topic Re: M5213EVB I2C data I/O register problems in ColdFire/68K Microcontrollers and Processors

M5213EVB I2C data I/O register problems

jrowland — Thu, 27 Mar 2008 22:59:30 GMT

Hi everyone, I've just started messing with I2C and i seem to have run into a little problem, For some reason I cannot write to the I2DR register. I've used the driver example given by Dr Seuss with a change in I2C pins to :

/* I2C pins configuration */
MCF_GPIO_PASPAR |= ( MCF_GPIO_PASPAR_PASPAR0(0x01)

| MCF_GPIO_PASPAR_PASPAR1(0x01));

My next step was setting up the I2C for transmit because I needed to transmitt the id of the device like so:

uint8 I2CreceivedByte(uint8 address, uint8 id)
{
  int i;
  uint8 data;

  MCF_I2C_I2CR = 0xB0 ;  //enable I2C set to master transmit mode

MCF_I2C_I2DR = 0xC0; //set the id to the I/O register

I was watching the registers while running the program in debug mode. From what I observed the I2DR register never gets the id. I'm not exactly sure what is wrong however I feel like i'm missing something. The following is what my registers look like up to this line of code.

/*I2C Registers*/

I2ADR 0x00

I2FDR 0x32

I2CR 0xB0

I2SR 0x81

I2DR 0x00

/*General Purpose I/O Port AS Registers*/

PORTAS 0x03

DDRAS 0x00

SETAS 0x03

CLRAS 0x00

PASPAR 0x05

Thanks in advance for any helps or hints anyone can give me

Re: M5213EVB I2C data I/O register problems

jrowland — Sat, 29 Mar 2008 01:49:48 GMT

Looking at the sample code for the I2C module for the M5213EVB it turns out that I was using/initializing the wrong port. I turns out that I needed to use PORT QS correcting my initialization to :

/* I2C pins configuration */
MCF_GPIO_PQSPAR = 0 | ( MCF_GPIO_PQSPAR_PQSPAR3(2)

| MCF_GPIO_PQSPAR_PQSPAR2(2));

In doing this I am finally able to change the I2DR register value. What I don't understand is from looking at the MCF5213 Reference Manual it mentions that Port AS has SDA and SCL . Does this mean that both Port AS and Port QS have I2C SDA and SCL ports? If so, why could I not modifiy the I2DR register when setting the Port AS? Thanks in advance for any information that can help me clear up this confusion.

Message Edited by jrowland on 2008-03-28 06:50 PM

Re: M5213EVB I2C data I/O register problems

SimonMarsden_de — Mon, 31 Mar 2008 21:05:49 GMT

Hi

The I2C module can be connected to one of two different sets of physical pins (or not connected at all if you're not using it - you might need the pins for something else). The choice is made through the Pin Assignment registers.

Obviously you need to choose the mapping which matches how you've actually wired up the I2C port to the processor.

The reason that Pin Assignment Registers are needed is because there are more possible sources of signals from the processor modules (UARTs, timers, GPIO, I2C, etc, etc), than there are pins. It's not possible to use all of the modules on a ColdFire processor at the same time.

Hope this clears up the mystery

Simon