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i2c issue

Submitted by ffiquet on Thu, 05/06/2010 - 10:05

Hi,
I have an issue concerning i2c bus.
When I load i2c-core.ko (insmod), I get the following messages:
[specs: stamp9g20evb]
-------
i2c_core: Unknown symbol i2c_board_list
i2c_core: Unknown symbol i2c_first_dynamic_bus_num
i2c_core: Unknown symbol i2c_board_lock
-------
Do I miss something ?
How can I fix it ?

Regards

Fred

‹ PortuxG20 interfacing questions: /dev/ttyUSB and 1-wire Stamp9G20 rescue flashing procedure ›
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Re: i2c issue

Submitted by aehrlich on Thu, 05/06/2010 - 11:23.

You most probably missed to load/compile the GPIO-based bitbanging I2C under I2C Hardware Bus support in menuconfig. Also switch on the I2C device interface if you want something like /dev/i2c-0 or similar to work on.

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Re: i2c issue

Submitted by ffiquet on Thu, 05/06/2010 - 16:31.

Achim,
I am still in trouble with i2c support,
In menuconfig, I have selected:
I2C Support
--> I2C Device interface
-->I2C Algorithms
----->-M- I2C bit-banging interface
-->I2C Hardware bus support
-----> GPIO-based bitbanging I2C

I built modules only and installed them in /develop/modules/
I have copied "/driver/i2c" directory in target board

When I install i2c-core, I still get messages !
Can you detailed me the procedure?

Fred

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Re: i2c issue

Submitted by aehrlich on Mon, 05/10/2010 - 11:32.

The problem is the kernel. Once I2C is activated, there is init code in the stamp9g20 boardfile, which is needed to activate I2C. So you have to flash the new kernel (like described in the Linux-Guide) as well before inserting the modules.

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Re: i2c issue

Submitted by ffiquet on Wed, 05/12/2010 - 09:30.

I have generated a new kernel including i2c driver.
Now I have an i2c entry in /dev/. Thank you.
I have questions concerning pins assignment:
- i2c is using pins 55 and 56 (dmesg), I guess it is on IO interface. How can I change those pins (I would prefer to use pins 47, 48 wich are originally dedicated to i2c link.
- Driver is based on bitbanging, does it mean that I can deactivate TWI management in PMC registers ?

Fred

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Re: i2c issue

Submitted by cglindkamp on Wed, 05/12/2010 - 10:20.

- i2c is using pins 55 and 56 (dmesg), I guess it is on IO interface. How can I change those pins (I would prefer to use pins 47, 48 wich are originally dedicated to i2c link.
These are actually the same pins. Pins 55 and 56 from the Kernel log map to PA23 and PA24 (PIOA base is 32, so 32+23=55 and 32+24=56), which are pin 47 and 48 on the Stamp9G20 IO interface.

- Driver is based on bitbanging, does it mean that I can deactivate TWI management in PMC registers ?
You do not have to do that. Without the TWI hardware driver, the peripheral is never activated in the PMC.

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