Suggestion for buffering J9 (DIN pins)

MIDIbox SEQ
1

I have Illmenator’s 16x4 BLM up and running and now am looking at adding it as a peripheral to my SEQV4 but I have run into a problem, the length of the leads I need for it to work is VERY short and the way I was planning on deploying it was to use a Mini DIN8 connector and cable.  I can get it to work fine with a short length of ribbon cable but when I use a similar length DIN cable, the DOUT stuff works fine, but the buttons do not work reliably.  I have the shield of the cable connected to ground.

 

Would a viable solution to fix this be to buffer the serial output from the BLM? Would this work the same way as buffering a midi signal (hex inverter)?  Any input would be appreciated..

2

You could use the same 74HCT541 based buffer circuit like known from the MBHP_CORE_LPC17 module: http://www.ucapps.de/mbhp/mbhp_core_lpc17.pdf

 

Btw.: this chip would also allow you to buffer J19 for your AOUT module properly.

 

Best Regards, Thorsten.

3

perfect, already have some from the level shifter. so my premise is correct then, buffering the din should get me more length? That was the chip in the breakout box you had a pic of correct?

4

Can I get a quick opinion of this quick and easy board and schem?

 

 

 

 

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5

“BLM J9 SI” doesn’t need to be buffered, remove this line.

J8 and J9 RC and SC are both output pins, it seems that you handled one RC and one SC line as inputs instead - change this connection.

 

I would propose to have a look into the MBHP_CORE_LPC17 schematic again, it’s a very simple circuit!

 

Best Regards, Thorsten.

6

Thanks, that helps a lot.  Have not even looked at the LPC schem (still on the STM core),  Will revise

 

Just so i have this clear in my head, SI is the input back to the core for the DIN, correct? This is my problem, the DOUT functionality works fine, the DIN stuff does not though so I figured that pin would need buffering

7

SI is an uncritical signal, because it goes from a single 74HC165 output to a single input of the core, and it’s already at 5V…

 

SC and RC are the critical outputs from the core, because they go to multiple 74HC595 and 74HC165 pins

 

Best Regards, Thorsten.

8

Ok, 

 

This should be correct now:  

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9

success! I’ll branch this thread with all the case and design files  :smile:.  Now its time so see how long I can go

 

 

I suppose I should patch in J19 for a complete solution..

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