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ADV7842: “STORE_EDID” and SPI-interface to E-EDID EEPROM

Question asked by Sasa on Jul 9, 2014
Latest reply on Aug 8, 2014 by Sasa

Hi All

 

1. Command “STORE_EDID”, Repeater.0x7E[0] (Self-Clearing) (UG-214.pdf#page180) - this command hangs! Why?

 

After setting this bit in “1”, ADV7842 to SPI-interface send “Write Enable (0x6)”, then up-and-down signal EP_CS# on 30ns (must be more 50..150ns), then send “Write 0x00 to addr 0x100 (0xA0, 0x00, 0x00)” and then nothing do: EP_CS#= EP_SCK= EP_MOSI=0. Bit “STORE_EDID” remains in 1. Reset of ADV7842 no change his state and state of signals of SPI-interface – only power off-on reset this hang-up. In attachment - screenshot (1-CS#, 2-SCK, 3-MOSI, 4-MISO, 2us/div).

 

 

2. Pulse on EP_CS# between commands is 30ns – it is very shortly! It must be >50ns for EEPROM from Microchip and more (up to 140ns) for other. It is bug?

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