FPGA DVI output with CH7301

Hi

does anybody have some experience with DVI output using Chrontel  DVI 
transmitter (CH7301)

the DVI transmitter works in analog RGB bypass mode OK, I see a pong game on 
analog monitor

but in DVI mode there is nothing on the output, even DVI Clock is missing, 
DVI hotplug detect works, eg the DVI transmitter shuts down when I unplug 
the connector except that I can see nothing that tells me anything why the 
DVI transmitter is not sending anything. All voltage levels seems to 
correct, the bias voltages are ok, XCLK is 25MHz H/V Sync DE I think are 
also valid.

Chrontel datasheet doesnt tell much, I have set the DVI power control bits 
to active, and there doesnt seem to be any secret sequence to enable the DVI 
output

Antti

PS if someone is able to provide consulting help that helps me to get the 
CH7301 working I may be able arrange a free eval board with CH7301+V4 as 
thank you gift. At least I will do my best to arrange it.

>"Antti Lukats" <antti@openchip.org> schrieb im Newsbeitrag 
>news:dpavmu$cb$01$1@news.t-online.com...
> Hi
>
> does anybody have some experience with DVI output using Chrontel  DVI 
> transmitter (CH7301)
>
> the DVI transmitter works in analog RGB bypass mode OK, I see a pong game 
> on analog monitor
>
> but in DVI mode there is nothing on the output, even DVI Clock is missing, 
> DVI hotplug detect works, eg the DVI transmitter shuts down when I unplug 
> the connector except that I can see nothing that tells me anything why the 
> DVI transmitter is not sending anything. All voltage levels seems to 
> correct, the bias voltages are ok, XCLK is 25MHz H/V Sync DE I think are 
> also valid.
>
> Chrontel datasheet doesnt tell much, I have set the DVI power control bits 
> to active, and there doesnt seem to be any secret sequence to enable the 
> DVI output
>
> Antti
>
> PS if someone is able to provide consulting help that helps me to get the 
> CH7301 working I may be able arrange a free eval board with CH7301+V4 as 
> thank you gift. At least I will do my best to arrange it.
>
>
comments to myself - need to learn to use DSO the DVI output signals are 
there just
with a small swing about 180mV peak to peak

when the clock mode is set to DDR the I see DVI clock twice the XCLK, when 
single
clock edge mode then the XCLK is seen as DVI clock what sounds proper, also 
the
DVI data lines have something on them what looks like it should like (when 
using
500MHz bandwith DSO)

DVI monitor still fails to detect signal, so something is still too badly 
wrong, but
at least I know there is some signal going out so it makes sense to proceed.

anway if there is some trick or advice that helps to get valid DVI out I am 
all ears

Antti

Hi Antti,

where are the input signals of the Chrontel coming from ?

The active clock edge should be around 1 to 1.5 ns later than the
other signals edges.

I am using the Chrontel for DVI digital and analog output and it works.
The image source is a Silicon Image which sends data to an FPGA.
In the FPGA the data are converted to DDR signals. Also the clock
adjustment is managed in the FPGA.

Rgds
Andr=E9

<ALuPin@web.de> schrieb im Newsbeitrag 
news:1136213073.260732.49510@g49g2000cwa.googlegroups.com...
>Hi Antti,
>
>where are the input signals of the Chrontel coming from ?
>
>The active clock edge should be around 1 to 1.5 ns later than the
>other signals edges.
>
>I am using the Chrontel for DVI digital and analog output and it works.
>The image source is a Silicon Image which sends data to an FPGA.
>In the FPGA the data are converted to DDR signals. Also the clock
>adjustment is managed in the FPGA.
>
>Rgds
>Andr&#4294967295;

Hi Andre

thanks for fastreply - well I am only about to test an PCB board that 
'functional test' so I implemented some video sync generator and then tested 
it with CH7301 in analog bypass mode, everything fine. I played a little bit 
with the clock edges, etc.

the problem is that as soon as try to see the same signal on DVI monitor it 
either remains blank or says no signal detected. As much as I understand in 
order to enable DVI output 0xC0 write to register 0x49 is sufficent 
(assuming everything else is ok for the analog mode).

But what I see exactly nothing. I assume my signal polarities are ok

DE active high
H/V sync active low

my my signal source in FPGA is way off and the monitor doesnt recognize it, 
but still weird. At the moment I am not even sure if the DVI clock is 
accepted by the DVI receiver (eg TFT display).

a TFT display is not really a good thing to test bring up of an DVI 
transmitter :(

I created a DVI RX active termination emulation board and measured the 
signals using it, the signal swing is same as if monitor is attached - well 
it is way below the standard requirements, but maybe my DSO doesnt measure 
the signal correctly :(

at the monent I would be very happy to have

1) known good DE+h/v sync generator IP that generates valid signals for DVI 
output to be accepted by the monitor

or I can try to check my signal timings and adjust them and hope that one 
day the monitor will accept the signals


Antti

What frequency / resolution are you working with ?

Rgds
Andr=E9

<ALuPin@web.de> schrieb im Newsbeitrag 
news:1136217553.293210.133940@g43g2000cwa.googlegroups.com...

What frequency / resolution are you working with ?

Rgds
Andr&#4294967295;

basic VGA, 25MHz XCLK

after some more testing

1) if I turn monitor off then on again, it remains ON (no auto power off) 
and does not display loss of signal
2) when I then write 0x00 to 0x49 shutting down the DVI output then monitor 
does respond with 'loss of signal'

so I assume my sync/de signals are messed up - will be fighting again 
tomorrow

Antti

Did you set the "Clock Mode Register" corresponding to your
single-edge/dual edge clocking ? And the "DVI PLL Filter Register"
corresponding to your frequency ?

Rgds
Andr=E9

<ALuPin@web.de> schrieb im Newsbeitrag 
news:1136294247.789067.18020@g14g2000cwa.googlegroups.com...
>Did you set the "Clock Mode Register" corresponding to your
>single-edge/dual edge clocking ? And the "DVI PLL Filter Register"
>corresponding to your frequency ?
>
>Rgds
>Andr&#4294967295;

the clock mode is set properly, but I did not touch the DVI PLL Filter 
Register leaving at factory default

thanks for suggestions

Antti
PS your email is non-responsive, please email me in private

<ALuPin@web.de> schrieb im Newsbeitrag 
news:1136294247.789067.18020@g14g2000cwa.googlegroups.com...
>Did you set the "Clock Mode Register" corresponding to your
>single-edge/dual edge clocking ? And the "DVI PLL Filter Register"
>corresponding to your frequency ?
>
>Rgds
>Andr&#4294967295;

Hi Andre,

that was it! I should really to the RTFM thing more often, I had looked at 
those regs
but they had 'use default' value for them so I assumed they have some good 
default
at powerup but they dont - thats actually written in the datasheet as well

so after writing the proper defaults the DVI TFT monitor did come alive, no 
issues!

Thank you!

Antti

Read the EDID information off the monitor.  You'll need a PC with a DVI port 
and the utility found here:
http://www.viewsonic.com/support/drivers/driver_information.cfm?product=all&formName=product&key=87

Make sure the FPGA is generating timings supported by the monitor you are 
using.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian
eCinema Systems, Inc.

To send private email:
x@y
where
x = "martineu"
y = "pacbell.net"


"Antti Lukats" <antti@openchip.org> wrote in message 
news:dpbj0l$6ea$00$1@news.t-online.com...
> <ALuPin@web.de> schrieb im Newsbeitrag 
> news:1136217553.293210.133940@g43g2000cwa.googlegroups.com...
>
> What frequency / resolution are you working with ?
>
> Rgds
> Andr&#4294967295;
>
> basic VGA, 25MHz XCLK
>
> after some more testing
>
> 1) if I turn monitor off then on again, it remains ON (no auto power off) 
> and does not display loss of signal
> 2) when I then write 0x00 to 0x49 shutting down the DVI output then 
> monitor does respond with 'loss of signal'
>
> so I assume my sync/de signals are messed up - will be fighting again 
> tomorrow
>
> Antti
>
>
>