LEGO Interface A (9750/9771) – LEGO Technic Control 1 (TC1) reference/ideas thread

[amine]

On 5/21/2026 at 6:12 PM, Mr Hobbles said:

Yeah, in fact I've seen many Arduino takes on it (ie. Jorge Periera did a similar approach a few years ago), but I wanted a single self contained "product" (for lack of a better term) that didn't involve fiddling with wires, soldering, etc. It should just be similar to the original adapter boards - plug and play out of the box.
 

Sure - if Blockly spoke the protocol that BrickInterface does, it would work seamlessly. I integrated it into BrickLogo a similar way, here's a video:

 

That's actually a really good idea, indicator LED's on the board. I like it! I'll add that to the next revision. Unfortunately it takes a while, as I need to design the PCB, then get it manufactured + assembled, so there's a few weeks lead time. And of course there's a minimum order quantity lol (and like I said, annoyingly, this batch had that bootloader defect)

 

Absolutely, I just wanted a self-contained out-of-the-box ready-to-run "product" with no fiddling. I'm doing nothing new here other than building it all into a productionised designed + manufactured PCB with a nice firmware. (Though, I think combining IR + Interface A is perhaps new!)

 

It would be awesome to have this card plugged as a shield for a raspberry pie using GPIO connectors. No extra computer would be needed anymore !!!

Even a partnership would be a good idea  with the raspberry pie foundation.

That would lead to the first Lego computer. No one would have done that before !!!!

 

World First Lego computer in human history !!!!

Great great great!!!

 

 

 

Edited May 25 by amine

[evank]

7 hours ago, amine said:

That would lead to the first Lego computer. No one would have done that before

World First Lego computer in human history !!!

 

 

Ummm .... Mindstorms. :)

A case doesn't make a computer. I could take a full tower, remove the case, and easily build one from Lego instead. The computer is silicon and transistors.

 

[Mr Hobbles]

7 hours ago, amine said:

It would be awesome to have this card plugged as a shield for a raspberry pie using GPIO connectors. No extra computer would be needed anymore !!! Even a partnership would be a good idea  with the raspberry pie foundation.

LEGO and Raspberry Pi already did that by collaborating on the Build Hat. Allows you to connect four Powered UP motors or sensors to a Pi - https://www.raspberrypi.com/news/raspberry-pi-build-hat-lego-education/

Incidentally I did originally consider making this as a Pi hat, but I thought that a USB device would be more universal - not everyone has a Pi, but USB is pretty much universal. But, I still like the idea eventually! You could even put multiple Interface A connectors on it, ie. control 4 Interface A’s from the Hat at the same time.

[Toastie]

4 hours ago, evank said:

Ummm .... Mindstorms. :)

You mean before the storm hit, the mechanical computer you built, right?

You had the one that could read brick coded plates sliding through and the other reading punched cards, wasn't it? Weren't these the first LEGO computers ever?

Best
Thorsten

[evank]

22 hours ago, Toastie said:

You mean before the storm hit, the mechanical computer you built, right?

You had the one that could read brick coded plates sliding through and the other reading punched cards, wasn't it? Weren't these the first LEGO computers ever?

Best
Thorsten

LOL no, I meant the actual Mindstorms products -- RCX, etc. -- these are computers.

I think you're referring to the concept Lego introduced in the 1980 "Idea Book", #8888, which I (and I'm sure others) borrowed to make programmable machines.

However, lots of machines are programmable -- that doesn't make them computers.

My greater point in my response to Amine was that we must be careful in the word "first". :)

The course that I teach at New Jersey Institute of Technology is CS-210, Technical History of Computing. I tell students in the first lecture of the semester that the "F-word" is banned from my classroom. They can say the other one, IDGF :) but we don't say "first" because that word is subjective. Instead, I teach them about generations of computing.

Granted this forum is not my classroom.

So I was just saying that, as I see it, the Mindstorms boxes would be the (ahem) initial Lego computers.

Edited May 26 by evank

[Toastie]

1 hour ago, evank said:

However, lots of machines are programmable -- that doesn't make them computers.

Ahh - that makes total sense.

I'd love attending one of your classes, I would learn so many things, that I so care about!!! 

For my birthday, my daughters gave me a ticket for a visit to a computer museum nearby, which happens to be the world'd largest - that will be a blast. Coming up soon. It's the "Heinz Nixdorf MuseumsForum" in Paderborn. Family will join as well, but they won't see that much, because I'll radiate like an Osram 2000W incandescent light bulb ... I also got a pair of Atari socks, so I am safe on the feet as well.

Thanks a lot and all the best
Thorsten

[amine]

14 hours ago, Toastie said:

Ahh - that makes total sense.

I'd love attending one of your classes, I would learn so many things, that I so care about!!! 

For my birthday, my daughters gave me a ticket for a visit to a computer museum nearby, which happens to be the world'd largest - that will be a blast. Coming up soon. It's the "Heinz Nixdorf MuseumsForum" in Paderborn. Family will join as well, but they won't see that much, because I'll radiate like an Osram 2000W incandescent light bulb ... I also got a pair of Atari socks, so I am safe on the feet as well.

Thanks a lot and all the best
Thorsten

we should make a legoline compatible with that new interface A usb card. Do you have a solution ?

On 5/25/2026 at 5:26 PM, Mr Hobbles said:

LEGO and Raspberry Pi already did that by collaborating on the Build Hat. Allows you to connect four Powered UP motors or sensors to a Pi - https://www.raspberrypi.com/news/raspberry-pi-build-hat-lego-education/

Incidentally I did originally consider making this as a Pi hat, but I thought that a USB device would be more universal - not everyone has a Pi, but USB is pretty much universal. But, I still like the idea eventually! You could even put multiple Interface A connectors on it, ie. control 4 Interface A’s from the Hat at the same time.

We must have Legolines working with your interface card !!! 

Edited May 27 by amine

[evank]

17 hours ago, Toastie said:

Ahh - that makes total sense.

I'd love attending one of your classes, I would learn so many things, that I so care about!!! 

For my birthday, my daughters gave me a ticket for a visit to a computer museum nearby, which happens to be the world'd largest - that will be a blast. Coming up soon. It's the "Heinz Nixdorf MuseumsForum" in Paderborn. Family will join as well, but they won't see that much, because I'll radiate like an Osram 2000W incandescent light bulb ... I also got a pair of Atari socks, so I am safe on the feet as well.

Thanks a lot and all the best
Thorsten

Nixdorf is definitely on my list, if I ever get to Germany.

I've been to the museum in Silicon Valley several times.

[Bliss]

6 hours ago, amine said:

We must have Legolines working with your interface card !!! 

https://github.com/maehw/BrickLines from @maehw is a solution already but at the moment it talks to interface A through an arduino.  (Which I find already very simple and cheap).
I guess it could be adapted to this new interface when its protocol becomes avail...

[amine]

2 minutes ago, Bliss said:

https://github.com/maehw/BrickLines from @maehw is a solution already but at the moment it talks to interface A through an arduino.  (Which I find already very simple and cheap).
I guess it could be adapted to this new interface when its protocol becomes avail...

I got a Legolines french teacher book for the 9700 set scan comming this weekend probably

[Toastie]

7 hours ago, evank said:

if I ever get to Germany

If you ever get to Germany, there is a place not far from Paderborn, which happens to be our house, which happens to have a granny flat ... unoccupied when my older daughter is not visiting. Kitchen, bathroom, living room, good for two. I'll also drive you there. BBQ upon return. Emanuele (@LEGO Train 12 Volts) and his lovely family knows well about it.

Best
Thorsten

[amine]

What about creating a foundation and quickstarters for rebooting the mindstorms and robotics sets ?

Lego is not working with mindstorms anymore....

 

We can work together to make Lego great again !!!

Edited May 29 by amine

[evank]

11 hours ago, amine said:

What about creating a foundation and quickstarters for rebooting the mindstorms and robotics sets ?

Lego is not working with mindstorms anymore....

 

We can work together to make Lego great again !!!

 

 

 

 

 

This thread is limited to Interface A topics. Feel free to start a new thread for your topic.

[amine]

26 minutes ago, evank said:

This thread is limited to Interface A topics. Feel free to start a new thread for your topic.

Sorry evan that is my excess of enthusiasm...

[amine]

On 5/25/2026 at 5:26 PM, Mr Hobbles said:

LEGO and Raspberry Pi already did that by collaborating on the Build Hat. Allows you to connect four Powered UP motors or sensors to a Pi - https://www.raspberrypi.com/news/raspberry-pi-build-hat-lego-education/

Incidentally I did originally consider making this as a Pi hat, but I thought that a USB device would be more universal - not everyone has a Pi, but USB is pretty much universal. But, I still like the idea eventually! You could even put multiple Interface A connectors on it, ie. control 4 Interface A’s from the Hat at the same time.

Do you think we can add support of your adaptor in 8bits emulators ? This would allow us to use  legolines or program in basic direcly from the emulators.

I am scanning an extremely  rare "not anymore" french teacher note for the 9700 set. It has applications for many 9700 models. I am planning to translate it in english sometime during that summer. I already sent the half  to evan for review. When I finish I will release the pdf.

 

 

https://archive.org/details/lego-dacta-systemes-programmables-1

 

Edited May 31 by amine

[evank]

All of the English 9700 manuals are already online. The rarest is this one: https://archive.org/details/technic-control-i-resource-guide ... I still have a box of those LogoWriter Robotics manuals, which I need to get off my behind and mail to Michael Mulhern for scanning.

[amine]

On 5/21/2026 at 4:57 PM, Mr Hobbles said:

So it's long bugged me that out of all the LEGO electronics they've ever released, the only one that truly cannot be used on modern computers is the Interface A. All the others (ie. Control Lab, RCX, etc) have hardware compatibility through USB<>serial adapters, just requiring bespoke software to use, but the Interface A has no such option. I've had to mess with Arduinos or hack a cable. So, I thought I'd design a modern "interface board".

I designed a compact board that uses an extremely cheap CH552T micro controller that exposes a USB-C port, a 20-pin IDC connector for the Interface A (so original ribbon cables can be used, or even a replacement ribbon cable), and for the fun of it, two high-powered Infra Red LED's for Power Functions (since that also has no interface, despite a published protocol!)

It exposes a serial interface over USB-C and has a simple protocol to drive the outputs and read inputs, as well as hardware input counting.

It also has two holes spaced and sized for attaching to Technic beams and bricks with pins, so it can be affixed to a MOC.

I plan to release the schematics and firmware when it's finished, though annoyingly this first batch of assembled PCB's I ordered have a hardware bug with I need to resolve first. I had to desolver one of the resistors as it was stuck in bootloader mode. >.<

Here's a video of it running with a Python script on my mac that drives the motors on the Interface A and Power Functions IR receiver.

Can it replace an RCX infrared tower ?

[Toastie]

On 5/27/2026 at 12:04 PM, amine said:

we should make a legoline compatible with that new interface A usb card. Do you have a solution ?

Well, I don't, but @alexGS knows how to do that - he has done it with TC Logo: He has changed the I/O addresses TC Logo uses in its original configuration (dec 925/6) to that of the (DOS/IBM) serial and parallel port addresses. Both versions are available: TC Logo for the 9771 card, for the serial port, and for the Centronics/parallel port. It is somewhere above in this thread.

LEGOLines does for sure the same thing on an IBM XT: I/O on 925/926. This then needs to be traced using, e.g., DOSBox-X, then patched to the serial port. And then an Arduino with simple ser2par bit banging (@maehw's version) will do. 

All the best
Thorsten

 

[amine]

I found that someone made an Mblock extension for power function. Maybe we can make the Mblock extensions for all Lego vintage stuff.

 

https://www.pawelko.net/lego-power-functions-extension-for-mblock-5/

Edited June 8 by amine

[Mr Hobbles]

I've been working on the firmware and testing it extensively, and it's taken a while (also holidays!) but I've published the firmware + schematics/pcb + protocol docs here, if anyone wants to make their own or interface with it: https://github.com/openbrickproject/BrickInterface

On 5/31/2026 at 8:50 AM, amine said:

Do you think we can add support of your adaptor in 8bits emulators ? This would allow us to use  legolines or program in basic direcly from the emulators.

Maybe, honestly I haven't thought about that. :) If it's possible to modify DosBox or some such to intercept reads to those memory addresses, it may be possible.

If it's TC Logo you're interested in, I have a modern Logo interpreter for Lego called BrickLogo here: https://github.com/openbrickproject/BrickLogo

On 6/1/2026 at 2:40 PM, amine said:

Can it replace an RCX infrared tower ?

I've been playing with this, and _partially_ - it only has a IR transmitter, not an IR receiver, so things like reading sensors, uploading firmware (which requires acknowledgements) won't work. But things like motor control can. The issue I'm finding in my testing is that the IR LED's on BrickInterface are too powerful - it completely blinds the RCX at ranges of less than 2 meters, and even then it's unreliable. Honestly I need some time to do more testing with it.

In any case, I'm happy enough with the firmware now. :) I'll keep playing with RCX and also Legacy IR (ie. Spybotics, IR trains).

If anyone would like one of the BrickInterface's I had made, please DM me. I'm keeping 6 of the batch of 20 I had made for my purposes, so I have 14 spare. All I'd ask is you cover the cost of production (which was $6.83 per board) + shipping

Edited June 12 by Mr Hobbles

[amine]

1 hour ago, Mr Hobbles said:

I've been working on the firmware and testing it extensively, and it's taken a while (also holidays!) but I've published the firmware + schematics/pcb + protocol docs here, if anyone wants to make their own or interface with it: https://github.com/openbrickproject/BrickInterface

Maybe, honestly I haven't thought about that. :) If it's possible to modify DosBox or some such to intercept reads to those memory addresses, it may be possible.

If it's TC Logo you're interested in, I have a modern Logo interpreter for Lego called BrickLogo here: https://github.com/openbrickproject/BrickLogo

I've been playing with this, and _partially_ - it only has a IR transmitter, not an IR receiver, so things like reading sensors, uploading firmware (which requires acknowledgements) won't work. But things like motor control can. The issue I'm finding in my testing is that the IR LED's on BrickInterface are too powerful - it completely blinds the RCX at ranges of less than 2 meters, and even then it's unreliable. Honestly I need some time to do more testing with it.

In any case, I'm happy enough with the firmware now. :) I'll keep playing with RCX and also Legacy IR (ie. Spybotics, IR trains).

If anyone would like one of the BrickInterface's I had made, please DM me. I'm keeping 6 of the batch of 20 I had made for my purposes, so I have 14 spare. All I'd ask is you cover the cost of production (which was $6.83 per board) + shipping

I want one !!!!!

[amine]

Breaking news !!!

 

Lego lines Mdsos (Dutch) is on archive !!!

 

https://archive.org/details/lego-lines-educaboek

Edited June 14 by amine

[Toastie]

1 hour ago, amine said:

Lego lines Mdsos Deutch is on archive !!!

WOW!

You mean Dutch, right? When I start it up, it is in English - which is perfectly fine!!!

WRONG: It is the Dutch version, just the initial screen shows INSERT/RUN/etc. When I load a .lin program, it is all Dutch!

Sorry! 

Thank you very much for sharing & all the best
Thorsten

Edited June 14 by Toastie

[amine]

5 minutes ago, Toastie said:

WOW!

You mean Dutch, right? When I start it up, it is in English - which is perfectly fine!!!

Thank you very much for sharing & all the best
Thorsten

It is in english ? Seriously.... the primitives are also in english ?

Edited June 14 by amine

[Toastie]

11 minutes ago, amine said:

the commands are also in english ?

I don't have a manual for LEGO Lines - any idea where I can find one?

What would be a good command for trying it out?

Best
Thorsten