Using I2C on a i.mx28 EVK

[Lukas1z]

Hi, I am a beginner when it commes to these boards. I want to connect a TPM to the board via I2C and could not figure out witch pins I have to connect. I know I could use the RS32 with muxing, but that would take away my debug option. Would be great if someone could help me with this.

[ArtyomKamshilin]

Lukas,

Do you have a scope? Put it on to J88 SCL pin and try a transaction - you should see square wave about 92 KHz. If it's there, there's likely something wrong with your device. If not, I2C bus is not getting initialized properly. Are you using /dev/i2c-0 to access I2C? It's available in LTIB kernel configuration.

If you see the SCL pulses but still no luck, I recommend spending a couple hundred dollars on a I2C bus analyzer. It will read what's flying on SCL and SDA. Here are two options:

http://www.zeroplus.com.tw/logic-analyzer_en/products.php?pdn=1&product_id=250

(inexpensive, works)

http://www.totalphase.com/products/beagle_ism/

(a bit more expensive, better software)

[NicolasIzquierd]

Hi Lukas...

About the LTIB package Im not familiar with that, maybe somebody of software can help you to bring up that i2c.

-ni

[Lukas1z]

Hi, I activated all the I2C devices in the LTIB confguration but still can't find my I2C device on the J88. Is there anything else I need to do?

[NicolasIzquierd]

Hi 

You do not need to add the eeprom (24LCxx-I/P) if you are going to use it, you can add or make you connection from here (J88) to your chip,

something that I forget, do not add pull up resistor because the board already have them for SCL & SDA.

-ni

[Lukas1z]

Hi, Can i use the J88 by just connecting my chip with the pins or do i have to use a 24LCxx-I/P as stated in imx28_evk_revD_sch.pdf [1]? [1] http://code.google.com/p/trytoucan/downloads/detail?name=imx28_evk_revD_sch.pdf

[NicolasIzquierd]

Hi Lucas.

Maybe SAMTEC directly can help you with a sample but if not, the no populated dip socket  with reference J88 pins 6 I2C0_SCL & pin 5 I2C0_SDA you can make the connections.

regards

-ni

[Lukas1z]

Hi,

is there a cheaper way to use this pins than buying one of these [1].

[1] http://at.farnell.com/samtec/hqcd-060-18-00-seu-sed-1/micro-high-speed-cable-interfaces/dp/1822490

[Lukas1z]

Hi Nicolas, Thank you for your answer it helped a lot!

[NicolasIzquierd]

Hi Lukas,

If you need the I2C to connect externally to other board in the J78 (LCD PORT) of the EVK, pins 31 for SCL and pin 29 for SDA if this is in use you can move to the J63 pin 109 & 107, respectively. Those net are connected to the default state of the pad, this means after reset you will have i2c communication by default.

hope this can help you.

-ni