FantomXR

Another MIDIbox core

37 posts in this topic

Hey people,

since I'd like to be independent from the availability of the STM32F4-discovery board I started designing my own board, which has an STM32F407VGT6 on board. Its an LFQP 100 package, so not easy to solder. I have a reflow oven and the first PCB I made seems to work fine.

The PCB has very few components. This was just a quick test board to see if the basic circuit of the STM32F4 is working. It's basically just the STM itself and it's components like caps and crystal. Also there is a 3.3V regulator (based on 1117 but will change to TC2117) to power the uC. I added a pinheader for USB connection (on the very left), a pinheader for SWD to flash the bootloader and a reset-header. 

On the right you see the HCT541, which connects to J8/9 (tested: works fine). Also I added an MCP3208 and HC595 for an AINSER64-like-analog-scanning. 

On the bottom of the PCB there is a MicroSD-slot. 

No changes in the firmware are needed to use this. The only thing one need to do is flashing the bootloader the first time. @latigid on made a nice "how-to": http://wiki.midibox.org/doku.php?id=wcore After that you can use the MIOS as is.

So, why I'm telling you this? 

This core is already very specific for my applications. But if you are interested I could upload the minimal circuit for the STM32F4 to work and you could add all headers and components that YOU need by yourself. So in theory you could recreate the original MIDIbox core but you should end up with a much smaller footprint (especially regarding height). 

If you need assistance regarding soldering the STM32F4 I can offer to reflow-solder it for you. 


I'll clean up my circuit and upload it the next days!

 

Best,
Chris

Foto 05.02.18, 19 51 31.jpg

Foto 05.02.18, 19 46 00.jpg

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Is there a port available for a control surface? J10A or J10B?

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any news on this?... need to make a new user project (cc-rec). and want to save money and size. this here could be a option.

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What "news" do you mean? This core is up and running. :-) 

Of course it can be extended to fit your needs...

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hi. i am not clear how you want to handle this. do i or do you extend this. since i saw no files and you have the reflow oven - i assume you  keep it on your side - so say a whish and you adapt? i will  make a topic on user projects the next days... i have already a ui shematic which only needs a j8-9. i will also need 2x midi in and 1-2 midi outs. + the sdcard on the core. thats all. i invite you via pm to the topic once done. maybe we find a solution - would be nice. (the device will be a 4 part controlchange looper)

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Na.... I'm very busy at the moment. So I can't do it for you. But I could upload the eagle-schematic / board-file so you can adapt it by yourself. 

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yes please would be nice. can you recommend a pcb fabricator?

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9 minutes ago, Phatline said:

yes please would be nice. can you recommend a pcb fabricator?

You can download it here:
https://www.dropbox.com/s/9gkkxd1qafu9bfg/MinimalCore.zip?dl=0

I order my PCBs at elecrow. 
If you order there than you can do some improvements on the PCB like change all vias to a smaller diameter (0,32mm is minimum). Also the routing can be improved for sure. This was just quick and dirty to test the circuit. Meanwhile I used this design in other projects which are much more complicated than this. So I can confirm that the circuit works.

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12 hours ago, FantomXR said:

Na.... I'm very busy at the moment. So I can't do it for you. But I could upload the eagle-schematic / board-file so you can adapt it by yourself. 

Where j10 a j10b control surface ports?

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@tedysurwarnady, read the first post again, 

Quote

This core is already very specific for my applications.

He designed it for a very specific purpose, stay with the regular core for what you want to do

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@FantomXR I'd like to have a go at making one of these for testing, can you tell me the part number MicroSD-slot, these items have a lot of different mount types.

Thanks

George 

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Posted (edited)

I had some of these boards made and soldered one up and I'm happy to report it works. I have to finish populating the PCB, but all looks good, bootloader flashed and the small USB 2x2 app loaded, no problems so far. I have yet to located a suitable SD card holder for the PCB, I have a few coming in the mail though.

 

Edited by slo
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very cool! post the suiting sd card socket... and all other usefull expirience...

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Great to hear that it works! 

I’m not at my computer at the moment. I’m not sure what kind of SD connector I used in that layout. I can look it up tomorrow. 

Either it is one that is called TF01 and I bought a bunch of them from Seeed-Studio but as far as I know they are not available anymore. That’s why I changed the connector to a Molex-Connector which is available at Mouser. I’ll look it up for you. 

Anyway: since the pinout is straight forward it is very easy to replace the connector in the design! 

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By the way: I meanwhile have a pick and place machine and improved the design which I populated here. 

So if there is interest I could produce some of those boards .... 

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@FantomXR Thanks for info and the files....:)....it was a fun little build and I’m thinking of a number of small scale projects for it. Hooked up Midi I/O today, working well and tested USB host mode with a controller connected too.

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Posted (edited)

Great!!! 

How did you mount ge STM? This was a tough part....  now with my pick and place machine it’s easy. 

Edited by FantomXR

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hei.

is the rest of layout the same as the files you released here? (specially the j89 10 11... and the mounting holes?)

i ask because i would then project around this- to simple plug your core into my UI...

i would then if i get it fit - need some of those cores.

if you make a run how many is minimum. and what is priceing. do the place machine pick all smd parts on top?

 

mike.

 

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Posted (edited)

na i think i cant use - i need midi a and b. you have only one midi port when looking at your shematic and board?

it has 2 midiports yes!

Edited by Phatline

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Quote

How did you mount ge STM?

@FantomXRI made a stencil for a solder mask from the files you provided, then just hand placed components and then it went into a reflow oven

@Phatline With Midi I/O module connected you get 2 in and 2 out midi connections 

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Hi,
Finally?..
What is the features of this board?
Which legacy ports are available?
What is the size of the board?

For which purpose did you think it for?
Did you make some specific changes in the MIOS32? Did you adapt it  properly?
I'm opinion is that it should be fine to get the same features/ports/possibilities as the Core8 but with a core32...
Could we help you to improve it?

@FantomXR Your soldering of the stm seems clean, perfect on the picture...
I will be interested in an oven soldering, can you provide this service to people here? For prototyping or small series.

Best
Bruno

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Posted (edited)

The sense behind this layout is just a proof of concept. My goal was to have an alternative to the discovery board. This design shows the minimal circuit which is necessary to get the STM running.

This is why I left out almost all connectors from the original Core-Board. My goal was not to recreate a replacement because for my usecases the original board has tons of features I don’t need. 

With that said: you are invited to take the layout and adapt it to your needs. To be honest most of the connectors should be straight forward pin-to-pin routing from the STM. 

Edited by FantomXR

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@Antichambre I could provide such service. The most time consuming thing is to set up the pick and place machine with the necessary parts. So prototyping (= only one PCB) will be a a lot of work. But for small series I would be open. 

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