[En-Nut-Discussion] TWI aka I2C, not getting an ACK back?

Douglas Pearless Douglas.Pearless at pearless.co.nz
Wed Mar 16 02:51:22 CET 2005


Hi All,

I have solved my problem.

The lack of an ACK was for reasons unknown, I turned the unit off for a 
day and it started to work when I turned it back on, rather suspicious!

Also one of my probes (a DSO watching the square wave output from the 
DS1337/DS1307 to verify I have turned on that output) was not properly 
grounded (a loose wire in the oscilloscope probe) and that intermittent 
worked.

Cheers Douglas

> Hi Harald,
>
> Yes I know about the 1 bit.
>
> I have traced further and found that I hadn't setup the speed 
> correctly (it was too fast, well over 400k!)
>
> Cheers Douglas
>
> Harald Kipp wrote:
>
>> Sure, that you used the 7-bit address?
>>
>> The Nut/OS twi driver will shift this left by one bit
>> to include the R/W bit.
>>
>> Harald
>>
>> At 22:44 13.03.2005 +1300, you wrote:
>>
>>> Hi,
>>>
>>> I am trying to interface a DS1307 to the TWI.
>>>
>>> I send it the address, and do not get an acknowledge back (I used a 
>>> logic analyser to verify the return code I was getting in the 
>>> software).
>>>
>>> Any ideas (yes tried a DS1337 which has the same address too).
>>>
>>> Cheers Douglas
>>
>>
>>
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