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

[Douglas Pearless]

Hi Harald,

Thanks for the assistance.

It turned out that the TwMasterTransact routine, when you pass the 
address of an array for the transmit buffer, it starts the 'read' from 
the data[1] not data[0], so it was skipping the register address of the 
DS1337 which was in the zeroth position (data[0])

When I figured that out, and corected my code, it then worked perfectly!

Rather bizzare, but then I am no C expert!

Cheers DOuglas

Douglas Pearless wrote:

> There are only two 2k2 pull ups on SDA and SCK to +5v and the DS1337.  
> There are no other wires or connections!
>
> Cheers Douglas
>
> Harald Kipp wrote:
>
>> Hi Douglas,
>>
>> At 16:30 16.03.2005 +1300, you wrote:
>>
>>>    rc = writeRTC(sla,0x0E,dataRTC,2); //on the i2c bus I get 
>>> "<start> 110100000 <SDA goes high>  000000000  000000000 
>>> 000000000<stop>
>>> //where did the 0x0E go which should have been immediately after 
>>> <SDA goes high>
>>> //I checked the wrteRTC routine and it does pass 0x0E 0x00 0x00 in 
>>> the 'data field to TwMasterTransact
>>
>>
>>
>> What about hardware? You are aware, that I2C is open
>> drain? Did you add pull-ups? Anything else connected,
>> which may drive the bus low?
>>
>> Harald
>>
>> _______________________________________________
>> En-Nut-Discussion mailing list
>> En-Nut-Discussion at egnite.de
>> http://www.egnite.de/mailman/listinfo.cgi/en-nut-discussion
>>
> _______________________________________________
> En-Nut-Discussion mailing list
> En-Nut-Discussion at egnite.de
> http://www.egnite.de/mailman/listinfo.cgi/en-nut-discussion
>