topic Re: Kinetis KL25z I2C basic configuration in Kinetis Microcontrollers

Kinetis KL25z I2C basic configuration

us1 — Fri, 22 Apr 2016 11:43:32 GMT

Hi,

I'm trying to configure the I2C for the Kinetis Kl25z dev board (in codewarrior as bareboard project). I want to use the PTE0 and PTE1 pins for the I2C-Communication. The I2C should be configured for 50kHz.

My question, I configured the I2C Modul, like this:

_____________________________________________________________________________________________

#include <stdio.h>

#include "derivative.h" /* include peripheral declarations */

int main(void)

{

int i=0;

//I2C clock on

SIM_SCGC4 |= SIM_SCGC4_I2C1_MASK;

//Port clocks on

SIM_SCGC5 = SIM_SCGC5_PORTA_MASK | SIM_SCGC5_PORTB_MASK | SIM_SCGC5_PORTC_MASK | SIM_SCGC5_PORTD_MASK | SIM_SCGC5_PORTE_MASK;

//Set PIN as I2C1

PORTE_PCR0 = PORT_PCR_MUX(6);

PORTE_PCR1 = PORT_PCR_MUX(6);

//I2C Frequency Divider

I2C1_F = 0x27; //I2C to 50kHz

I2C1_C1 = 0x50; //Enable I2C Modul

I2C1_C1 |= I2C_C1_IICEN_MASK;

for (i = 0; i < 100; i++);

I2C1_C1 = 0x50;

return 0;

}

_____________________________________________________________________________________________

If the I2C is configured right, there should be a clock signal with 50kHz?

What register is missing to activaite the I2C Clock, I have no Clock signal on SCL?

thank you

Re: Kinetis KL25z I2C basic configuration

us1 — Fri, 22 Apr 2016 14:53:54 GMT

Well,

I don't need a corrected code, It would help if someone has a functional i2c implementation - bareboard.

Re: Kinetis KL25z I2C basic configuration

rinipatel — Sat, 23 Apr 2016 04:27:57 GMT

Hi,

You can refer the example I2C bareboard project for kl25z given in Code Warrior. It uses Process Expert component and communicates with on board accelerometer.

-Rini

Re: Kinetis KL25z I2C basic configuration

us1 — Sat, 23 Apr 2016 07:15:05 GMT

Hi,

I wanted to do it without Process Expert, because I need to edit the whole code, so Process Expert is not helpful at all.

Is there no one which has a working i2c example, like it should be done after the ref.book? :smileycry:

Re: Kinetis KL25z I2C basic configuration

mjbcswitzerland — Sat, 23 Apr 2016 19:43:27 GMT

The following is the basic configuration of I2C1 on ports PTE0 and PTE1 on the KL25:

POWER_UP(4, SIM_SCGC4_I2C1); // enable clock to module

_CONFIG_PERIPHERAL(E, 0, (PE_0_I2C1_SDA | PORT_ODE | PORT_PS_UP_ENABLE)); // I2C1_SDA on PE0 (alt. function 6)

_CONFIG_PERIPHERAL(E, 1, (PE_1_I2C1_SCL | PORT_ODE | PORT_PS_UP_ENABLE)); // I2C1_SCL on PE1 (alt. function 6)

I2C1_F= 0x32; // set about 50kHz with 40MHz bus frequency

I2C1_C1 = (I2C_IEN); // enable I2C controller (0x80)

[complete code should check for bus-lockup and recovery before starting too]

See http://www.utasker.com/kinetis/FRDM-KL25Z.html and/or http://www.utasker.com/kinetis/TWR-KL25Z48M.html in case you prefer a complete industrial-quality solution (compatible with all Kinetis parts, including first and second generation parts with double-buffering - working around all erratas).

In your case I think there are three basic problems:

1. You haven't enabled open-drain mode with pull-ups on the ports (although the pull-ups are optional if there are external ones available)

2. The value 0x50 written to I2C1_C1 enables interrupts and master mode but don't actually enable the I2C operation

3. I2C master only generates clocks when actually sending data - if you don't send data the bus remains in high-impedance state so it is normal that there is no clock

Regards

Mark

I2C user's guide: http://www.utasker.com/docs/uTasker/uTaskerIIC.PDF

[1 on 1 support available in English, German and French if ever needed]

Re: Kinetis KL25z I2C basic configuration

kerryzhou — Mon, 25 Apr 2016 02:14:19 GMT

Hi Ulrich,

After you configure the I2C module, you need to transfer the I2C data, then you can see the i2c clock in the sck pin.

Besides, you should better add the external pullup resistor in the sck, sda pin.

Attached it the KL25 i2c driver, you can refer to it.

Any question, please let me know!

Re: Kinetis KL25z I2C basic configuration

us1 — Wed, 04 May 2016 22:40:44 GMT

Hi kerryzhou,

thank you very much. Is there a example for SMBus as well?

thank you

Re: Kinetis KL25z I2C basic configuration

kerryzhou — Thu, 05 May 2016 02:26:35 GMT

Hi Ulrich,

I just have this I2C driver, actually the SMBus is nearly the same as I2C, you can modify the I2C driver to fulfill the SMBUS requirement.

Wish it helps you!

Jingjing