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PIC18F2685 I2C LMP91000

 
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towerspower



Joined: 11 Jun 2017
Posts: 1

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PIC18F2685 I2C LMP91000
PostPosted: Sun Jun 11, 2017 5:27 am     Reply with quote
Hello!

I'm trying to communicate the PIC18F2685 with the LMP91000 by I2C but i'm having some problems. Here it is the code i'm writting.

Code:
#use i2c(Master, SDA=PIN_C4, SCL=PIN_C3, FAST=100000)

#define POT_SLAVE_WRT  0xD0
#define POT_SLAVE_RD   0xD1

// Register addresses
#define STATUS     0x00
#define LOCK       0x01
#define TIACN      0x10
#define REFCN      0x11
#define MODECN     0x12

void SETUP ()
{
   
   i2c_start();
   i2c_write(POT_SLAVE_WRT);
   i2c_write(LOCK);
   i2c_write(0x00);
   i2c_stop();
   
   i2c_start();
   i2c_write(POT_SLAVE_WRT);
   i2c_write(TIACN);
   i2c_write(0x1F);
   i2c_stop();

   i2c_start();
   i2c_write(POT_SLAVE_WRT);
   i2c_write(REFCN);
   i2c_write(0x54);
   i2c_stop();

   i2c_start();
   i2c_write(POT_SLAVE_WRT);
   i2c_write(MODECN);
   i2c_write(0x03);
   i2c_stop();
 
   i2c_start();
   i2c_write(POT_SLAVE_WRT);
   i2c_write(LOCK);
   i2c_write(0x01);
   i2c_stop();
   
}
 

void main ()
{
   SETUP();
   while(true)
   {
output_toggle(pin_A0);  //this part of the code is just to know if the PIC works . It does.
delay_ms(500);

   }
}

I've already checked that i have put the pull up resistors and all the connections are okey, but i can't write on the LMP91000 registers becuse of the i2c problem. Do you have any answer to my problem? Thank you very much!!
Ttelmah



Joined: 11 Mar 2010
Posts: 19539

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PostPosted: Sun Jun 11, 2017 8:23 am     Reply with quote
Before doing anything else, run the I2C scanner program (in the code library), and verify that your chip is being 'seen' by your PIC at the addresses specified.

This is the first thing to do before looking at your code. Smile

Your address does not appear to be right. The bus address of the standard 91000, is 0x90 for write, and 0x91 for read. You are using 0xD0/D1. Unless you have a non standard chip, this may be your problem.

Just checked the data sheet. Section 7.5.1. The address is 0x90/91.

Binary 10010000 for write
10010001 for read

This is almost certainly what is stopping it from working....
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