nRF51422 communicating with SAA1064 via TWI/I2C

[Michel]

The last few weeks I'm working with the nRF51422 and run in to several TWI/I2C issues. All of them I could solve except an issue with a SAA1064 7segment display driver from NXP.

Depending the device selection the I2C address of the SAA1064 should be 0x70, 0x72,0x74 or 0x76. When communicating non of these address will return an ACK. I'm using sd_twi_hw_master.c.

I do have TWI/I2C running because I can communicate with the MPU-9150 and an other sensor. But it fails on the SAA1064.

Is there maybe a small difference/issue with TWI and I2C?

Does anybody know where to look to solve this issue?

[Michel]

I noticed the missing TWI stop bit. That's no problem indeed.

I'm using the development boards (PCA10006 and 7). With a battery powered supply of 3.2 to 3.3V. The supply to the SAA is 5V.

Looking at the datasheet of the SAA the SDA and SCL should be at least 3.0V which should not be an issue because the supply of the nRF is 3.2V.

While writing this reply I don't know what I changed, but it's working now. I will take a closer look at the changes the last few hours.

For now thanks for helping.