Fadecandy Test Jig
This is a simple one-off test fixture that's designed to facilitate in-circuit debugging of the Fadecandy firmware, and doing reliable low-volume production.
My prototype consists of:
- An ugly hand-wired perfboard
- 0.1"-spaced pogo pins which connect to the Fadecandy board's "hacker port" as well as its output header
- A standard ARM JTAG header for firmware development using an external JTAG adapter
- A 2-LED string of WS2811 LEDs, for verifying the timing of the Fadecandy outputs
- A Teensy 3.0 board which coordinates production and testing tasks
The board is intended for two separate use cases:
- During firmware development, it's a simple breakout board for the JTAG port
- During low-volume production, the Teensy installs firmware and performs electrical testing
This board is a work-in-progress. This directory contains Teensyduino sketches which run on the onboard Teensy. More information about the hardware will be included later.
Hardware tidbits
- JTAG port uses 10K pull-up resistors to Fadecandy's 3.3v rail on all signals.
- Pogo pins are 2x Digi-Key part ED8178-16-ND
- Big green button next to pogo-pins to initiate programming/test
Teensy 3.0 pin assignment
| Pin | Description |
|---|---|
| Gnd | Shared ground |
| Vin | +5V power for testjig itself |
| 0 | Teensy RX, Fadecandy TX |
| 1 | Teensy TX, Fadecandy RX |
| 2 | To ground via green button |
| 3 | Fadecandy TCLK (SWCLK) |
| 4 | Fadecandy TMS (SWDIO) |
Testjig Firmwares
-
production- Programs bootloader and initial firmware image
- Runs electrical tests
- Communicates with the DUT processor using Serial Wire Debug
-
serial_passthrough- Teensyduino sketch
- Appears as a USB serial port device
- Passes through access to the DUT serial port
- When the green button is held, acts as a loopback for the DUT serial port, as one way to enter FC-Boot.
Contact
Micah Elizabeth Scott <micah@scanlime.org>