FantomXR

Another MIDIbox core

13 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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