I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Wed, 03 May 2017 09:35:15 GMT

If you get non-zero return values from the I2C functions, that means the slave isn't responding. So it's probably a configuration issue.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Wed, 03 May 2017 09:34:40 GMT

I honestly don't think there is a reason to think there's a fault in the I2C implementation. Can you post your application code? Also, is there a specific reason you're using SoftI2C instead of just the I2C mbed class?

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Wed, 03 May 2017 05:44:40 GMT

This is the cpp file of i2c in mbed

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Wed, 03 May 2017 05:43:54 GMT

#include "SoftI2C.h"

SoftI2C::SoftI2C(PinName sda, PinName scl) : _sda(sda), _scl(scl) { // Set defaults _sda.mode(PullNone); _scl.mode(PullNone); _sda.input(); _scl.input(); frequency(100000);

active = false;

}

void SoftI2C::frequency(int hz) { delay_us = 1000000 / hz / 4; //delay is a quarter of the total period }

int SoftI2C::read(int address, char *data, int length, bool repeated) { start();

// Write address with LSB to one
if (write(address | 0x01) == 0) {
    return 1;
}  

// Read the data
for(int i = 0; i<length - 1; i++) {
    data[i] = read(1);
}
data[length-1] = read(0);

if (repeated == false) {
    stop();
}
return 0;

}

int SoftI2C::write(int address, const char *data, int length, bool repeated) { start();

// Write address with LSB to zero
if (write(address & 0xFE) == 0) {
    return 1;
}  

// Write the data
for(int i = 0; i<length; i++) {
    if(write(data[i]) == 0) {
        return 1;
    }
}

if (repeated == false) {
    stop();
}
return 0;

}

int SoftI2C::read(int ack) { int retval = 0; _scl.output();

// Shift the bits out, msb first
for (int i = 7; i>=0; i--) {
    //SCL low
    _scl.write(0);
    _sda.input();
    wait_us(delay_us);
    
    //read SDA
    retval |= _sda.read() << i;
    wait_us(delay_us);
    
    //SCL high again
    _scl.write(1);
    wait_us(delay_us << 1); //wait two delays
}

// Last cycle to set the ACK
_scl.write(0);
if ( ack ) {
    _sda.output();
    _sda.write(0);
} else {
    _sda.input();
}
wait_us(delay_us << 1);

_scl.write(1);
wait_us(delay_us << 1);


return retval;

}

int SoftI2C::write(int data) { _scl.output();

// Shift the bits out, msb first
for (int i = 7; i>=0; i--) {
    //SCL low
    _scl.write(0);
    wait_us(delay_us);
    
    //Change SDA depending on the bit
    if ( (data >> i) & 0x01 ) {
        _sda.input();
    } else {
        _sda.output();
        _sda.write(0);
    }
    wait_us(delay_us);
    
    //SCL high again
    _scl.write(1);
    wait_us(delay_us << 1); //wait two delays
}

// Last cycle to get the ACK
_scl.write(0);
wait_us(delay_us);

_sda.input();
wait_us(delay_us);

_scl.write(1);
wait_us(delay_us);
int retval = ~_sda.read(); //Read the ack
wait_us(delay_us);

return retval;

}

void SoftI2C::start(void) { if (active) { //if repeated start //Set SDA high, toggle scl _sda.input(); _scl.output(); _scl.write(0); wait_us(delay_us << 1); _scl.write(1); wait_us(delay_us << 1); } // Pull SDA low _sda.output(); _sda.write(0); wait_us(delay_us); active = true; }

void SoftI2C::stop(void) { // Float SDA high _scl.output(); _scl.write(0); _sda.output(); _sda.write(0); wait_us(delay_us); _scl.input(); wait_us(delay_us); _sda.input(); wait_us(delay_us);

active = false;

}

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Wed, 03 May 2017 05:34:25 GMT

int err = 1 when i print err_code

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Sat, 29 Apr 2017 09:04:55 GMT

Check out the updated answer. And just to clarify, you have this line somewhere in your code: I2C i2c(P0_10, P0_8); // SDA, SCL? Can you post your whole code example?

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 21:57:36 GMT

I am sorry I dont understand this question, please explain?

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Fri, 28 Apr 2017 21:54:40 GMT

what is the value returned if you set int err = i2c.write(...) on the first write operation?

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 21:46:38 GMT

yes for blenano I use D2, D3

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Fri, 28 Apr 2017 21:44:25 GMT

Are you initializing the I2C controller correctly using mbed? I.e. using I2C i2c(SDA_PIN, SCL_PIN)?

See example here: developer.mbed.org/.../

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 21:31:05 GMT

The value now I get is 54919680

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 21:25:20 GMT

I wrote through blenano and I checked the value stored in eeprom usign other controller. Seenms like it is not writing on the eeprom as the value is not changing.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Fri, 28 Apr 2017 20:48:32 GMT

Try removing the i2c.start() line. From the mbed I2C documentation that function generates a start condition on the bus, which i2c.read() and i2c.write() should do automatically.

Also, can you check the output of both i2c.read() and i2c.write() and see if they're some other value than 0? They return integer result codes according to mbed documentation.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 18:12:30 GMT

i tried your code but still getting -1

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 18:10:35 GMT

I am using mbed compiler i2c driver

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Fri, 28 Apr 2017 17:54:40 GMT

Please see the updated answer.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 17:50:42 GMT

it works fine with LPC M4-cortex microcontroller.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 16:08:22 GMT

please tell me how should i change it.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 15:37:53 GMT

I AM USING 24LC256 BY MICROCHIP

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

dingari — Fri, 28 Apr 2017 09:24:13 GMT

For the first thing, have you tried reading the response array and check what the bytes contain? I'm guessing they're all 255.

Also, this part doesn't do what the comment says:

//READ //Setting read pointer to 0 value = 0; data[0] = 0; // MSB address data[1] = 0; // LSB address

i2c.write(0xA0, data, 2);

I have no idea what device you're communicating with, but when you call i2c.write(0xA0, data, 2), your array is still data[0] = 0, data[1] = 3 and data[2] = 159 from the previous command.

Edit 2017-04-28:

Are you sure your i2c.read() function requires you to add the read bit to the address (0xA0+1)? I don't know what I2C driver you're using, but I'd think the function would be implemented in such a manner that you'd just pass the device address (0xA0) and it automatically adds the read bit.

Try this (untested):

uint32_t value = 99999;

lcd.clear(); 
lcd.setPosition(0,1); 
lcd.printf("Writing bytes 0-16\n");

data[0] = 0; 
data[1] = 0;
data[2] = ((value >> 24) & 0xFF); 
int err_code = i2c.write(0xA0, data, 3);
wait(0.1);
if(err_code != 0) {
	lcd.clear(); 
	lcd.setPosition(0,0); 
	lcd.printf("I2C write error: %d", err_code);
	wait(5);
}

data[0] = 0; 
data[1] = 1; 
data[2] = ((value >> 16) & 0xFF); 
i2c.write(0xA0, data, 3); 
wait(0.1);

data[0] = 0; 
data[1] = 2; 
data[2] = ((value >> 8) & 0xFF); 
i2c.write(0xA0, data, 3); 
wait(0.1);

data[0] = 0; 
data[1] = 3; 
data[2] = (value & 0xFF); 
i2c.write(0xA0, data, 3); 
wait(0.1);

// Read from address 0
data[0] = 0; // MSB address 
data[1] = 0; // LSB address
i2c.write(0xA0, data, 2);

char response[4]; 
i2c.read(0xA0, response, 4);
value = (response[0]<<24) | (response[1]<<16) | (response[2]<<8) | response[3];

lcd.clear(); 
lcd.setPosition(0,0); 
lcd.printf("%d", value); 
wait(5);

And please try to refrain from multiple statements per line. It makes the code very hard to read.

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

jay — Fri, 28 Apr 2017 03:34:49 GMT

it says my i2c function doesnt support it. It needs a char function

RE: I am getting -1 on the screen when I save an unint32 and read it back? I am using BLEnano

SAM.MAO — Fri, 28 Apr 2017 03:25:27 GMT

Also you can have a try to change to " value = response[0] * 16777216 + response[1] * 65536 + response[2] * 256 + response[3];"