Atari Portable Project

[+selgus]

When I decided to add the cartridge port to my portable, I needed to re-design how I would power the device, as the current lipo setup would no longer work. I originally had a standard lipo cell that sat underneath the motherboard and the enclosure bottom. With the cartridge port, the space had change significantly and I would either need to increase the thickness of the device, or try something different.

 

So, the "something different" solution. I first CAD designed what a lipo pack could be shaped, to fit the available space:

 

 

Then I search for a factory that could manufacture lipo packs to my specifications (single cell, 3.7V, 10,000mAH, JST-2 connectors and my dimensions). So here are the results being shipped to me as I type:

 

 

They look great, just need to test them for fit and check how long the can drive my motherboard and LCD between charges.

 

One nice side effect of going this route, is now I have a official Lithium Polymer battery, 8mm thick, with protection circuitry and discharge rate for my project, that I can get in any quantity.

 

[+scorpio_ny]

4 minutes ago, selgus said:

When I decided to add the cartridge port to my portable, I needed to re-design how I would power the device, as the current lipo setup would no longer work. I originally had a standard lipo cell that sat underneath the motherboard and the enclosure bottom. With the cartridge port, the space had change significantly and I would either need to increase the thickness of the device, or try something different.

 

So, the "something different" solution. I first CAD designed what a lipo pack could be shaped, to fit the available space:

 

 

Then I search for a factory that could manufacture lipo packs to my specifications (single cell, 3.7V, 10,000mAH, JST-2 connectors and my dimensions). So here are the results being shipped to me as I type:

 

 

They look great, just need to test them for fit and check how long the can drive my motherboard and LCD between charges.

 

One nice side effect of going this route, is now I have a official Lithium Polymer battery, 8mm thick, with protection circuitry and discharge rate for my project, that I can get in any quantity.

 

This is amazing! It never ceases to amaze me how many talented people are on this forum!

[+selgus]

Just was able to get back to this project and started to assemble one of the final motherboards.. has lots of passives spread out over the PCB, so about half way complete soldering them by hand..

 

 

And the battery fits nicely in the lower enclosure, so in the final phases now..

 

[+selgus]

Almost there.. still have a few capacitors to install, along with the 512K SRAM extended memory chip and I couldn't find my precision 20P narrow DIP sockets.. so needed to order some more. Also have my w65c02s Sally-replacement board in the photo..

 

[+selgus]

Now really almost there..

 

I still need to burn the GAL and program my replacement OS I wrote (which used the XEGS code as a base) into my flash ROM. Also, I haven't soldered in the 40-pin precision sockets yet, as I want to do a bit more testing (as there are components that live under those sockets).

 

This thing is a pain to solder by hand.. definitely a labor of love..

 

[magnusfalkirk]

WOW! This is one awesome project! I'm almost afraid to ask, would you be willing to build one of these for other people and how much would you charge for it? I've just recently gotten into Atari 8-bit computers. Have an Atari 400 a friend gave me and bought an Atari 800xl from eBay. Also have the S-Drive Max and a Side3 cartridge. Plus a TON of images I download from the web and several cartridges I bought from eBay.

 

magnus

 

P.S. Happy Thanksgiving to everyone on AtariAge.

[+selgus]

On 11/24/2022 at 2:05 PM, magnusfalkirk said:

WOW! This is one awesome project! I'm almost afraid to ask, would you be willing to build one of these for other people and how much would you charge for it?

Thanks, very kind.

 

To be honest, I am not sure what I am ultimately going to do with this project. I've had a number of people reach out to me, letting me know they would like one. I could do what @mytek does with his projects, and just release all the files so people could build their own (though this is a bit more challenging to assemble, given all the SMD parts, etc.).

 

As to cost, one of the things I wanted to do with this project, is use original, harvested parts from an actual ATARI, when appropriate. ATARI's back then were all thru-hole parts, so all the passives are not originals and SMD. So big part of the cost is the XEGS donor motherboard for the custom chips, SIO and joystick ports, crystal, etc. Then there are all the custom parts for this build.. the lipo battery and boost power circuit, along with the charging and battery level meter components, and on and on.

 

I don't even want to mention how much time and money I put into the R&D here, but that is why we do things like this.. it's fun, it's challenging and it's a hobby. Not a business for me. So long way of saying, still don't know what happens next. I do know I have some good friends that I will be building some units for, and when I order PCBs, I never do just one.

[magnusfalkirk]

1 hour ago, selgus said:

Thanks, very kind.

 

To be honest, I am not sure what I am ultimately going to do with this project. I've had a number of people reach out to me, letting me know they would like one. I could do what @mytek does with his projects, and just release all the files so people could build their own (though this is a bit more challenging to assemble, given all the SMD parts, etc.).

 

As to cost, one of the things I wanted to do with this project, is use original, harvested parts from an actual ATARI, when appropriate. ATARI's back then were all thru-hole parts, so all the passives are not originals and SMD. So big part of the cost is the XEGS donor motherboard for the custom chips, SIO and joystick ports, crystal, etc. Then there are all the custom parts for this build.. the lipo battery and boost power circuit, along with the charging and battery level meter components, and on and on.

 

I don't even want to mention how much time and money I put into the R&D here, but that is why we do things like this.. it's fun, it's challenging and it's a hobby. Not a business for me. So long way of saying, still don't know what happens next. I do know I have some good friends that I will be building some units for, and when I order PCBs, I never do just one.

Thank you for your answer. I've enjoyed reading through your posts about this. Which ever way you decide to go with this it's a great project and congratulations on getting close to the end.

[+selgus]

I haven't talked much about the display I am using on the portable. I was thinking of starting a thread specifically for it, but its not too complicated so I'll just leave it here.

 

I'm using one of the those automotive backup camera's displays, that you can get on Amazon or eBay for between $15 to $20 US. I'm using a 5" version, but they do come in multiple sizes.

 

I've bought multiple displays at this point, and they come from all different vendors, but looks like they all share very common (but not exact) architectures. Things to remember, they are made for automobiles, so they expect from 12V to 24V inputs. Most of them also take 2 composite inputs, and the controller will look for signals on the two video inputs and display when one is active.

 

Here are a few of the different controllers inside the displays:

 

    

 

 

I had to reverse engineer these boards, and like I mentioned, they are all similar. First, they take in 12V, so there is a DC converter to go from 12V down to either 5V or 3.3V. From what I could figure out is each of the controller ICs seem to take 3.3V, but there are other functions on the PCBs. There is also a backlight, that has its own DC converter and some of them take 3.3V, but some take 5V. So the first stage DC converter will either take the 12V down to 5V, to feed into the backlight DC boost circuit (they take their own voltage, sometimes as high at 18V), and then they have another DC converter to go from 5V to 3.3V.

 

The PCBs usually have these different functions grouped in sections on the board. You can find the first stage VIN (voltage in) by following the input wires (there will normally be a POS (red), NEG (black) and video 1 and 2 (green and white). Each DC converter will have diode, a IC, a large electrolytic capacitor and some filtering caps and an inductor. The first stage cap will be something like 25V to 35V max, and the other stages will be 6V to 10V normally, so a quick way of locating where these different functions are on the board.

 

Since the ATARI Portable runs off a single LiPo that puts out 3.7V, and I use a step-up converter to supply 5V (and 3.3V, if needed by the video display.. more on that later), you need to bypass the first step on the controller. Here is what I did on one of the display boards I am using for the ATARI Portable..

 

 

I actually removed all the components for the first DC converter and wired the output pin of the IC to the VIN to the board. I figured out the circuit by first using a multimeter when no power is being supplied to it, and just figured out what was connected to what. Then I powered the board, gave it a video input signal and measure voltages at different points on the board, to be able to create a basic schematic of the controller board. So now this controller board will function correctly with 3.3V on its VIN.

 

On my ATARI Portable, I have a built-in jumper that will select if 5V or 3.3V is directed to the 3-pin video port (VIDEO, NEG, POS). This way I can use many of these backup camera displays, no matter if they expect 5V or 3.3V after the first stage.

 

Since the display does slide up and down, I have a flexible cable that connects the display to the portable, and that is the small PCB I created, at the bottom of the photo. It just has the connector for the flexible cable and a 3-pin heasder.

[macsonny]

20 hours ago, selgus said:

I haven't talked much about the display I am using on the portable. I was thinking of starting a thread specifically for it, but its not too complicated so I'll just leave it here.

 

I'm using one of the those automotive backup camera's displays, that you can get on Amazon or eBay for between $15 to $20 US. I'm using a 5" version, but they do come in multiple sizes.

 

I've bought multiple displays at this point, and they come from all different vendors, but looks like they all share very common (but not exact) architectures. Things to remember, they are made for automobiles, so they expect from 12V to 24V inputs. Most of them also take 2 composite inputs, and the controller will look for signals on the two video inputs and display when one is active.

 

Here are a few of the different controllers inside the displays:

 

    

 

 

I had to reverse engineer these boards, and like I mentioned, they are all similar. First, they take in 12V, so there is a DC converter to go from 12V down to either 5V or 3.3V. From what I could figure out is each of the controller ICs seem to take 3.3V, but there are other functions on the PCBs. There is also a backlight, that has its own DC converter and some of them take 3.3V, but some take 5V. So the first stage DC converter will either take the 12V down to 5V, to feed into the backlight DC boost circuit (they take their own voltage, sometimes as high at 18V), and then they have another DC converter to go from 5V to 3.3V.

 

The PCBs usually have these different functions grouped in sections on the board. You can find the first stage VIN (voltage in) by following the input wires (there will normally be a POS (red), NEG (black) and video 1 and 2 (green and white). Each DC converter will have diode, a IC, a large electrolytic capacitor and some filtering caps and an inductor. The first stage cap will be something like 25V to 35V max, and the other stages will be 6V to 10V normally, so a quick way of locating where these different functions are on the board.

 

Since the ATARI Portable runs off a single LiPo that puts out 3.7V, and I use a step-up converter to supply 5V (and 3.3V, if needed by the video display.. more on that later), you need to bypass the first step on the controller. Here is what I did on one of the display boards I am using for the ATARI Portable..

 

 

I actually removed all the components for the first DC converter and wired the output pin of the IC to the VIN to the board. I figured out the circuit by first using a multimeter when no power is being supplied to it, and just figured out what was connected to what. Then I powered the board, gave it a video input signal and measure voltages at different points on the board, to be able to create a basic schematic of the controller board. So now this controller board will function correctly with 3.3V on its VIN.

 

On my ATARI Portable, I have a built-in jumper that will select if 5V or 3.3V is directed to the 3-pin video port (VIDEO, NEG, POS). This way I can use many of these backup camera displays, no matter if they expect 5V or 3.3V after the first stage.

 

Since the display does slide up and down, I have a flexible cable that connects the display to the portable, and that is the small PCB I created, at the bottom of the photo. It just has the connector for the flexible cable and a 3-pin heasder.

This is such a cool project. First time I've seen the thread. I'll be following closely now!