[REQ] Friendlier HDMI timing

[jeffmilstea]

Sadly, the current timing refuses to light up my only two screens at home (a TV and a monitor, both 4k LG) as well as an MS2131-based digitizer. A Dell monitor at work synched up immediately. Can anything be done, or does 512x342 constrain things too much?

I don't know if it's relevant, but I recall that doubling the MacPlus hscan rate kinda puts it within range (±3-5%?) of one of the VESA VGA timings.

(I did try the "wide" option, also without success - though I appreciated that options can be set in the .ini file, thus allowing attempts at troubleshooting even without a working screen)

[luciust]

I'm using audio extractor for external speakera, and the first thing it does to to HDMI signal is making it DVI compatible. Try it.

[jeffmilstea]

I'm using audio extractor for external speakers, and the first thing it does to HDMI signal is making it DVI compatible

Which model can you recommend? And you have used it successfully with this project?

[luciust]

I'm using this one with NanoMac: https://www.aliexpress.com/item/1005004750956100.html - audio is routed to NEC 1970Nxp speakers. It's my daily driver monitor type for Atari ST/Amiga - VGA 15KHz and DVI. NanoMac fills pixel-perfect the screeen, if I choose "wide" the screen gets... narrower :) I can recommend both monitor and this HDMI audio extractor. Needs 5V USB. Oh and it works with MySTeryNano and NanoMIG - all color and mono modes and Amiga as well. Works with VIC20 as well on Tang Nano 9K.

[harbaum]

This is a classic Macintosh. Changing the video timing would make it something else. Memory throughput and as a consequence CPU speed and especially audio are very tightly coupled to the video due to the Macs very simple hardware design. Changing the video significantly would affect all these as well. The "wide"mode actually doesn't change anything in the timing itself. It just tells the screen that it might display some borders left and right.

That's why emulators are so different. They don't actually implement any hardware. They just allow executing the original code, often bypassing certain parts of the ROM/OS to avoid having to emulate the hardware at all.

Feel free to clone and modify the project. There's plenty of room left for changes. You could use a more modern 1024x768 video mode like the original PlusToo project did and just double the pixels in both directions. This will need higher memory bandwidth and in turn also give the CPU more bandwidth. Then you'd need to decouple the audio from the video timing to make it still run at the 22250 kHz the ROM/OS expects and which is then different from the horizontal sync rate of the video. That's one reason why the PlusToo project actually ran much faster than a real Mac. My intention is to preserve the hardware as exact as possible. But it's equally well possible to implement something that improves over the real thing. But that's just not my intention.

[jeffmilstea]

I'm using this one with NanoMac: https://www.aliexpress.com/item/1005004750956100.html - audio is routed to NEC 1970Nxp speakers.

Unfortunately, this device did not make any of my HDMI displays compatible with NanoMac.

[luciust]

Strange, I'm also using this with HDMI controller for LCD screen taken out of laptop, and it works quite well - but those are quite tollerant devices. Probably anything older would work better.

[amotyka]

Any suggestions for monitor models/brands which work with this core? Unfortunately none of my 5 monitors will display anything

[vossstef]

Do you have a Mega 60k/ Console 60k or Mega 138k Pro ?
If so we could add a frme buffer in DDR3 and output compatible timing.

[amotyka]

Nano 20k using onbaord bl616 but not sure if I have a setup issue, main led starts green but turns red, does this mean an SD card issue? Mystery nano core led is also red but loads fine and display is OK, mouse works but can't get keyboard to work so can't open osd menu to check sd card

[cebelcher]

I did not have luck with any of the 8 TVs or monitors I tried tonight! A list of what works would be appreciated.

[vossstef]

@cebelcher Do you have a 60k or 138k Board (too) ? As mentioned we could add a frame buffer to output compatible timings. Only possible if we have a Board with extra DDR3 memory like the 60/138k types.

[jeffmilstea]

@cebelcher @amotyka Of the 6 monitors I tried, only these 2 at my job functioned:

• DELL U3421WE
• DELL U2717D

For home, I used the recommended solution above:

graph LR
    A[Old DVI Monitor] -->|DVI-to-HDMI cable| B[Audio Extractor Box]
    B -->|HDMI-to-HDMI cable| C[NanoMac]
    B -->|Audio Line-in| A

Loading

[jeffmilstea]

Nano 20k using onbaord bl616 but not sure if I have a setup issue, main led starts green but turns red, does this mean an SD card issue?

@amotyka I gave up trying to program the onboard BL616 and just got an M0S module. For this setup, the LEDs flash in this sequence at power-on:

• The WS2812 LED is blue briefly, then remains solid green
• After several seconds, LED2 flashes during access to the SD Card

Mystery nano core led is also red but loads fine and display is OK, mouse works but can't get keyboard to work so can't open osd menu to check sd card

This sounds like it's not getting enough power. Try connecting the Tang Nano 20k board USB-C to a powered USB hub, then connect the mouse and keyboard to the hub.

[dotsam]

Just to chime in with some notes on what did and didn't work for me here on a Tang Nano 20K using the onboard BL616:

• A Dell S2721Q monitor worked without issue (and has PiP, which is nice)
• A Dell D2319H did not work
• Also no luck with an older Panasonic plasma TV
• A Macrosilicon-based USB 3 HDMI Capture device did not work
• But finally, a JetKVM IP KVM did mostly work!
  • 

It seems to not always sync up, requiring a reboot of the JetKVM once everything is powered up, and it works much better in the "Wide" video mode than standard. It also needs to use the "relative" mouse mode which can be a little buggy, but is workable. Hopefully this info is helpful!