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A neat way to couple WS2812B programmable LEDs (pLEDs) with a silicone button pad (e.g. Sparkfun)
Power input is +5V via a 3-pin 100mil connector (or Molex) and a Schottky diode. The value of electrolytic capacitor C1 is not critical.
The pLED chain enters via J2:pin 6 and resistor R1. The resistor should be replaced with a wire link for each additional module (i.e. only the first in the chain gets a resistor, the remainder stuffed with wire links). The serial chain then follows a snake pattern to J3, where additional pLED modules may be connected. The RC (R2, C18) end termination shouldn't be necessary, but can be trialled should problems with signal reflection arise.
Switches are connected in a 4*4 matrix with the given mapping. D0 refers to pin 10 of the IDC header (i.e. top right) for both DIN and DOUT.
Type | Qty | Value | Package | Parts | Notes |
---|---|---|---|---|---|
resistors | |||||
20 | 49k9 | 0204/7 | R1, R2, R4, R5, R6, R7, R8, R10, R11, R12, R13, R14, R16, R17, R18, R19, R20, R22, R23, R24 | ||
4 | 30k | 0204/7 | R3, R9, R15, R21 | nominal gain can be adjusted e.g. (22k/49.9k)*5V = 2.2V | |
capacitors | |||||
4 | 10p | 025×050 | C1, C3, C5, C7 | ||
9 | 100n | 025×050 | C10, C12, C13, C14, C15, C16, C17, C18, C20 | remove 1 if powering from Core | |
3 | 10u | electrolytic 2,5-6 | C9, C11, C19 | remove 1 if powering from Core | |
4 | optional | 025×050 | C2, C4, C6, C8 | can use another e.g. 10pF cap here for more filtering | |
inductors | |||||
2 | BEAD | 5MM | L1, L2 | ||
ICs | |||||
2 | MCP6002P | DIL08 | IC2, IC4 | sockets are recommended | |
2 | TL072P | DIL08 | IC1, IC3 | sockets are recommended | |
Vreg | |||||
1 | optional | TO-220 | VR1 | remove if powering from Core | |
headers | |||||
7 | 1X02_SMALL | JP1, JP2, JP3, JP4, JP5, JP6, JP7 | check board for headers as SIL strips of 3, 5 or 6 | ||
8 | 1X03_SMALL | JP8, JP9, JP10, JP11, JP12, JP13, JP14, JP15 | |||
2 | 2*5 (shrouded) | J1, J2 |
v1.2: first release.
Putting the board together is simple. As usual, start with the flattest components and work your way up.
For connection to a Control Board, use pin headers placed on the opposite side as the rest of the components i.e. follow the silkscreen markings. For standalone use, you probably want header pins (or sockets, or even bare wires if you wish) on the same side as the remaining circuitry.
For simplest results, use the complementary Control Board. Otherwise see below for header functions.
J1 carries the scaled CV to J5A or J5B of an STM32F4 Core module.
Currently the design is © 2016 antilog devices with all rights reserved; all documentation is CC BY-NC-SA 3.0.