X);
                        I2C_Mode_Clr(Y,0,0,Y);
                        break;
                        }

                case I2C_I2STAT_M_TX_DAT_NACK:
                        I2C_Mode_Set(1,X,X,X);
                        I2C_Mode_Clr(Y,Y,0,Y);
                break;

                case I2C_I2STAT_M_TX_ARB_LOST:
                        I2C_Mode_Set(1,X,X,X);
                        I2C_Mode_Clr(Y,0,0,Y);
                  goto start;

                case I2C_I2STAT_M_BUS_ERROR:
                        I2C_Mode_Set(X,1,X,X);
                        I2C_Mode_Clr(0,Y,0,Y);
                        LPC_I2C0->CONSET |= 0x20;
      goto start;

                default:
                        goto start;;
        }

        // Send the following sequence:
        //  - Start bit
        //  - Contents of buffer, from 0..buff_len
        //  - Stop bit
}

It is getting stuck at the second case (restart)
Im new to the controller and the Keil environment. Could the slave address be wrong?