The F18a DIY alternative with HDMI :)

[Duewester]

4 minutes ago, Hans23 said:

The test run of my SMD version of the board arrived today, and I think it looks pretty good.  It fits into the TI-99/4A perfectly and height-wise, it might even go under the shielding, although I have removed that from all of my consoles and can't really try.  I'll actually try this on the weekend and will send a pull request as soon as I know that it works.

 

 

 

That is a tight fit indeed. 

[retrocanada76]

4 hours ago, Duewester said:

@retrocanada76, I've been thinking it probably has something to do with timing. The 9900 in a Ti is different from the (I think it's one)Z80 in the Nabu. I mean the data bus is only one element of the programming but if the timing is out of whack...

So I just commited a faster power on on github. Sync your repo, rebuild and reflash your unit. Other than that is having on TI99 for testing.

[retrocanada76]

@Duewester did you try my new code ? just pull my changes, rebuild and re-flash. it might boot faster. I was putting a half second delay to start now it's just a manner of few clocks.

[retrocanada76]

16 hours ago, Hans23 said:

The test run of my SMD version of the board arrived today, and I think it looks pretty good.  It fits into the TI-99/4A perfectly and height-wise, it might even go under the shielding, although I have removed that from all of my consoles and can't really try.  I'll actually try this on the weekend and will send a pull request as soon as I know that it works.

 

 

 

@Hans23 wow, that's surgical precision! Try my latest push to the repo i made the power on faster.

 

Aynway if the board does not work, can you try using a scope to see if the signals are coming to the TANG ?

here the cheat sheet for the pins:

I need you to check if the ~CSW is actually strobing. ~CSR is used when the CPU reads from the VDP. These signals come from the LVCs, if not strobing, check both ports on them. Who knows the TI might be electrically different.

 

 

Edited May 20, 2023 by retrocanada76

[retrocanada76]

if strobing then do the regular diagnostic: check reset and int lines and the data lines.

[retrocanada76]

5 hours ago, retrocanada76 said:

@Duewester did you try my new code ? just pull my changes, rebuild and re-flash. it might boot faster. I was putting a half second delay to start now it's just a manner of few clocks.

@Duewester can you take a close picture of the both sides of your populated board (without the tang on it) ?

[Duewester]

13 hours ago, retrocanada76 said:

@Duewester did you try my new code ? just pull my changes, rebuild and re-flash. it might boot faster. I was putting a half second delay to start now it's just a manner of few clocks.

Good morning. @retrocanada76. I've been away from the project (have to give family some time on occasion🙂)

I'm gonna start with your first idea and sync up my repository to yours (I hope- I'm not real good with GitHub). I'll start with that and let  you know how things are going.

[Duewester]

14 hours ago, retrocanada76 said:

@Duewester did you try my new code ? just pull my changes, rebuild and re-flash. it might boot faster. I was putting a half second delay to start now it's just a manner of few clocks.

OK, we're getting somewhere o9n this. When I turn on the PC with the HDMI connected, I get this boot screen.

 

HOWEVER! When I turn on the PC with HDMI disconnected and then connect after a second or two - Two beeps from a remote speaker I have connected.

I get This.

I can press a key and I get the Select screen.

When I left everything connected and cycled power to the unit it came up working. Good news, but bad news followed.

When I tried cycling it again I got a white screen and a constant tone.

Different power cycles provided different results. Different tones, boot screen sometimes with or without tones.

But as long as I power on the PC with the HMDI disconnected, wait for the beeps, and then connect HDMI - it works.

 

 

[Duewester]

So maybe, wrong direction with clock cycles?

Here's part of the timing chart.

 

I'm not very good at this but looks to me time you need 6 or 7 clock cycles.

And here

they talk about a 100 nanosecond wait for the noise to clear.

 

So, looks to me like 100 nanoseconds and 6 clock cycles are important numbers.

[retrocanada76]

Well at least some progress. The signals are getting into the board. It's is more a timing boot process.

 

So I just pushed another change to the github. Now I start gromclk and cpuclk right after the boot just like the f18a does. I was holding up on the power on reset for the rest of the board. 

 

So try now and see if it boots stand alone.

 

otherwise only a hands on with a scope to better understand what's going on.

 

if still doesn't work make sure your project is set to 25Mhz loading rate. Just open Project -> Configuration -> BitStream. Loading rate should be 25 (it's the maximum for the board)

 

[retrocanada76]

Have you populated the VGA breaker ? I would like to know if it works from the VGA straight on. Also, try a different HDMI monitor if possible. Some TV or monitors keeps poking the I2C info from the HDMI sink, I don't know if this could cause any issue but you see a led blinking constantly. But hey, we are getting progress here :D. I will be off for the rest of the day returning home later. Good luck

[Duewester]

2 hours ago, retrocanada76 said:

Well at least some progress. The signals are getting into the board. It's is more a timing boot process.

 

So I just pushed another change to the github. Now I start gromclk and cpuclk right after the boot just like the f18a does. I was holding up on the power on reset for the rest of the board. 

 

So try now and see if it boots stand alone.

 

otherwise only a hands on with a scope to better understand what's going on.

 

if still doesn't work make sure your project is set to 25Mhz loading rate. Just open Project -> Configuration -> BitStream. Loading rate should be 25 (it's the maximum for the board)

 

Loaded the changes.

Same results - Tone with eventual boot screen if plugged in while starting. Works if plugged in after pc bootup.

Verified the configuration is same as above.

[Duewester]

2 hours ago, retrocanada76 said:

Have you populated the VGA breaker ? I would like to know if it works from the VGA straight on. Also, try a different HDMI monitor if possible. Some TV or monitors keeps poking the I2C info from the HDMI sink, I don't know if this could cause any issue but you see a led blinking constantly. But hey, we are getting progress here :D. I will be off for the rest of the day returning home later. Good luck

I will build vga board.

I have used two TV's. One very old and one about 5 yrs old.

Tang light does not come on if hdmi is plugged in during boot.

[Duewester]

I assembled a VGA board.

Plugged in VGA and powered on the pc. Beep and up it came. Cycled power several times and it came up every time.

The HDMI cable is not plugged in.

Turned on PC with VGA unplugged. Beep. Plugged in VGA - screen came up.

While PC still on - Plugged HDMI and changed TV to HDMI and screen came up.

Cycled power with HDMI selected and PC came up once and then toned on subsequent turn on.

Selected VGA with HDMI still plugged in but power off to PC. Turned on PC and came right up. Selected HDMI and screen was up.

VGA on a Monitor and HDMI on TV - power on PC and Tones with eventual F18a boot screen on both .

Turn off HDMI at TV and PC but all still connected. Power up PC and VGA monitor comes on.. Select HDMI on TV and screen comes on.

 

Have to say, the colors are more brilliant on HDMI than VGA but that could be a VGA monitor tuning thing.

 

So it looks like an HDMI timing issue to me. As longs as there is no place for HDMI signal to go on bootup, it works. But if you have HDMI connected and selected (at TV) when powering up the PC, fault.

[retrocanada76]

Try a different hdmi cable as well.

the usb-c is not connected right?

when you mean pc you talking about the TI99 right? Not a pc connected through usb-c.

[retrocanada76]

I could try delaying the dvi interface

[Duewester]

USB-c not connected.

PC is Ti.

I gotta look around for another HDMI cable. Almost every one I have is full size on one end and Micro or Mini on the other ( I play with Raspberry Pi 's of all kinds). I got a box of adapters somewhere, surely I can make up something.

[Duewester]

Well I tried a New shorter HDMI to Mini HDMI cable with Adapter.

I thought we were onto something but after about three TI power cycles it was back to a long tone before the F18a boot screen.

Dangit.

I tried different HDMI ports on TV and with and without my flat cable jumper.

I do see this though, if I leave the TI off for a while (a minute or so) and then power it up with the HDMI connected- it boots up perfectly about 3 out of 5 times. The longer the power off interval, the better the chance it comes up.

Found another new HDMI cable that is short but standard size. Still no joy with boot up. At least I have a short cable now that doesn't make a mess of my workspace.

 

Scratch that 3 out of 5 thing. It's back to the same ol' same ol...

Edited May 20, 2023 by Duewester

[retrocanada76]

Did you try connecting straight to the tang? You had this flat extension

[retrocanada76]

There is a tiny little jumper on tang 9k closer to the hdmi. See if you are capaple of shorting it. Try protecting the other components with kapton tape then you apply flux and a bit of solder. Some people commented it fixed some hdmi problems with certain TVs

 

Edited May 20, 2023 by retrocanada76

[Duewester]

 

37 minutes ago, retrocanada76 said:

Did you try connecting straight to the tang? You had this flat extension

Yep. Used many combinations with and without flat cable.

[Duewester]

Shield installed. Edges taped off. HDMI flat Cable running under Fat Board. VGA connector has to be installed after shield.

 

The cover fits!

The power board isn't in and the keyboard is disconnected but the case doesn't hev to cut open on top for the board to clear even with the HDMI adapter installed.

[Duewester]

42 minutes ago, retrocanada76 said:

There is a tiny little jumper on tang 9k closer to the hdmi. See if you are capaple of shorting it. Try protecting the other components with kapton tape then you apply flux and a bit of solder. Some people commented it fixed some hdmi problems with certain TVs

 

Ooooo that's a tiny a little jumper. I have Kapton and and needle soldering iron but if I screw this up I'm down to one Tang. I think I'll hold off till tomorrow when I'm fresh to attempt this one.

[retrocanada76]

Can you test in a different Ti unit just for sake? 

[Hans23]

Today, I finally tested the SMD PCBs and it seems everything is fine with them:

 

 

The HDMI output does not, however - I just see the F18A initialization screen.  I've added the bridge near the HDMI socket just for good measure, but as the monitor could display the signal just fine, that'd not make any difference.

 

Is it possible that the HDMI initialization takes more time, making the F18A miss the initialization sequence from the TI?  I'll try to think of a way to measure this to see if it is really the case.

 

I am totally stoked that this works!  Thank you @retrocanada76 for taking on this project!