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fade - A fancier attempt at a dedicated volume control
Work in progress
This is a generalized development board for V-USB, using the ATTiny85 without a crystal.
The board files are free for re-use, modification, and manufacture without restriction.
The repository here contains KiCAD sources (schematic/board files), basic V-USB code that implements a key-based HID media controller (with modifications for this board) and a Bill of Materials listing.
Note: The VID/PID need to be properly defined before using this board in production. This should be your own VID/PID, or from a source such as http://pid.codes.
Usable pins
| Pin on ATTiny | Goes to | Connected to ISP as |
|---|---|---|
| PB0 | Pin 2 on connector | MOSI |
| PB3 | Pin 3 on connector | Not Connected |
| PB4 | Pin 4 on connector | Not Connected |
Bill of Materials
This builds one board
| Quantity | Placement | Description | Digikey Part Number | Notes |
|---|---|---|---|---|
| 1 | Center, with corner dot aligned to silkscreened dot | ATTiny85 (PDIP) | ATTINY85-20PU-ND | ATTiny in PDIP format |
| 1 | 2.2K | 2.2K ohm resistor | 1276-5070-1-ND | Pull-up resistor for D- (0603 imperial) |
| 1 | 4.7K | 4.7k ohm resistor | P4.7KGCT-ND | Pull-up resistor for AVR RESET line (0603 imperial) |
| 1 | C1 | 10uF 16V 20% X6S capacitor | 490-10499-1-ND | Bypass at USB input (0805 imperial) |
| 1 | C2 | 0.1uF capacitor | 490-1532-1-ND | Just buy a bunch. Singles are expensive! (0603 imperial) |
| 1 | USB box at board edge (4 pads with plated through-holes) | USB connector | WM17116CT-ND | Mini USB-B |
| 2 | 68R | 68 ohm resistor | 311-68GRCT-ND | USB data terminators (0603 imperial) |
| 2 | D1+D2 with striped side opposite board markings | 3.6V Zener diode | BZT52C3V6-E3-08-ND | SOD123 format |
Optional components
| Quantity | Placement | Description | Digikey Part Number | Notes |
|---|---|---|---|---|
| 1 | ATTiny footprint (aligned with the U silk) | 8 pin DIP socket | A120347-ND | The older socket used in prototypes was P/N 390261-2 and was discontinued |
| 1 | 330R | 330 ohm resistor | 1276-5050-1-ND | Current limiting resistor for PWR LED |
| 1 | Next to 330R (+ - silk) | Power LED | 475-2512-1-ND | Red LED 0603 imperial |
| 1 | +5V / GND silk-screened box | Right angle 1x5 female header | S5480-ND | For connecting to carrier boards (female header) |
| 1 | +5V / GND silkscreened box | Right angle 1x5 male header | S1121E-05-ND | For connecting to carrier boards (male header) |
| 1 | 2x3 header | 6 pin AVR ISP header | 3M9459-ND | For flashing the ATTiny85 |
Flashing firmware
Ensure that you have all the avr tools necessary to compile the firmware. On Debian/Ubuntu based systems the dependencies are:
sudo apt-get install -y build-essential gcc-avr gdb-avr binutils-avr avr-libc avrdude
In the firmware directory (depending on how your system permissions are setup pre-pending sudo may be necessary):
cd firmware
make hex
make program
make fuse
Fuses (important)
These must be programmed, otherwise your board will not enumerate with the host.
avrdude -c buspirate -p attiny85 -P /dev/ttyUSB0
-U hfuse:w:0xdd:m -U lfuse:w:0xe1:m
Schematic
License
Board files, schematic and PCB are CC0 1.0 Universal.
V-USB firmware and accompanying source code is GPL 2.0 licensed.
For more information and full license text, see the LICENSE.md file in this repository.