Your source for all things bq24261 will be the datasheet 
<http://www.ti.com/lit/ds/symlink/bq24260.pdf>.  It describes the 
registers, how to use them, and gives you the I2C address at the bottom of 
page 27.  The bq24261 will work fine with a 3.3V I2C interface.  It will 
get it's own internal power from the DC source used for battery charging 
(on eval board J1).  Eval board documentation is here 
<http://www.ti.com/lit/pdf/sluuab0>.

My drawing would probably look more like:
BBB SCL  <-->  SCL (J15)
BBB SDA  <-->  SDA  (J15)
BBB GND  <-->  GND  (J15)

Add pull-ups between SCL <-> BBB 3V3, and SDA <-> BBB 3V3.  I'd probably 
use 10k.  Then, it's all software.

-Ron




On Tuesday, September 22, 2015 at 8:52:41 AM UTC-5, Chintan Pathak wrote:
>
> Hey Ron, 
>
> You have been super-helpful, and I believe together we have nearly cracked 
> it. 
>
> I am beginning to get a feel for I2C and I have come up with a schematic 
> for connection, which I present below for review and comments. 
>
>
> <https://lh3.googleusercontent.com/-DLOTnkK_ihU/VgFbQtMxLZI/AAAAAAAABMk/FvQO-ctXTbw/s1600/i2c_interface_schematic.png>
>
>
> I plan to use pull-ups of 47k each and a supply of 3.3V from BBB. 
>
>
> I have also requested help from TI-E2E, but I wanted to know, if this 
> voltage is sufficient / proper for our charger ? 
>
>
> Also, how can I get the address of our EVM (charger) for use in the code 
> as in your # define statement in this example 
> http://andicelabs.com/2013/06/linux-using-i2c-from-user-land/  ? 
>
>
> Will let you know how this goes. 
>
>
> - Thanks
>
> Chintan Pathak 
>
>
> On Tuesday, September 22, 2015 at 5:29:45 AM UTC+5:30, Ron B. wrote:
>>
>> Your original question seemed to be more about I2C code examples. 
>>  Anyway, I don't see any reason why you can't do what you're asking.  The 
>> eval board's I2C interface is brought out to a header and you'd just hook 
>> that up to the bone's I2C bus (be sure to also connect the boards' grounds 
>> together).  The eval board doesn't make any assumptions about power so 
>> there are no I2C pull-ups on it.  If you need to add pull-ups to the I2C 
>> lines, be sure to use 3v3 from the bone's header.
>>
>> While not 100% relevant, I have two I2C posts here 
>> <http://andicelabs.com/2013/06/linux-using-i2c-from-user-land/> and here 
>> <http://andicelabs.com/2013/07/adafruit7segment/> with simpler examples.
>>
>> -Ron
>>
>> On Monday, September 21, 2015 at 12:13:27 PM UTC-5, Chintan Pathak wrote:
>>>
>>> Hey Ron, 
>>>
>>> Your work at andicelabs.com seems fantastic. Long live Open source :)
>>>
>>> Just to be clear about my question, I want to power a battery using the 
>>> TI battery charger board, BQ24261 and I want to control (program) the 
>>> charger  board using a Beaglebone black. Reading the datasheet of the 
>>> charging board, I found that, it can be controlled via a GUI, that can be 
>>> accessed by interfacing the charging board to a PC using a USB-GPIO 
>>> interface board. 
>>>
>>> In absence of the said board, and with the need to programmatically set 
>>> the charging voltage for my battery, I plan to use the BBB. 
>>>
>>> Your code in powercape.c is quite exhaustive, I wanted to further know, 
>>> whether I will need any additional hardware to connect the charging board 
>>> to BBB, and any other information / source relevant to this topic. 
>>>
>>> - Thanks 
>>> Chintan Pathak 
>>>
>>>
>>>
>>>
>>> On Monday, September 21, 2015 at 8:26:08 PM UTC+5:30, Ron B. wrote:
>>>>
>>>> Hi Chintan,
>>>>
>>>> I don't use I2C to control the charger, but I do use it to talk to the 
>>>> power monitor and the supervisor.  Our code for the host-side I2C 
>>>> utilities 
>>>> are on Github 
>>>> <https://github.com/AndiceLabs/PowerCape/tree/master/utils> and should 
>>>> make a reasonable example.
>>>>
>>>> -Ron
>>>>
>>>> On Monday, September 21, 2015 at 2:58:12 AM UTC-5, Chintan Pathak wrote:
>>>>>
>>>>> I have a battery charger : 
>>>>> http://www.ti.com/tool/BQ24261EVM-079?keyMatch=bq24261evm-079&tisearch=Search-EN-Everything
>>>>>
>>>>> and I want to program it using the BBB I2C. Can I get any code sample 
>>>>> to proceed or any guidance ?
>>>>>
>>>>>
>>>>>

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