Thursday, January 24, 2019

12 Gate 16 CV USB MIDI Interface: BOM, Build Guide, Schematic, PCB and Code

Overview
This is a USB-powered, Teensy-based interface that has 16 CV outputs and 12 gate outputs. USB MIDI channels 1 - 8 are mapped to CV outputs 1 - 16 for pitch and velocity, and gates 1 - 8 for note on and off events. Gates 9 - 12 are mapped to note on and off events only on channel 9, and also will send a sync and transport signal based on MIDI clock messages if received. CV is 12 bit from 0V to 4V, gates 1 - 8 are 0 and 5V, and gates 9 - 12 are 0 and 3.3v.




Schematic 



PCB
See: https://github.com/little-scale/eurorack/tree/master/USB_MIDI_12_gate_16_cv_interface


Code 
See: https://github.com/little-scale/eurorack/tree/master/USB_MIDI_12_gate_16_cv_interface


Bill of Materials
1 x 12 Gate 16 CV USB MIDI Interface PCB
1 x Teensy LC or 3.2 and associated header pins
40 x 1k 1% resistors
8 x MCP4822 through hole DAC and 8 8-pin IC sockets
1 x 74HC595 through hole shift register and 1 16-pin IC socket
8 x red 3mm LEDs
4 x green 3mm LEDs
28 x PJ301M-12 3.5 mm sockets



Build Guide
 This is the PCB.


 Place and solder the 40 x 1k resistors.


Place and solder the 8 x red 3mm LEDs. In the picture, the short negative leg is oriented towards the lower edge of the picture.


Place and solder the 4 x green 3mm LEDs. In the picture, the short negative leg is oriented towards the lower edge of the picture.


Place and solder the 8 x 8-pin IC sockets. In the picture, the indent is oriented towards the upper edge of the picture.


Place and solder the 1 x 16-pin IC socket. In the picture, the indent is oriented towards the upper edge of the picture.


If the Teensy does not have headers, place and solder two rows of headers.


Place and solder the Teensy. In the picture, the USB port is oriented towards the left edge of the photo.


 Place and solder 28 x PJ301M-12


Populate the IC sockets, paying attention to the orientation of the MCP3822 DACs and the shift register 74hc595.






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