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ADV7441A - status registers

Question asked by msauer on Feb 3, 2011
Latest reply on Mar 21, 2011 by raymondcarter



we use the ADV7441A as analog frontend to view analog RGB signals on a lcd. If I don't connect a signal the ADV7441A produces a random VSYNC signal and no HSYNC signal on his outputs. Our software detect a signal lost and mode change through measurement of the sync signals. This don't work if the ADV7441A will alwas produce a VSYNC, so I deactivate the free run mode.

I try to use the status register to detect a sync lost, but SSPD_VALID bit is always set and STDI_VALID is alwys cleared independet if I connect a signal or not.

In software manual ADV7441A Rev D, June 10, are the bits VS_ACT and HS_ACT in Reg 0xb5, User Map, inverted. If I connect a signal the bit is set and if I disconnect the signal the bit is cleared.


This is my initialitation:


User Map; 0x03; 0x10
User Map; 0x05; 0x02
User Map; 0x06; 0x07
User Map; 0x1d; 0x40
User Map; 0x3c; 0xa8
User Map; 0x37; 0x01
User Map; 0x47; 0x0a
User Map; 0x68; 0xf2
User Map; 0x7b; 0x1d
User Map; 0xf4; 0x15
User Map; 0x87; 0xa8
User Map; 0x88; 0x00
User Map; 0x8f; 0x00
User Map; 0x90; 0x00
User Map; 0xab; 0x00
User Map; 0xac; 0x00
User Map; 0x91; 0x10
User Map; 0xc4; 0x40


Do you have a solution how I can detect a signal lost?


Thank you for your help


best regards


martin sauer