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Richard-TX
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Location: North Texas

B+ disable ID_EEPROM

Sun Oct 19, 2014 4:29 pm

I have an existing application that uses both I2C buses on a model B. Since the B+ has redefined the other I2C bus, this is an issue. I understand the whole HAT idea, but this hardware application could not possibly be a HAT.

Since my application has no provision for an EEPROM nor would it benefit from it, is there some way that I can reconfigure the firmare/kernel so that the ID_EEPROM I2C bus is converted to a general purpose I2C bus?

If I have to, I am willing to rebuild the Linux kernel/firmware so that I regain the use of the 2nd I2C bus. I just need some help or guidance in this regard.

Thanks
Richard
Doing Unix since 1985.
The 9-25-2013 image of Wheezy can be found at:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2013-09-27/2013-09-25-wheezy-raspbian.zip

ShiftPlusOne
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Re: B+ disable ID_EEPROM

Sun Oct 19, 2014 4:58 pm

I think it was decided that there will be a 'classic mode' config option, but you should be able to just add bcm2708.vc_i2c_override=1 to cmdline.txt and use it like you normally would. The firmware will check for an attached eeprom first, but that shouldn't affect your device.

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Richard-TX
Posts: 1549
Joined: Tue May 28, 2013 3:24 pm
Location: North Texas

Re: B+ disable ID_EEPROM

Sun Oct 19, 2014 5:41 pm

Well, that certainly helps. Is there any documentation or source tree that I can look at regarding the scan at boot for the eeprom?

Depending on what the reading of the EEPROM does, It may be possible that the addition of an EEPROM could help.
Richard
Doing Unix since 1985.
The 9-25-2013 image of Wheezy can be found at:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2013-09-27/2013-09-25-wheezy-raspbian.zip

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5708
Joined: Fri Jul 29, 2011 5:36 pm
Location: The unfashionable end of the western spiral arm of the Galaxy

Re: B+ disable ID_EEPROM

Sun Oct 19, 2014 5:44 pm

I don't think that's a thing that happens yet.

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Richard-TX
Posts: 1549
Joined: Tue May 28, 2013 3:24 pm
Location: North Texas

Re: B+ disable ID_EEPROM

Sun Oct 19, 2014 7:51 pm

hmmm. I guess I will have to wait and see what, if anything, will happen in the future. Thanks for the info.

richard
Richard
Doing Unix since 1985.
The 9-25-2013 image of Wheezy can be found at:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2013-09-27/2013-09-25-wheezy-raspbian.zip

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