ATTiny45 with I2C on DAC6571

nobner · Joined: 29 Apr 2015 Posts: 11

Hello together,
i'm trying to do with I2C and a ATTiny45 a voltage output on an DAC6571. This works only, if i use I2Cdelay.
Now i use I2Cdelay=10.
In the Bascom Helpfile is written, 10 is a Busfrequency at 100KHz "but it depends on the used crystal". I'm using the internal 8MHz oszillator.
If the 100KHz are defined for a 4MHz oszillator, is it then so, that I2Cdelay=10 with a 8MHz oszillator is automatically a Busfreuency of 200KHz?
I didn't found a direct context between oscillator frequency and I2Cdelay-value?
Thanks for a hint,
kind regards
Norbert

(BASCOM-AVR version : 2.0.7.8 )

albertsm · Joined: 09 Apr 2004 Posts: 5016 Location: Holland

you can best use the USI. See samples\USI\
of course soft mode works too.
Delay is using waitus internally. So only the parameter value will make a difference.
Code in lib : @genus(___I2CDELAY)

In earlier versions there was a simple delay loop. Later the clock independent waitus was used.
But when having TWI or USI you can better use that.