Jump to content
jedimatt42

32k expansion for the side port - released

Recommended Posts

It doesn't work at all when in that accidentally powered state. Or at least when I've done that it didn't. I think it only looks like it is on because of the LED circuit...

 

 

https://www.youtube.com/watch?v=qSxObFm69T8&feature=youtu.be

 

I dunno what I can tell ya. While the memory test fails, it seems to work fine 95% of the time. I've only had one lockup in Super Mario Brothers and I'm not sure I can attribute that to the memory expansion as it's only happened once.

Share this post


Link to post
Share on other sites

So far, with help from Stuart, we've identified a missing trace. And the bulk of the board is getting it's current only from signal levels. I don't understand why that works... probably something to do with the word 'semi' -- and I guess reality is that it only semi-works.

 

Another problem seems to be stability with the low power HCT chips. It is looking like we'll have to use external power for this. And the mod in Chris's latest newsletter would only work if you mod the console to pass more current. I will be experimenting with that.

 

--

 

I will need to add a lead to the circuit boards to match intended design. Any opinions out there on appropriate glue for physically adhering to pcboard/soldermask? I'm thinking a couple drops of gorilla glue epoxy.

 

[email protected]

Edited by jedimatt42

Share this post


Link to post
Share on other sites

External power, or draw more off the sideport than it is designed for... I'm measuring ~65mA through the memory board with the LS245 buffer chip instead of the HCT245. This seems to be the big win for stability. More testing though.

 

Anyone know if there is a physical restriction on the sideport +5v? I guess I have to open a console and see what is between that sideport pin and the actual +5v from the power supply.

 

[email protected]

Share this post


Link to post
Share on other sites

External power, or draw more off the sideport than it is designed for... I'm measuring ~65mA through the memory board with the LS245 buffer chip instead of the HCT245. This seems to be the big win for stability. More testing though.

 

Anyone know if there is a physical restriction on the sideport +5v? I guess I have to open a console and see what is between that sideport pin and the actual +5v from the power supply.

 

[email protected]

 

It's possible that this design was to discourage 3rd party development. I don't see why you couldn't tie that line in with an internal wire, straight to the PS's regulated 5v output.

Share this post


Link to post
Share on other sites

 

It's possible that this design was to discourage 3rd party development. I don't see why you couldn't tie that line in with an internal wire, straight to the PS's regulated 5v output.

 

It may be that it's possible... but thinking about the target consumer, this would eliminate the "Plug & Play" aspect of the devices design.

If an internal console modification 'was required', that would probably suppress the market some.

Share this post


Link to post
Share on other sites

 

It may be that it's possible... but thinking about the target consumer, this would eliminate the "Plug & Play" aspect of the devices design.

If an internal console modification 'was required', that would probably suppress the market some.

 

Right you are Omega. I know jedimatt is going for plug-and-play which is the whole point of his project. Hopefully he can build this to not require an external 5v source, since that complicates things too. I know the TI sidecar 32K ram had its own supply built in - does anyone know if other manufacturers' ones did too?

Share this post


Link to post
Share on other sites

all the one's I've seen did.. corcomp, TI, Tachyon systems, nanopeb/cf7 imho a power supply isn't a deal breaker long as we can get them easily and sell them with it and or provide the specs.. Either that or make a pigtail that goes to the video port with a passthrough..

 

Greg

Share this post


Link to post
Share on other sites

all the one's I've seen did.. corcomp, TI, Tachyon systems, nanopeb/cf7 imho a power supply isn't a deal breaker long as we can get them easily and sell them with it and or provide the specs.. Either that or make a pigtail that goes to the video port with a passthrough..

 

Greg

 

I like the pigtail idea. You'd just need a regulator to get to 5v, which would add another component to the board, but not too big of one.

Share this post


Link to post
Share on other sites

I have been playing with using USB chargers as power sources. A USB to barrel connector can be found relatively inexpensively.

Share this post


Link to post
Share on other sites

I have been playing with using USB chargers as power sources. A USB to barrel connector can be found relatively inexpensively.

 

That's a good idea, since those things are typically smaller than your average wall wart. You can get 500ma from USB 1.0 so I'd think any of those would work OK in terms of, although I'm not sure how clean the signal is. Since they're designed just to charge batteries, I wonder if they have much in the way of filter caps in them.

Share this post


Link to post
Share on other sites

I have been playing with using USB chargers as power sources. A USB to barrel connector can be found relatively inexpensively.

less than $4 on amazon as an add-on item... :) Just ordered one today to see how that does.

 

I've been running all day drawing 65mA off the sideport for the memory card, with the speech synthesizer attached. Between running memory tests and playing parsec, my little 4A is acting quite happy. Oh, it is powering my wireless USB keyboard and the teensy3.2 as well.

 

People have been running CF7/nanopeb off the sideport with hacks as well. I think it should be ok. But the option to provide separate power will be there.

 

[email protected]

Share this post


Link to post
Share on other sites

less than $4 on amazon as an add-on item... :) Just ordered one today to see how that does.

 

I've been running all day drawing 65mA off the sideport for the memory card, with the speech synthesizer attached. Between running memory tests and playing parsec, my little 4A is acting quite happy. Oh, it is powering my wireless USB keyboard and the teensy3.2 as well.

 

People have been running CF7/nanopeb off the sideport with hacks as well. I think it should be ok. But the option to provide separate power will be there.

 

[email protected]

 

[email protected],

 

How's the voltage with the current at 65mA? I'm wondering if it's causing the voltage to drop a little since you're technically exceeding the 50mA "limit".

Share this post


Link to post
Share on other sites

The lead from the powersupply +5v pin to the sideport +5v pin only measures 0.4 ohm. So I think the voltage drop will be just fine. And I don't think we'll be burning up the motherboard trace.

 

[email protected]

Share this post


Link to post
Share on other sites

The lead from the powersupply +5v pin to the sideport +5v pin only measures 0.4 ohm. So I think the voltage drop will be just fine. And I don't think we'll be burning up the motherboard trace.

 

[email protected]

 

lol no - no turning traces into fuses :) What I was getting at was, if the current is limited to 50ma through current regulation, then I wondered what's happening to your voltage level if you're sourcing 65ma. It may bring the voltage down inversely as you pull more current. If the voltage drops below the min required by the ICs, you might get some flaky behavior.

Share this post


Link to post
Share on other sites

lol no - no turning traces into fuses :) What I was getting at was, if the current is limited to 50ma through current regulation, then I wondered what's happening to your voltage level if you're sourcing 65ma. It may bring the voltage down inversely as you pull more current. If the voltage drops below the min required by the ICs, you might get some flaky behavior.

When I trace the path through the 4A mainboard, the +5v line seems to pass through a number of diodes along the way, but I don't see it going through any other components. At least I think they are diodes... black cylinders with no visible markings, they look like rectifier diodes, instead of switching diodes.

 

The intention:

  • run the 32k board directly off the TI sideport, play some games.
  • modify a speech synthesizer to pass the sideport power through, run the 32k board off the side of the speech, play some games.
  • Modify nothing, use a speech synthesizer, provide yourself a +5v supply for about $5 that uses the word 'regulated' in the description, play some games.

I think everything will be fine with those options.

 

[email protected]

  • Like 1

Share this post


Link to post
Share on other sites

When I trace the path through the 4A mainboard, the +5v line seems to pass through a number of diodes along the way, but I don't see it going through any other components. At least I think they are diodes... black cylinders with no visible markings, they look like rectifier diodes, instead of switching diodes.

 

The intention:

  • run the 32k board directly off the TI sideport, play some games.
  • modify a speech synthesizer to pass the sideport power through, run the 32k board off the side of the speech, play some games.
  • Modify nothing, use a speech synthesizer, provide yourself a +5v supply for about $5 that uses the word 'regulated' in the description, play some games.

I think everything will be fine with those options.

 

[email protected]

 

 

Absolutely. So many people are going to be happy with this.

  • Like 1

Share this post


Link to post
Share on other sites

 

I think everything will be fine with those options.

 

 

BT_3_excel.jpg

 

Now that everything seems to be coming together in a such a splendid manner, only one thing remains...

 

726294-736392-200.jpg a case for this most bodacious device!

Share this post


Link to post
Share on other sites

When I trace the path through the 4A mainboard, the +5v line seems to pass through a number of diodes along the way, but I don't see it going through any other components. At least I think they are diodes... black cylinders with no visible markings, they look like rectifier diodes, instead of switching diodes.

 

 

The black cylinders are ferrite rings; they help stop interference on the power supply between different parts of the circuit. The wire goes straight through the middle of them.

 

I've just measured the current drawn by a NanoPEB when modified to be powered through the side port: ~75mA 'at rest', rising to ~85mA when accessing the CF card. I've had mine connected through the speech synth for an hour or so and no smell of burning in the console or molten copper traces dripping out the bottom.

Share this post


Link to post
Share on other sites

 

The black cylinders are ferrite rings; they help stop interference on the power supply between different parts of the circuit. The wire goes straight through the middle of them.

 

I've just measured the current drawn by a NanoPEB when modified to be powered through the side port: ~75mA 'at rest', rising to ~85mA when accessing the CF card. I've had mine connected through the speech synth for an hour or so and no smell of burning in the console or molten copper traces dripping out the bottom.

 

Ferrite rings... Good to know... I thought something like that at first, but then convinced myself otherwise, probably due to bad meter contact... I thought maybe the markings 'fell' off with age :) hahah...

 

Someday I should purposefully burn a trace just to learn from experience :) I love the imagery of copper dripping out of the bottom of the encasing.

 

On a serious note, thanks for that information! That is reassuring.

 

[email protected]

Share this post


Link to post
Share on other sites

An independent testing lab (@ElectricLab) reported this morning that his initial first run of the memory test prior to the fix passed, but later runs failed. After the fix, the burnin version of the test made more than 700 successful passes without failure. :thumbsup:

 

Thank you so much for this testing!

 

I'm full steam ahead now! :)

 

[email protected]

  • Like 5

Share this post


Link to post
Share on other sites

An independent testing lab (@ElectricLab) reported this morning that his initial first run of the memory test prior to the fix passed, but later runs failed. After the fix, the burnin version of the test made more than 700 successful passes without failure. :thumbsup:

 

Thank you so much for this testing!

 

I'm full steam ahead now! :)

 

[email protected]

 

 

Glad to help, especially for such a worthwhile project. So far, we're keeping under 1085 celsius which is the melting point of copper.

  • Like 3

Share this post


Link to post
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.

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...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...