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====== MBHP_Genesis_LS ======

This is the schematic for the breakaway MBHP_Genesis_LS board included with the MBQG_FP front panel board. This should be sufficient for anyone to build a copy of this circuit on prototype board.
{{http://midibox.org/forums/uploads/monthly_2016_04/large.mbhp_genesis_ls.png.9b8e551b7d5d2244df873eeb7107f1e0.png}}

===== Explanation =====
When using the MBHP_Genesis module with a MCU supplied at less than 5V, especially when using several modules in parallel, a buffer circuit will be required between the MCU and the modules. This is a very simple circuit that consists of two 20-pin 74HCT series ICs and two power supply bypass capacitors, and can easily be built on prototyping board.

For buffering the data lines, a bidirectional buffer must be used; a common one is 74HCT245. Connect the eight lines from the MCU board to data pins B; connect the eight lines from the MBHP_Genesis board to data pins A; connect the /OE pin to the buffered /CS line (on the MBHP_Genesis side of the buffer); connect the DIR pin to the buffered /RD line (same thing); and connect a 0.1uF capacitor across the supply rails of the buffer chip.

For buffering the address lines, which are unidirectional from MCU to MBHP_Genesis, use a 74HCT541, with its two /OE pins always active (grounded). Alternatively you can use another 74HCT245, with /OE permanently active (grounded) and DIR set appropriately to always send the signals from the MCU to the MBHP_Genesis board. Again, bypass the supply rails with a capacitor.

Both buffers must be powered from +5V, not +3.3V or whatever the MCU uses. In addition, the MCU must be tolerant of 5V signals being applied to its I/O pins (the CORE_STM32F4 module is tolerant)--otherwise it will damage the MCU!

===== Parts List =====
^ Qty ^ Ref. Deg. ^ Part Name ^ Mouser Part Number ^ Description / Notes ^
| 1 | U101 | 74HCT245 | 595-SN74HCT245N | Bidirectional buffer chip |
| 1 | U102 | 74HCT541 | 595-SN74HCT541N | Buffer chip |
| 2 | [U101], [U102] | 20-pin 0.3" DIP socket | 571-1-2199298-6 | Socket for chips |
| 2 | J101, J102 | 10x2 pin header, 0.1" pitch | 649-68691-420HLF | Connectors to core and MBHP_Genesis module |
| 1 | J103 | 2x1 pin header, 0.1" pitch | 571-826936-2 | Connector for +5V power from core |
| 2 | C101, C102 | 0.1 uF | 21RZ310-RC | Power supply filtering capacitors for chips (place one next to each chip's +5V connection) |
| 1 | C103 | 10 uF | 140-REA100M1HBK0511P | Power supply filtering capacitor for board |
| 1 | --- | --- | e.g. 854-SB4 | Prototyping board to build circuit on |