i_n_c_u_r_pcb

i_n_c_u_r

this extension project now has its own repo with upto date info here

this is an optional custom extension board for r_e_c_u_r. it adds 1x DIN (serial) midi input, 4x knobs and 4x CV analog inputs.

disclaimer: this is a fun diy project, but dont forget there are other ways to getting serial and cv control over recur parameters. USB midi is supported without any extras. other diy and commercial products exist that convert cv to midi, and serial to USB. in my opinion a general solution for cv-to-usb-midi applied to recur is more useful than a specific board that only works with recur

diy wiring

the schematic for this circuit shows exactly how the components are connected. from this you could try creating the circuit on breadboard, stripboard or even etching it yourself. if you take this route you may need to solder some wires to the GPIO pins on the bottom of the raspberry pi as some pins are covered by the screen.

add pictures here

pcb fabrication

instead of buying a pcb from me another option is to get some fabricated yourself. you need to send some gerber files to a fab house and they will print the boards and send them to you. the pcb size is 100x100mm and the default options are fine. i often use jlcpcb because they are reliable, cheap and give you an option of colours. remember though that the cheapest Chinese fab houses are not always the most ethical or environmently friendly - if you can afford it consider supporting local companies. often pcbs can only be ordered in batches of 5 or 10. If you are getting boards printed please share any spares with the community, either locally or via the facebook group.

BOM

REFERENCE	QUANTITY	DESCRIPTION	PACKAGE	NOTE
R1, R2, R3, R4	4	1K Resistor	through-hole	-
R5	1	220 Resistor	through-hole	-
R6	1	100K Resistor	through-hole	-
R7	1	470 Resistor	through-hole	-
D1, D2, D3, D4, D5, D6, D7, D8	8	BAT85 Diode	through-hole	can replace with BAT46
D9	1	1N4148 Diode	through-hole	-
U1	1	MCP3008 IC	DIP-16	you can get these from mouser ,adafruit, even ali
U2	1	6N138 IC	DIP-8	-
RV1, RV2, RV3, RV4	4	10K_LINEAR_POT	ALPHA	tayda ones work although shaft may be too short
J1, J2, J3, J4	4	3.5MM_JACK	THONKICONN	from thonk or 50pc from modular addict
J5	1	MIDI_DIN_IN	SD-50BV	mouser
J6	1	1X1_PIN_HEADER	-	-
J7	1	RCA_JACK	RCJ-024	mouser or ali
J8	1	20X2_PIN_HEADER	tall long stacking header	adafruit ones from mouser like this - the tall is needed to clear the ethernet port

OPTIONAL :

• some long enough screws and spacers note:measure these to hold it together.
• if you want your ic's in sockets you should buy some DIP-8 /16 also now
• if you only want the analog_inputs and not interested in serial_midi, you already have usb midi etc, then you can omit R5, R6, R7, D9, U2 from the BOM - see circuit schematic for details

BUILD

start with the lowest to place components : resistors, diodes, ic's

next i would place the two headers since soldering from the top can be awkward with too many components - NOTE these need to be placed upside down! ,:

• J8 needs the pins facing up from top of pcb so the screen can go ontop and raspberry pi can go underneath
• J6 also needs to soldered from the top so a jumper from the pi board can be run to bottom of circuit

finally place the pots and jacks.

rca video-out

if you want RCA video out from the pi on this pcb a jumper needs to be run from J6 to the composite video out on the raspberry pi board. on pi0 this is a labelled pin, however on pi3 you will need to solder directly to the board. i used a header-cable, cut one side to be soldered. The pin on pi3 is marked as PP24.

need to add some images and links to this guide !

stl files for enclosures and europanels

in the incur folder of the main repo you will find some 3d files created and shared by users to print inclosures / eurorack panels for this extention pcb

• euro_panel details
• enclosure file