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ADV7842 EDID read problem

Question asked by poptoxin on May 7, 2015
Latest reply on May 15, 2015 by poptoxin


     There is a issue when I use  ADV7842. The problem is that HDMI DDC can not read right data from my chip. I have wrote EDID data into my chip and when I connect HDMI and the chip, it could not work. So I mesured the signals with an oscilloscope. Turned out that ddc have read wrong data.

     From oscilloscope we can see the data that ddc read was '0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF', when the right data is '0x00 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0x00'. I do not know what cause this. I have read some similar discussions, someone said that SPA_PORT_A was causing this problem. So I read it's value, on my chip, repeater[0x72-0x73]=0x1fff and 0x76=0xff by default, which is not what the soft spec.specify.

     Another confusing thing is that ddc write 0x30 to adv7842, I know that '0x50' represents I2C address 0xA0.

     So what should I do to make it correct? I use Playstation3 as HDMI source.