StrichLux/IO-SPI

The StrichLux IO-SPI module will provide one universe of SPI output for the StrichLux system, mainly for use driving addressable LED strips. Initially it will only support output, but the hardware supports output, so it could be implemented later.

Project Status

• 2012-06-06: Modularized the SPI transceiver code and got it all working this way. Should be relatively simple to add the interface code to get data from the framebuffer now.
• 2012-06-03: More troubleshooting, got the code working and it controls the LEDs! Flaky hardware-wise though because the level shifter can only sink 10uA, and the strips want 50uA to reliably drive. Need to order another level shifter without the automatic direction feature and test it.
• 2012-06-02: Lots of troubleshooting, not quite there yet. Was hanging after one cycle, which is now fixed/working in the simulator. Need to re-test against real hardware next time I'm at the lab.
• 2012-06-01: Assembled and started testing.
• 2012-05-31: Boards are here!
• 2012-05-24: Parts ordered and received. Still waiting for boards.
• 2012-04-29: Finished schematic, done board layout, checklists run, sent to Laen for manufacturing. Parts still need to be ordered.
• 2012-04-28: Started schematicizing and BOM selection.
• 2012-04-24: Started initial planning.

Specs

• Based around the Lattice MachXO2-256 CPLD (common to other IO modules)
• Will pass power through from one of the high power busses
  • Needs to handle 50W! (4.25A @ 12V or 10A @ 5V)
• JST SM seems to be a common connector for these
  • But it's wire-to-wire only, no PCB mount version available
  • Using a 2x3 Mini-Fit Jr. connector instead, 6 pins so it can carry a full SPI bus (MISO/MOSI/!SS/SCLK) plus power

Rev. 1 Issues

• Missing silkscreen on U1
• TDO/TDI connect to the wrong pins
• SN needs to be tied high

Architecture

<graph>graph {output: svg;}[ SPI Hardened Core ] <-- Wishbone --> [ Module Controller Softcore ]</graph>