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Differences between MBHP_CORE_V3 and MBHP_CORE_V2

This page contains some old docs which are only required if you are going to populate the an old version of the core module. The most current version is documented here.
The main differences:

  • the programming port J3 has been removed, since in-circuit-programming is now realized via the MIDI interface
  • J6/J7 and J8/J9 have been combined to 2*5 pin DIL sockets
  • the crystal is now mounted at the top of the board
  • the 1k pull-up resistor R12 has been added to the J4:RC port - this enhancement is required if you are planning to use a MBHP_IIC_* module like MBHP_IIC_MIDI.
  • two bypass caps C7 and C8 have been added to improve the power integrity.


PCB data, can be viewed, modified and converted with Eagle Light. The .pdf based schematic has been created with xcircuit. There are no special eagle schematics available, since components have been netlisted in the .brd file directly!
Module Schematic Layout Data Quick-view
MBHP_CORE_V2 mbhp_core_v2.pdf mbhp_core_v2.brd mbhp_core_v2.gif

Soldering Guide

Start with soldering the 5 bridges which save you from creating a 2-layer board. You can use the cutted legs of caps and resistors, before you throw them away after you finished all the modules! :-)
The crystal has to be soldered on the bottom side. Take care that the metal case doesn't get in touch with tracks; isolation can be ensured by using an adhesive tape (sticky tape, "tesa film") underneath the crystal (not shown here).
Mount the parts. This picture shows two types of sockets: 1-row and 2-row SIL headers (for example J3, J4, J15...) and special connectors (J1, J2, J5, J12, J13...) which are available at Reichelt (called printplugs (="printstecker" in german). But don't get confused, SIL headers can be used for every port.
Don't forget the 6th bridge, which has to be soldered between the SC pin of J4 and Pin #28 of the PIC (was Pin #22 in earlier MIOS releases and PIC16F based projects). An isolated cable is recommended!
Add also the two additional Bypass Caps on the bottom side of the PCB as close to the power inputs of the PIC as possible. They improve the power integrity.
Note that the module will not work without 5 jumpers on the programming interface J3.
Apply power to the module after all parts except the PIC and the optocoupler are mounted. Check the voltage levels between the most important pins with a multimeter (analog or digital doesn't matter) before plugging the PIC and the 6N138 into the socket:
IC1:MCLR(1) - IC1:Vss(12) = 5V
IC1:Vdd(11) - IC1:Vss(12) = 5V
IC1:Vdd(32) - IC1:Vss(31) = 5V
IC2(8) - IC2:(5) = 5V
A picture of a finished board - just for nostalgic reasons ;-)
This was the official layout between 2002 and 2006

Last update: 2024-05-08

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