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MIDI Bass Pedal Encoder

 

MIDI BASS PEDAL UNIT

Nowadays MIDI devices come in all shapes and forms and MIDI controllers range from standard keyboards to various trigger devices. While most MIDI triggers are controlled by hand some people like to use their feet also, allowing a guitarist or keyboard player to add bass or trigger drums or other MIDI sources, while simultaneously playing their instrument by hand. A number of MIDI bass pedals have appeared on the market in the last few years but their price is in the hundreds of pounds range. So I decided to design and build my own bass pedal unit.

 

The MIDI Bass Pedal circuit is capable of encoding any number of momentary action, push to make, single pole single throw (SPST), switches from 1 up to 64 to produce the equivalent MIDI note-on/note-off data commands. The encoded switches are wired via IN4148 diodes. The keys are arranged in an 8 x 8 (64 keys) matrix.

 

The Programme Switch allows the unit to be set to any MIDI start Note and any MIDI channel (1 to 16). The encoded switches are wired via IN4148 diodes, see switches schematic. Also there is a wiring diagram available

 

This unit can be connected to new bass pedals or it can be used with an older non-MIDI bass pedals by using magnetic/reed switches to isolate the old and new scanning circuits. This will allow the older bass pedal synthesizer to continue to operate as normal while also providing a MIDI output.

 

 

 

PCB_N0_DIP.jpg (122586 bytes)

 

MIDI BASS PEDAL ENCODER

ITEM#: MIDIBASSPED

PRICE:  €35.00

 
 

 

 

 

The MIDI Bass Pedal Encoder Unit consists of:

 

  • The MIDI channel (1-16) is user programmable 
  • The velocity byte is preset to the maximum value.
  • The start Note of the keyboard encoder is user programmable, ranging from MIDI note 0 (C-1) to MIDI note 63 (D#4),
  • A wiring diagram is available.
  • A Miduino kit including a suitable pre-programmed Atmega168,
  • A 2.1mm power socket, and associated LED, ,
  • A MIDI 5-pin DIN output socket,
  • The circuit schematic is available,
  • The switches schematic is available

 

 

The  MIDI Bass Pedal Encoder unit requires:

  • a 9v battery or equivalent DC power source
  • Suitable key-switches or magnetic reed switches and associated IN4148 diodes

 

Circuit Schematic:

A circuit schematic of the MIDI Bass Pedal Encoder shows the switch connections. Note that for this project the 4-way DIL switch is not required. 

     

Assembly:

The kit includes all parts necessary, the assembly is straightforward and well documented. This design does not include a USB chip, it is designed to use a FTDI USB 232-TTL cable to program the microcontroller.  However since the cable plugs directly into the Miduino, you can use one cable for multiple Miduinos.

   

MIDI Wiring:

The MIDI IN and OUT connections use 5-Pin 180 degree DIN sockets. Note that the MIDI IN/OUT wiring is polarised and the correct pins should be used. 

 

Programme Mode:

At power-up, when switching on the unit, if the programme switch is pressed and held on, then the unit will enter programme mode, and the programme LED is lit. 

 

Now the first  Note-on command from a MIDI keyboard or sequencer is detected and stored in the EEPROM. This note is the first of 64 consecutive note values. Also the MIDI channel, which the Note-On command is transmitted on, is also stored in the EEPROM. The 64 notes (0 to 63) are added sequentially after whatever start note (choice of 0 to 64) you select. So if you select 36 as your start note the last note is 36+63 = 99.

 

After the Note-on is detected the unit goes into normal operating mode, and the programme LED is off. So the 64 notes are programmed to operate consecutively from only the first Note-on command detected. 

 

Programming the unit only has to be done once and the MIDI start-note and channel are stored internally in the EEPROM and the unit will continue to operate in this mode, (even when power is removed and re-applied), until the unit is re-programmed. 

 

 

MIDI Bass Pedal Wiring:

The switches are organized in a 8 x 8 matrix (64 switches) arrangement. The switch keys are wired as shown in the  Wiring diagram.

 

Note that the red dotted lines implies the extra switches and diodes. For example, at the top, switches and diodes 0, 6 and 7 are shown but the circuit is also wired in a loop to switches and diodes 1 2,3,4 and 5. Also the other sides of these switches/diodes are connected down to Miduino contacts D2 to D9.


The lowest note  is switch 0 wired via D0 between Pins D2 and D10.
D2 is also wired to the Anode of D8 and via SW8 to D11. 
D2 is also wired to the Anode of D16 and via SW16 to D12.
D2 is also wired to the Anode of D24 and via SW24 to D14.
D2 is also wired to the Anode of D32 and via SW32 to D15.
D2 is also wired to the Anode of D40 and via SW40 to D16.
D2 is also wired to the Anode of D48 and via SW48 to D17.
D2 is also wired to the Anode of D56 and via SW56 to D18.

 

So, for example, terminal connected to D10  is wired to one side of the 8 key switches SW 0 to SW7 and the wire can be looped from one key switch to the next.

 

Each of the other side of these switches SW0 to SW7 is wired to a diode on the Cathode (K) side (end of diode with stripe).

The other side of each of these diodes is looped to 7 other diodes. For example Anode (A) of diode DO is looped to D8 then to D16 then to D24 etc. down to D56 and finally to digital terminal D2 on the Miduino.

 

The rest of the wiring is done in a similar manner.

 

Below is an example of a finished Bass Pedal Unit. NOTE I am selling the MIDI electronic kit only and NOT the Pedals.

 

 

 

 

 
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