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Does ADV7612 Require Repeated Start When Reading

Question asked by jasonuy on Apr 7, 2017
Latest reply on Apr 10, 2017 by GuenterL

I have an EVAL ADV7612-7511 board and probing the I2C bus, I can see the BF542 does a repeated start when reading the registers of ADV7612.  I checked the datasheet for 7612 and I did not see any requirement about this.  I connected my board to the EVAL kit using the I2C (so there's two I2C master on the bus now).  I made sure the BF542 is quiet so it doesn't interfere with my CPU.  My CPU/i2c-tool doesn't seem to use repeated start.  It always insert a stop after every command.  For example, when I do a write, this is what my CPU does.

 

S SlaveAddr[W] RegAddr P S SlaveAddr[R] RegAddr READ P

Unfortunately I don't get an ACK after SlaveAddr[R].  The BF542 does this.

 

S SlaveAddr[W] RegAddr S SlaveAddr[R] RegAddr READ P

 

The only difference is mine has a stop bit whereas the BF542 doesn't which leads me to my question.  Any clarification would be useful.  

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