DS90UB949A-Q1: Writing custom EDID content to internal pre programed SRAM

Peter Berenji

Hi,

buy reading post: DS90UB949A-Q1: Internal EDID loaded into device memory - Interface forum - Interface - TI E2E support forums and datasheet of DS90UB949A-Q1, I have understood that pre programed EDID SRAM can be custom changed. So, my goal is that after initial programing, on startup of device, EDID is preloaded from custom pre program SRAM from serializer itself. Does above mentioned post describe this?
Additionally, I do not use TI evo. board (we have our prototype), but I have Python script which can inwrote custom EDID content via I2C pins 14 , 15 (SDA ,SCL) .

Thanks in advance,

Peter

over 2 years ago

0 Jack Scherlag over 2 years ago

TI__Mastermind 38515 points

Hi Peter,

Peter Berenji said:
Does above mentioned post describe this?

Yes, the post you mentioned is for programming the internal SRAM in the 949 after startup. An external I2C controller would program the 949's SRAM block to allow the EDID transfer over to the HDMI source.

Are you having issues with programming the EDID into the 949 SRAM?

Best,

Jack

0 Peter Berenji over 2 years ago in reply to Jack Scherlag

Prodigy 20 points

hello,

so I have difficulties to write to internal SRAM /EDID....
what I am doing is|:

first reg. 0x48 set to 0x0D and

reg. 0x49 and 0x4A to 0x00
after that start writing EDID data:
reg. 0x4B one byte at a time until I put 128 bytes....which were made by Deltacast...

During process I do not have I2C IO errors, checked 0x48 to 0x4A before writing - values are OK... so what I am missing as after restart I again have unchanged EDID (read out buy DeltaCast)

0 Hamzeh Jaradat over 2 years ago in reply to Peter Berenji

TI__Guru** 113140 points

Hello Peter,

Jack is OoO and will be back tomorrow.

+1 Jack Scherlag over 2 years ago in reply to Peter Berenji

TI__Mastermind 38515 points

Hi Peter,

What MODE_SELs are selected on the 949? When using the internal SRAM option for EDID, we want to ensure the HDMI source reads to correct EDID from the SRAM.

Peter Berenji said:
so what I am missing as after restart I again have unchanged EDID (read out buy DeltaCast)

What do you mean after restart you have unchanged EDID? The internal SRAM is volatile and will be cleared during a device reset.

Best,

Jack

0 Peter Berenji over 2 years ago in reply to Jack Scherlag

Prodigy 20 points

On start up I use this

question: subject 128/256 Bytes, they should be written in one I2C write command or for each byte separately with new write command ?

0 Peter Berenji over 2 years ago in reply to Peter Berenji

Prodigy 20 points

and this (missed to add)

0 Peter Berenji over 2 years ago in reply to Peter Berenji

Prodigy 20 points

Hello, actually your question open my mind, so "SRAM is volatile" was the key, somehow I was thinking that it is non Violeta.... Thanks. Now I am able to write my custom EDID with my python script and it is working.... I suppose that EEPROM content can not be accessed as it is efused....

+1 Jack Scherlag over 2 years ago in reply to Peter Berenji

TI__Mastermind 38515 points

Hi Peter,

Glad to hear that the custom EDID is working. There is an internal eFuse that will load into the internal SRAM but this can't be modified. We recommend using a script or on-board EEPROM to program EDID on startup.

Let me know if you run into any further issues.

Best,

Jack

0 Peter Berenji over 2 years ago in reply to Jack Scherlag

Prodigy 20 points

since now EDID and script is valid, I need to manage correct sequence for starting the HDMI receiver. So I need first to load the EDID SRAM with script and just than I activate the HDMI receiver. So to me it looks like that MOD_Sel_1 / CTL_EN should be brought to HI during power up (voltage reading) and after script is loaded CTL_EN in register 0x54:bit8 is set to 0 so HDMI is enabled and only than hot plug detection will work or I am mistaken?

0 Jack Scherlag over 2 years ago in reply to Peter Berenji

TI__Mastermind 38515 points

Hi Peter,

This sequence is correct. Enabling external controller override will allow you to program the EDID before the HDMI receiver is initialized. Once HDMI control is passed to the 949, the HDMI initialization will finish.

Best,

Jack