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ADV7611 I2C Addresses. 2 devices per design

Question asked by Spink Employee on May 6, 2016
Latest reply on May 6, 2016 by GuenterL

Hi,

 

A design is using 2 ADV7611 devices per board - and running into integration issues.

 

Device #1 has ALSB floating  (can be either floating or pulled down according to datasheet)

Device #2 has ALSB pulled up. 

 

After reset, both parts will have 0x98.  When reading back the device with address (0x98), we get a response (good). 

We are unable to determine which - of the two devices -  the response is coming from though. 

 

After I2C write (high) to IO 0x1B, SAMPLE_ALSB, device,
device #1 should be 0x98 (floating).  device #2 should be set to 0x9A
(PU).

 

However after reset, we are able to read from device #2 (0x9A) but can no longer talk to device #1 (0x98).

 

Note:  The reset line is connect to BOTH device.

 

Has this issue been observed before?  Please recommend a fix.  When you WRITE (high) to IO 0x1B to device 0x98 (and both devices are 0x98), shouldn’t it mess up the I2C Bus?  Are we supposed to keep one of the two devices in reset during the configuration of the first device?

 

REFERENCE: PG 173 of UG-180

 

Thx.

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