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AD9389B: EDID reread register (0xC9[4])

Question asked by mra on Mar 12, 2012
Latest reply on Mar 12, 2012 by mattp

"AD9889B/AD9389B programming guide, Rev. A, October 2010" chapter 4.5.1.4 says:

 

EDID Reread Register (0xC9[4])

If the EDID data is read in and the host determines that the data needs to be reread, this bit can be set from 0 to 1 for

10 times consecutively, and the current segment will be reread each time. This register should be toggled from 0 to 1

for 10 times consecutively to ensure a successful capture of the register value. This could be useful if the EDID

checksum is calculated and determined not to match.

 

Another method to reread the EDID is to toggle the Main Power Down register bit (0x41[6]) from 0 to 1.

 

I have connected the transmitter to a Quantum Data 980 video analyzer and tried to toggle bit 0xC9[4], but the chip doesn't read the EDID from the analyzer. What am I doing wrong?

 

If I toggle the Main Power Down register bit (0x41[6]) (from 0 to 1 AND BACK TO 0), AD9389B rereads the EDID.

 

Regards,

     Mats Randgaard

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