I have been planning this in my head for the last couple of weeks… I am not sure if it’s even worthwhile as an idea but it’s a learning excercise for both PCB and a bit of coding…
The plan is a configurable unit comprising of a Brain and up to 4 STEP units
This PCB is the step unit. I have still to do the routing and I need to find some space to fit some standoffs as I will be using cheaper pots than ALPHAS down to cost.
It’s based arround a standard 8-step sequencer. project.
The functionality will hopefully include.
Per Module
- 8 Settings for CV to ( for VCO )
- 8 Settings for CV to ( for VCA )
- 8 Settings for the length of the note ( may or may not be that usefull)
- I2C bus for LCD…
Up to 4 modules will be able to connect to the brain.
The unit will
Be configureable for 1/32 2/16 4/8 sequences
have an internal Clock
have input for external clock.
have a side expansion module for any other function.
It’s more of a self learning experince more than anything else.
Cheers
Rob
8 Likes
1st issue… the control module is built to fit 3U ( 75mm ) panel… a standard LCD Module 16x2 D is 80mm wide.
I do have some super cool 128x32 OLED displays which are tiny. But they are fixed address.
Found these ERM8203-3 Displays with I2C board that looks to have A0-A2 Address pads on it.
Also just realised I am going to have to make some revisions for the output when in (1/32,2x16) mode… Will have to think on that. probably just feed everythig back to the mainbaord…
You may notice a SNAP line, no idea if it will work. It’s just a bunch of circles on the edge cuts… It’s one of the things I leaned from the clock build in terms of the jacks sub board…
Rob
3 Likes
What are you going to display on the screen? Could you get away with some 7 segs?
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Not 100% sure what is going on the displays… Maybee a replication of the LED’s showing the step across the whole unit from 1-32. Probably the sequencer number when it’s not in full 32 step mode. The fact the are “8” characters wide is telling me something…
I did breifely think of 7 Segment, but that would take up 28 extra tracks and data lines unless i had them addressed by a controller. I will go and look ad I2C interfaces anyway as it would be good to get that as an option for other projects.
The original plan was to combine the brain and 1st control moduel in one PCB. I may re-visit that although it makes revisions more tricky…
Cheers
Rob
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Seems if you want 4 7’s your covered
But not singular, but there is a chip the PCA95X1 that will do the job. https://www.nxp.com/docs/en/application-note/AN264.pdf
Not realy worth doing in terms of complexity and part count for a single display unless your short on digital control lines…
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Forgot to mention… The brains will be an Arduino Mega…
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Looks pretty cool! But will this be a 32 step sequencer or will it be 8 step and 4 note polyphonic? Can you configure that with the brain?
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the idea is that you can set it
32
16x2
8x4
the design is evolving all the time.
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Ok, so I spent ages last week working on a board footprint for an AS6408 multiplexer. I was going to use it as the interface to the POTS that provide analog inputs. But went of and designed a foot print for the little MAKER analoug mux boards you can get on ebay for £2
And then created a dual 16CH mux board. In reality I don’t think I will use it on this current project and will actually just fit a pair of 74HC4067 in the design of the circuit. In fact I will probably do a REV2 of the controler boards and fit the Mux on them 74HC4051 so the multiplexing is done at source.
So although the plan changed rappidly through the day, the learning and ideas are worthwhile.
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had to pay a surcharge for putting in s snap line as it classes as two boards 
Rob
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Even in China, capitalism is capitalism
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I was told by a PHD candidate from Shenzou that I used to work with that it was actually “C.H.I.N.A” for “Communism Here In Name Alone.”
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next batch, i will just silk screen a cut line and get the hacksaw out…
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Could you score it with a hobby knife and break it over the edge of a piece of wood like other plastic or aluminum? Anybody here ever tried that? Just curious really…
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Not sure, but I think they surcharge if part of your circuit is not connected to the other part and it just looks like it’s meant to be two.
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BASTARDS! They would, wouldn’t they? Run a fake trace across grounds or something…
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How much was the surcharge?
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it was £3.56 for the 5… so just paid up…
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Looks like I was wrong:
https://jlcpcb.com//quote/pcbOrderFaq/Different%20Design%20in%20Panel
If you are just in the prototype phase and want to save money, you can place your different designs all inside one overall board outline and use lines drawn in the silk layer to mark out the separate the PCBs. Then, when you receive the PCB, carefully cut them apart yourself (we recommend you do this before you assemble the PCBs!).
Like the PCB shown below, the yellow lines are drawn in the silk layers showing how you can merge 3 different PCBs in one gerber without incurring any extra costs.
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Yeah, read that after the event…
Main problem is I log in with google, and I never check my gmail which is where the notification went to…
The board better bloomin snap, was a chore to create the line…
Thanks
Rob
