Re: [avr-gcc-list] TWI pullup resisor values

[Douglas Dotson]

OK, Thanks! When the 3.3K pullups are in place,
performance grinds to a slow crawl. Even when the
slave device is removed. Feels like a swarm of
interrrupts are keeping things very busy. If I 
disable the interrupts, things run fine.

Doug

--- Andreas Krause <address@hidden> wrote:
> Douglas Dotson wrote:
> > I am trying to communicate with an I2C
> > device (DS1340 RTC). When I try to send
> > info to the RTC, system performance slows
> > down to a crawl. It appears that it is being
> > swamped with interrupts. Also, unable to read
> > anything from the RTC. Is it possible that
> > improper pullups on SDA and SCL are causing this?
> > I'm using 3.3K pullups. Would it be better to 
> > just use the internal pullups already part
> > of the port circuitry? Bit rate is 100K.
> > 
> > THanks!
> > Doug
> 
> standard values are 4.7k on SDA and SCL according to
> the philips 
> databook. But 3k3 resistors should work as well.
> 
> regards,
> Andreas
> 


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