custom speed in I2C

Using Arduino Networking, Protocols, and Devices
#1

Hi all, I wounder how to setup custom freq for I2C bus?
I need to get Freq 346 Khz on clock bus. I tried to setup TWBR bit using formuala and the table:

freq = clock / (16 + (2 * TWBR * prescaler))

TWBR prescaler Frequency

12 1 400 kHz (the maximum supported frequency)
32 1 200 kHz
72 1 100 kHz (the default)
152 1 50 kHz
78 4 25 kHz
158 4 12.5 kHz

Wire.begin ();
TWBR = 15;

However send only one data pakeg with 124Khz freq and then just hangup and.
I am following with this project: Gammon Forum : Electronics : Microprocessors : I2C - Two-Wire Peripheral Interface - for Arduino
It all works up to 100Khz unfortunately.

#2

Just a matter of curiosity -- why do like to operate the I2C Bus at 346 kHz speed?

#3

Ok looks like I found issue. I have added 4.7K pull up resistors and now I am able to adjust frequency by setting up TWBR bit. Thanks a lot!

GolamMostafa:
Just a matter of curiosity – why do like to operate the I2C Bus at 346 kHz speed?

I am trying to connect to custom build industrial dishwasher machine

#4

7nebo7:
Ok looks like I found issue. I have added 4.7K pull up resistors and now I am able to adjust frequency by setting up TWBR bit. Thanks a lot!

I am trying to connect to custom build industrial dishwasher machine

Why is 54 kbit/sec difference in speed an important issue for your dishwasher machine?

#5