Jump to content
IGNORED

Horizontal Homebrew expansion PCB orientation?


brain
 Share

Recommended Posts

Being new to the TI, I noticed that things like CF7, NanoPEB, and Matt's 32k expansion (http://atariage.com/forums/topic/254502-32k-expansion-for-the-side-port-released) are oriented vertically.

 

Is there a specific reason?

 

I ask because it looks like Matt is suggesting a new expansion option (ala Arduino shields), but I am wondering if a horizontal orientation might be better for that

 

  • horizontal would allow the stacking to go upwards, while the right side of the initial board could have the original connector on it (for compatibility), at no additional cost.
  • It looks like, according to standard Arduino stacking, one could put 4 boards together in the height of the current 99 4/a If one puts boards underneath, another 2 could be added, for 6 total.
  • ON Matt's expansion, the bare pins extend to the right side of the PCB. That seems problematic.
  • If a horizontal width of 4.5" was acceptable, the main horizontal board could have a second PEB connector out the back for the firehose. 4.5" is a bit long, though, so maybe that's too long to consider

 

Don't want to take away from Matt's project or his idea, just wondering as it seems like a precedent has been set...

 

Jim

Link to comment
Share on other sites

One of the main issues with a horizontal expansion is the connector to the console. It is relatively easy to get straight through 44-pin connectors (with .100 spacing). Some RA connectors in this size are also out there, so you could mangle one to make a horizontal connector (I've done that), or you could get some of the correct saddle-style connectors (I've done that last one for the PEB Splitter boards). The big problem there is price and minimum buy quantities: you have to buy something like 14 of the saddle-style connectors at a minimum, and they are about $9 a pop, IIRC. Quantity pricing doesn't help much either. . .

 

With all of those issues, vertical is just a whole lot easier to realize. . .unless, like with the PEB splitters, horizontal is the only reasonable solution. Just note, the cost to go horizontal is a lot higher. . .

Link to comment
Share on other sites

One of the main issues with a horizontal expansion is the connector to the console. It is relatively easy to get straight through 44-pin connectors (with .100 spacing). Some RA connectors in this size are also out there, so you could mangle one to make a horizontal connector (I've done that), or you could get some of the correct saddle-style connectors (I've done that last one for the PEB Splitter boards). The big problem there is price and minimum buy quantities: you have to buy something like 14 of the saddle-style connectors at a minimum, and they are about $9 a pop, IIRC. Quantity pricing doesn't help much either. . .

 

With all of those issues, vertical is just a whole lot easier to realize. . .unless, like with the PEB splitters, horizontal is the only reasonable solution. Just note, the cost to go horizontal is a lot higher. . .

But, you can use the straight through connectors on the end of a PCB, I do it all the time. Is that the only reason?

Link to comment
Share on other sites

this is why:

 

ti994-sidecars.jpg

I understand, but I'm not suggesting people continue to horizontally expand. Matt (and others) are suggesting a stackable Arduino-like expansion system, and I am wondering if it would be a better idea to create a single "base" that has the requisite connectors on both sides, but has Matt's connector on top, and the boards stack upwards.

 

JIm

Link to comment
Share on other sites

I understand, but I'm not suggesting people continue to horizontally expand. Matt (and others) are suggesting a stackable Arduino-like expansion system, and I am wondering if it would be a better idea to create a single "base" that has the requisite connectors on both sides, but has Matt's connector on top, and the boards stack upwards.

 

JIm

 

Si.. well the other thing is you don't have to run all 32 lines as far.. just a short way

Link to comment
Share on other sites

The real problem with getting the straight connectors attached to the side port horizontally is that the regularly available ones have super-short pins. If I could find the 44-pin ones with the longer, wire-wrap pins, no problem--but they are just as hard to find (and as expensive) as the saddle-style ones are. The only commonly available 44-pin connectors that have pins long enough to use ar the right-angle connectors, and it was a serious pain getting one of those properly formed to use as a horizontal edge connector.

 

44-pin connectors of the proper land spacing are just not that common, so a lot of the connector types you can easily find for other pin counts are really difficult. . .and most of the 44-pin connectors that are out there and readily available use .156 spacing, which is useless here.

 

I hope you do get something working though--I'm just identifying the point where the most difficulty will arise in the hope that you find a way around it that I didn't.

Link to comment
Share on other sites

Hey, that 99/4 train is missing one sidecar (probably the Video Controller, as the fourth one is probably the p-Code box). I need to put mine together again with all of them in the line to show how massive that thing really was. . .too bad I don't have a Denali Data Backer Buss to rotate it around behind the console. . .I wonder if one of the PEB extender cables would work just as well there?

  • Like 1
Link to comment
Share on other sites

The real problem with getting the straight connectors attached to the side port horizontally is that the regularly available ones have super-short pins. If I could find the 44-pin ones with the longer, wire-wrap pins, no problem--but they are just as hard to find (and as expensive) as the saddle-style ones are. The only commonly available 44-pin connectors that have pins long enough to use ar the right-angle connectors, and it was a serious pain getting one of those properly formed to use as a horizontal edge connector.

 

44-pin connectors of the proper land spacing are just not that common, so a lot of the connector types you can easily find for other pin counts are really difficult. . .and most of the 44-pin connectors that are out there and readily available use .156 spacing, which is useless here.

 

I hope you do get something working though--I'm just identifying the point where the most difficulty will arise in the hope that you find a way around it that I didn't.

 

Actually, I have previously solved both problems, as I produce a cart expander for the C64, which uses 22/44 .100 connectors for its cart port. So, I buy them by the 1000s (yep, because a cart expander uses 4 of them at a time, so it's not as bad as it seems). And, the pins are PC pins (as you imply), but they are long enough to bend and solder to the PCB:

 

IMG_0120_detail.jpgclick image upload

 

This is part of a larger item, called XPander-3, which you can find pics of anywhere.

 

Anyway, I also sell the connectors, as I understand they are a bit tough to find a time, especially without ears.

 

Thus, I am confident I can solve the connector concern, but it seems like there might be more issues.

Edited by brain
  • Like 1
Link to comment
Share on other sites

I thought about doing something like that... But ultimately, I wanted as few 'tricks' involved in construction of the 32k board as possible. I will at some point want to quit making them, but at some point make it completely open for others to build.

I also don't know what we'll want to hook up to that thing, so I wanted to invest minimally in the vaporware side of it. Nothing is/was designed for the The HAT/SHIELD/CAPE style expansion, so there are no requirements to base a design off of. My design was around keeping the 32k pcboard as cheap as was worth the effort. 32k for the masses. If I had done a horizontal layout with the edge-connector style it would have added a couple square inches to the board. Inches == cost.

Something I like about what I've done is it's just no big deal for small boards to attach to the right, using stacking headers ( probably the extra tall ones, but hey, it'll work ) or if your device is more of a beast than that, a ribbon cable will work.

The precedence I'm trying to set is 'uncomplicated & accessible'.

But hey, you have a different idea, prototype it up and see what sticks! It's all about fun.

-M@

  • Like 3
Link to comment
Share on other sites

That looks almost exactly like the first iteration of the side port splitter board I did. I removed the possibility of adding the stacking connector because no one (back then) expressed interest in using it for anything. One note: I'm not sure how long you made the lands for the 44-pin to attach too, but that connector goes relatively far inside the console, so you might need more depth there than you've initially calculated. You are also probably better with the 4x4.5, as that will let you connect two firehose cables to the card (and that configuration is actually very possible with all of the expansion cards out there to choose from--sometimes you need more than seven configurable slots, and the TI supports up to 16 of them based on the OS hooks already in place).

 

In using connectors with the short pins--it is all about long-term stability. The short pins don't really provide a large enough surface area at the point they meet the board to make a good long-term mechanical connection. That was the main reason I avoided using them that way. The side port connector area takes a lot of stress.

Link to comment
Share on other sites

That looks almost exactly like the first iteration of the side port splitter board I did. I removed the possibility of adding the stacking connector because no one (back then) expressed interest in using it for anything. One note: I'm not sure how long you made the lands for the 44-pin to attach too, but that connector goes relatively far inside the console, so you might need more depth there than you've initially calculated. You are also probably better with the 4x4.5, as that will let you connect two firehose cables to the card (and that configuration is actually very possible with all of the expansion cards out there to choose from--sometimes you need more than seven configurable slots, and the TI supports up to 16 of them based on the OS hooks already in place).

I'll micrometer the conn, but you are almost certainly right. the conn I have just aligns with the edge of the console, but that does not allow for a case, wiggling it out, etc.

 

The 4.5 x 3 will also support two PEBs. I *like* the 4x4.5 aesthetically, but I'll probably run a small 5 up batch of the boards just to see.

 

On expansions, I have a couple of options, one being Ethernet. It seems like that's a pretty easy one to put in place, given that I have HW experience there already.

 

My thought would be to create a PEB card with the same connector, so one could put the cards in the PEB or here. A small carrier with a 44 pin edge and the headers would offer lots of combos.

 

Out of curiosity, you note a first version of the splitter board. Is there a pic? Why did you revise it?

 

Jim

Edited by brain
Link to comment
Share on other sites

On the initial reason for the revision, I had the edges of one of the connectors set too narrow (by about 2mm), so it was possible for pins to short out (I skipped my usual final QC step while doing the layout, and it bit me). ;) I built two of them for testing--and that was all, The extra connector didn't have a real purpose back then (no one had these nice new sideport thingies available or planned), so I asked the folks who wanted the board and none were really interested in it. Since my original plan was only to do one run of them anyway, I dropped the extra connector in the final board.

 

BTW, don't try to connect anything but a Speech Synthesizer to the 44-pin connector on my upcoming Speech-in-the-PEB board, as it won't work. Only the lines necessary to the SS are present there.

Link to comment
Share on other sites

I did some measurements, and figured out how to "hide" part of the firehose conn behind the console by pushing the PCB back so it is towards the back edge of the case. As it currently stands, the PCB is 3.5" by 4.0", and offers almost 9 sq inches of design space

 

I created a box around the design to show exterior case dimensions. I left .15" for walls, which is > 1/8"

 

I added a second header, to create a foundation for a stacked card, but it was just a copy of the other one. 2x18 stackable headers are the norm in Arduino-land, so and other options are much more expensive. I thought perhaps a 2x18 for the signals and the 2x3 or 1x6 for power/ground would work for the stack.

 

revised.png

Link to comment
Share on other sites

Learning as I go:

 

daughterboard.png

main.png

 

I think I am comfortable enough with the main board to run a few of them (gotta get the order in before Chinese New Year), but it looks like it'll take some time to understand the RS232/Parallel port board.

 

I only put 512kB of FLASH and 1MB of SRAM on the main board, but I thought that would be somewhat useful.

  • Like 1
Link to comment
Share on other sites

I kind of like the mini-tower idea. The first card that plugs into the TI would simply be a platform/backplane. All these new compatible devices would use modern connectors in the same exact spot for compatibility, and stack up vertically. Along the way matching 3D cases could be made and stacked up like Legos. One would only need to purchase the components they want as they are released like a SAMS, an RS-232 or variant, a FDC, or even an SD card based SSHD, etc. Basically the sky would be the limit, albeit about an inch and a half at a time.

 

A set and open design from the Gurus here would encourage adoption and easily take us into the next decade.

Link to comment
Share on other sites

  • 2 weeks later...

OK, main board partially soldered, and test fit. Looks good (might add just a bit to depth, as firehose just touches case).

 

IMG_7715.jpg

IMG_7716.jpg

 

I'll solder on the 1MB SRAM next, and then finish the SAMS emulation in the CPLD. Looks like I'll need to ping some folks on how to test.

 

Jim

  • Like 1
Link to comment
Share on other sites

Well, I'm a very new user, and I just have just my black 4a, peb, 32kB RAM, RS232, and disk. Nothing else. Without more, I don't think I can load data from disk, though I could be wrong.

 

Jim

 

Dude, you're in luck! Since you have a P-Box, you have a couple of options.

 

1) There is the Lotharek HxC Floppy Emulator with this gadget, you can download TI

goodies to your PC, save them on an SD card and then plug them into the TI!

 

2) If you go the the route above, you can increase your data storage space with an

inexpensive modification to the TI floppy disk controller.

 

If that route does not interest you...

 

3) There is the HDX modification when effectively turns your PC into a hard drive

for the TI.

 

And if you don't like the modification route and you don't care about loading the programs off of disk..

 

4) There is the amazing FlashROM 99 cartridge. It's another way to transfer stuff to run off the TI with

stuff downloaded from the Internet. Let me tell you, the guys here have been REAL BUSY, they've

converted a massive amount of programs to run off that thing and you can get them here.

 

HAVE FUN!!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...