Minimalist Europe Card Bus (MECB) - 6809 or 6809E CPU Card v2.x and a lesson for circuit designers!

Рет қаралды 306

11 ай бұрын

This follows on from my earlier Minimalist Europe Card Bus videos.
My original (v1) 6809 CPU Card required an original internal clock 6809 or 6309 CPU.
After trying to source more CPU chips it became clear that although External clock variant 6809E CPU's were readily available, the original internal clock variants (non-E suffix), were hard to find.
For this reason I decided to redesign my 6809 CPU Card to support either internal or External clock CPUs. This is my 6809 CPU Card v2.x.
Join me as I walk through the schematic and PCB changes, and then assemble and test my first card.
This video also includes a good lesson for any young circuit designers to take note of, as we encounter some design fails along the way!
To view my earlier MECB videos, please follow the link to the MECB Homepage.
If you find this video of interest, please give it a thumbs-up, and subscribe with notifications for future videos. Thanks.
Mentioned Videos:
Minimalist Europe Card Bus (MECB) - MC6809 (or HD6309) CPU Card:
• Minimalist Europe Card...
More AliExpress Re-Marked Chips Frustration (EPROMs & 6809 / 6309 CPUs):
• More AliExpress Re-Mar...
Optimising our Retro CPU Reset Design:
• Optimising our Retro C...
Blog entry:
digicoolthings.com/minimalist...
MECB Homepage:
digicoolthings.com/minimalist...
Digicool Things on the web:
digicoolthings.com
Digicool Things on Tindie:
www.tindie.com/stores/Digicoo...
Video production setup:
Camera (overhead): Sony ZV-E10 (captured at 4K 24fps)
Camera (other): Logitech Brio 4K (captured at 1080p 60fps)
Eakins Trinocular + Eakins 3700W Camera (1080p 60fps)
Mic: Samson C01U Pro USB
Lighting: Double-row 8520 LED 6000K strip lighting
Capture / Post Prod: OBS / Camtasia

Пікірлер: 15

@TheEmbeddedHobbyist 11 ай бұрын

Sorry but I've just got to say how much I love the fact that you use the bus's and not just have a drawing of every chip with net names on every pin. Then you have to guess where they all go a right bugger to find you have missed a link out.

@DigicoolThings 11 ай бұрын

Don’t say Sorry. I’m pretty sure it was your earlier comments that prompted me to revisit and use some bus connectors. I also totally agree with you. I always used bus connectors in the past, but a few recent schematics had suffered from the desire to get on with breadboarding the circuit “laziness”. 🤓

@TheEmbeddedHobbyist 11 ай бұрын

@@DigicoolThings we used to have the wire connection show the direction the signal would be going in. in the early days i would have drawn the circuit by hand on scraps of paper or most often in your engineering log book and this was given to the drawing dept to produce the circuit diagram. None of this CAD systems on your desk.

@DigicoolThings 11 ай бұрын

@@TheEmbeddedHobbyist You are bringing back my memories now! I just checked on some of my old personal schematics, which carefully hand-drawn on paper, and my bus drawings also had direction signal arrows, as well as clearly labelled with what the bus was, and also diagonal lines through them showing the width / how many wires were on the bus. Perhaps the convenience of modern CAD software and the modern "urgency" of the world, has made us forget the effort and time it use to take us in designing and documenting each schematic. 🤔

@inerlogic 9 ай бұрын

*eating popcorn and yelling at the screen "THE DIP SWITCHES!!" Ugh.... why can't you hear me 2 months ago on the opposite side of the planet, lol ;)

@DigicoolThings 9 ай бұрын

LOL. Yeah, sometimes we miss the obvious. I suppose, trying to make a video also creates a bit of a distraction from my normal focus. 🙄

@7alken 11 ай бұрын

glad you are back :-) please, have you somewhere listed the exact aliexpress sources of all these cheap matching DIN connectors?

@DigicoolThings 11 ай бұрын

Thanks. I’ve had a few challenges this year, and I’m still waiting on flood repair insurance etc. But, I’m hopeful of getting fully back into my projects. Currently, I’m busy laying out my next PCB design, so hopefully my next video won’t be too far away. For the DIN connectors I'm using, search AliExpress for “rtlecs din 41612” (without the quotes). The connectors I’m using are the 364 type. i.e. 3 row, but 64 pins instead of 96 (A & C rows populated). I'm happy with the quality.

@7alken 11 ай бұрын

@@DigicoolThings thanks and good luck with everything!

@JohnScherer 11 ай бұрын

Hey, love this project, and love the bus connectors! One thought on your usb-c port on the backplane.. I think your method of pulling power from the USB-C port could be problematic. Without monitoing of the CC1/CC2 pins, it was my understanding that you would be limited by the supply to 500ma. The reason for this is, as connected, your backplane looks like a USB sink device, if a device has no ability to be able to follow the USB2 rules, the Type-C spec waives those rules and permits 500 mA.. max. I suppose if one was using a "dumb" 5v usb type-c supply, this might still work, but for many usb supplys, it likely won't. It would be better to use a usb type-c PD Trigger module. These have a small processor that talks to the psu. most of these boards allow you to choose the desired output voltage and vary in current rating from 3-5A at 5v. Go to ebay and search for "usb-c PD Type-c DC Fixed Voltage Power Trigger Module". It would be a nice addition to the backplane: www.ebay.com/itm/114517531316

@DigicoolThings 11 ай бұрын

Hi John. Thanks for the comment. I do understand what you are saying with regard to the use of USB-C for power. I imagine what you’ve described would indeed cause issues, if using a USB-C PD compliant power supply. I’m making use of the now commonly available, and relatively cheap, Raspberry Pi USB-C 5V 15W power adapters. My understanding is that these are simply a dumb 5V 3A Power Adapter which happens to use the USB-C connector (please let me know if I’ve got this wrong?). So, I’ve simply just used a plain USB-C female connector module, to allow the use of these power supplies as an alternative to the DC jack option. Fortunately, it appears the PD trigger module you’ve suggested can likely just be used in-place of the simple connector module I’ve used. i.e. Without any change needed to the BackPlane PCB. So, certainly very good advice if using a proper PD compliant USB-C Adapter! Thanks for pointing this out!

@JohnScherer 11 ай бұрын

@@DigicoolThings well good.. I share you dislike for the connectors, like those used for the RC2014 bus and derivates. I suppose the price of using the proper bus connector could turn some off, but I've got a large stash of these DIN style bus connectors so I'm excited for this.

@elirosenberg6603 11 ай бұрын

Glad to see the MECB project updated! Do you think you could make more available on your public github sometime soon? I am experimenting with MECB cards, but all I see thus far is the one Kicad template. Perhaps other repositories are still private. Thanks!

@DigicoolThings 11 ай бұрын

Thanks. It’s great to hear someone else is experimenting with MECB cards. I had just published the MECB template so far, to help others on a similar journey, and had planned to publish more once I had my first complete system. But, given it’s an ongoing journey, it would probably be useful for me to make more of my individual Card designs available, as I complete them. Leave it with me and I’ll take a look at adding some more GitHub content. Would also be awesome to hear a bit more about what you’re working on.

@DigicoolThings 11 ай бұрын

UPDATE: I've now added to the MECB GitHub repository, the PCB Gerbers and PDF viewable Schematics for the currently completed MECB Cards. i.e. The MECB_Backplane, MECB_Prototype, and MECB_TMS992xA_VDP Cards. Also, all, including the MECB_Template, have been updated to KiCAD v7.