HDMI output for A1200?

[Stedy]

Carl,

Why not use a DVI device like the SiI1162?

Datasheets are available without an NDA for HDMI parts and you also open up the possibility of DVI monitors.

HDMI TVs can take a DVI input take a look here at the HDMI website.

To clock the DVI chip from Lisa use the Sync On Green (SOG) output, this will be a composite (hsync and vsync) combined signal. The SII1162 requires separate HSYNC/VSYNC signals. You can either use a sync stripper like the LMH1980 or if you use programmable logic, use that.

Of course, it would be worth double checking that the SOG output is a standard Video sync output first otherwise it may need conditioning/converting.

All DVI/HDMI transmitters will be destroyed if you connect them directly to the Amiga. You need to convert the +5V logic to +3.3V logic with appropriate converters. Some 74LV244 or equivalent devices run off 3.3V but have 5V tolerant inputs.

I have never run a DVI interface at less than VGA (640x480) resolution so I can not say for sure if it will work with say Hires (640x256) or low res (320x256) amiga displays.

For the I2C interface, connect up a microcontroller with one of these ports. For DVI devices, this is used to read the Extended Display Identification Data (EDID) PROM in the monitor and set up natural screenmodes and refresh rates. You can also use the microcontroller to program the DVI chip via I2C.

I hope this gives you a few ideas.

Ian

[Stedy]

Eriond,
If you have the SiI9134 datasheet, check if it supports RGB 8:8:8 input (24 bit video)?

The product brief is unclear if it supports this video format.

For the I2C interface, I'll tell you a little of what I will soon be experimenting with. I am playing with Microchip PIC microcontrollers for a non-amiga related application and will be using the I2C bus. These devices can send/receive the I2C bus easily. To make development easier, you can buy a I2C monitor/probe, the PICKit Serial Analyser. Look this up on the   Microchip website.
You can bit bang the parallel port but a microcontroller costs  only a few pounds/euros/dollars and takes care of it.

I think we are all getting screen resolutions and lines of video mixed up.

A PAL Amiga outputs 576 lines of active video, regardless of if the resolution is 320x256 pixels or 640x256 or 640x512 pixels. An NTSC Amiga will output 480 lines of video (I forget the resolutions of NTSC Amigas). There will be a scaling factor to fit for example, 256 pixels high across say 512 lines of video. Likewise 320 pixels of data will be stretched to fill the 52us active video time of a line of video. If there was less data/pixels you would see black borders on an analogue TV.

Likewise, VHS video is only 315-325 lines of video data but scaled to fit a full TV display.

Tomorrow night, when I return to the workshop  :-) I will take a look at the Amigas video signals on my oscilloscope.

What I'm saying is that regardless of the pixel resolution, there should still be 576 lines of video for a TV display and enough video data to fill the 52us active video line. This in turn should be enough video data to satisfy the 25MBit/sec requirement of DVI/HDMI.

On one of our systems at work, we convert PAL (768x576 pixels or 576 lines of video) to DVI with no issues.

Lisa has a 28MHZ clock input on pin 25. On pin 43 is the 28MHZ clock output to the Video DAC.
Either the Sync on Green (SOG) on pin 26 or the global, CSYNC output is used to sync the BT101/ADV101 video DAC.

Hope this helps.

If I get the time tomorrow, will measure the Amiga RGB video outputs with my scope.

Ian

[Stedy]

Eriond,

Using a microcontroler for the I2C is good! As well as connecting the I2C bus to the HDMI device, you will also need to connect it to the HDMI connector. This allows you to read the I2C EEPROM in the TV and find out what display modes it supports. The serial port or clockport would be easy interfaces for the control interface.

If you bit bang the I2C bus, you must remember that the bus is open collector, so when finished with the bus, set the clock/data pins to input. Not doing this can hang the bus.

From a quick web search of suppliers, it seems that all HDMI devices are under NDA. Given any thought to making a DVI port and using an off the shelf DVI to HDMI adaptor?

DVI devices are openly documented and easier to purchase.
Have you enquired about purchasing small quantities of HDMI devices from either Silicon Image or Analogix?
If you can not purchase them, not much point in doing the design. Just trying to be practical here.

Good luck

Ian