Best PIC for digital to analog RGB(video) for N64?

[vlad777]

Hello.

I am wanting to make RGB DAC for nintendo 64.
Like in these links:
**broken link removed**
**broken link removed**

It must have 9 digital inputs and 3 analog (DAC) outputs
and 4 digital outputs.

Can you please tell me what uC (PIC best)
would be good for this?

Many thanks.

 

[Sceadwian]

There are no micro controllers that can do what you're requesting, the chip referenced in your links was a Xilinx CPLD (programmable logic) they're nothing like micro controllers.
Given it looks like you've provided full clock specs for the input signal you could do this using discrete logic and an appropriate dedicated DAC, but it's far beyond what a micro controller is capable of.

 

[vlad777]

Yes, I was now thinking uC would be too slow for (this sRGB digital) video.
(I know the difference between prog logic, fpga and uC)

But I found: ad7226 (or tlc7226) standalone 4x latch DAC.
Do you think this + shift register (actually counter) would be good solution
or u have better idea?

Also should I go with cmos or ttl?

With this DAC, do I need amplifier like THS7314 or is 7226 enough?

ths7314 -source/sink 70 mA out.
ad7226 -minimum 2k output load.

 

[ronsimpson]

We need to understand what you want to do.
"Best PIC for digital to analog RGB(video) for Nintendo 64?"
Do you want analog output for a video game?

 

[vlad777]

I want analog RGB output on my N64, because N64s come without it.
It's called RGB mod.
And also my N64 doesnt have VDC-NUS (easy rgb mod) but has DENC-NUS(chip).

VDC-NUS (DAC only) actually has rgb outputs so it's just a matter of connecting few pins.
But because DENC-NUS is both DAC and PAL encoder it doesn't have rgb outputs, so you
have to use it's input witch is 7 bit digital sRGB.

 

[Sceadwian]

We need to understand what you want to do.

He actually posted in excellent detail what he wants to do, the second image he linked above contains the entire block diagram of the circuit he's trying to replicate.

vlad, the second image you posted (n64rgb.png) contains the block diagram for all of the discrete logic that you require, you could use discrete DAC's but they're not required as the entire matrix for an R2R DAC has been given in the image as well. It only requires a bunch of flipflops and a single shift regster with a couple of not gates.

The diagram provided shows this is done within a CPLD (except for the R2R DAC) The main difference between an CPLD and an FPGA is the number of elements and their flexibility. Neither CPLD or FPGA's are anything like a micro controller, micro controllers are processors with peripherals and I/O lines, CPLD/FPGAS are raw programmable logic.

Given the resolution required of an N64 isn't that great I don't see why you couldn't do this with discrete logic chips rather than a CPLD if you're not able to program one.

 

[vlad777]

He actually posted in excellent detail what he wants to do, the second image he linked above contains the entire block diagram of the circuit he's trying to replicate.

I am sorry to disagree with you while you are backing me up.

But I only want to replicate the result, but use different circuit
because i don't like discrete R2R ladder.


This guy did it the hard way:
https://eatenbyagrue.org/tags/n64/index.html

 

[vlad777]

After some search effort,
I found TDA8702 and TDA8772.

TDA8702 - 8-bit single channel video DAC (DIP,SMD)
TDA8772 - 8-bit three non-mux channel video DAC (SMD)
(AD7226 - TOO SLOW -8-bit 4-mux-ch DIP and SMD)

TDA8702 is ideal for experimenting because it comes
in DIP package and has low pin count (,but only one channel).

DIP for test and SMD for implementation.

Does anybody know of 8-bit video DAC with
three MULTIPLEXED channels like AD7226 BUT FAST.
Clock frequency is 50 or 63MHz (in N64).

Many thanks.

 

[vlad777]

This may be related:

https://quinndunki.com/blondihacks/?p=955

What do you think?

 

[vlad777]

update

Hello again.

This is what I have so far.

**broken link removed**


**broken link removed**



Since this mod should use nintendo video cable,
I was hoping to get sync from composite
video and signal from RGB (tda8702).

When ground is not connected to scart,
there is unsynchronized picture on tv,
but when i connect ground picture
disappears and screen is black.

Maybe I don't know something about scart?

SCART pins I am using:
(21)-GND
20-composite video in
16-RGB blanking
11-RGB green in

8-switch- I am not using.

All scart GNDs are internally
connected in tv.

Please advise?

Many thanks.