Whoever said - reading the datasheet goes a long way, was not lying. :)
So I read it, twice, and found it quite enlightening. To summarise: I found
out how to set the Battery Regulation voltage and charge current, thanks to
register descriptions on page number 33-35, which use the formula
VBATREG = 3.5 V + VBREGCODE × 20 mV
and ICHARGE = 500 mA + ICHRGCODE × 100
mA
Also, I found the address of the EVM for referring in my BBB I2C code as : 0x6B
(1101011 in binary) .
Now, I am left with two, seemingly non-trivial questions,
1. * How to do I write to the registers* like the Status/Control Register
with a memory location of 00, Control/Battery Voltage Register with a
memory location of 02, etc. I learnt direct register manipulation (DRM) but
then experts suggested that using API function calls is a safer method to
use than DRM (I dont think such API functions are available for BQ-24261,
there was a mention of a public library here
https://lkml.org/lkml/headers/2015/9/6/91 but I couldnt locate the actual
header file) , so I am not as thorough with the process. A two line snippet
would really help in clarifying the concepts.
2. *Choice of functional mode*:Section 9.4 of datasheet, lists details
about 19 possible functional modes for operating the EVM. Which of these is
the suggested one ? I understand that this might be application specific,
but any pointers on this selection, or this is done implicitly by setting
the appropriate registers through the above step.
- Thanks
Chintan Pathak
On Tuesday, September 22, 2015 at 8:55:43 PM UTC+5:30, Ron B. wrote:
>
> 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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