Category Archives: Hardware

DE0 Digital I/O Wing Expansion REV0 Complete

Schematic

Design ended up having only 10 LVDS signals broken out as that required less unique parts. The connectors are expensive (1-282834-0) running ~$5.70 in singles. I will be looking into alternatives to see if I can get the cost down. I found some on AliExpress but I will need to order them and test them to see if they are any good.

Layout

I also included a 4 position auxiliary power connector to power up external circuits. No power safety though (fuses/TVS) so use at your own risk!

DE0 Digital I/O Wing Expansion

Schematic

Started work on a expansion board for the DE0 FPGA development board. Planning on having 4 8-bit bi-directional level shifters giving 32 I/O and breaking out 12 LVDS signals to screw terminals. Basically a simple digital acquisition add on. Using the expansion template I made for the DE0 a couple days ago.

LVDS will be buffered to protect the FPGA. Have not picked the buffer chip yet. The bi-directional level shifter is the SN74LVC8T245PWR by Ti. Handles 1.65V to 5.5V on both sides and has basic ESD protection. I am debating putting over voltage protection on the I/O of the level shifters. A 50ohm resistor in series with the I/O plus a 5.6V TVS Diode should do the trick and not add to much cost to the board.

Layout

GitHub Repository Link!

Prop Dev Stick REV4 Update

Layout

Some changes from REV 3 to REV 4.

  • Micro SD Card Slot changed. Old one was Molex MFG# 502570-0893. New part is 4UCON MFG# 15882.
  • Tact Switch changed to more low profile switch.
  • ADC switched from AD7999YRJZ-1500RL7 to MAX11613EUA+. Slower ADC but increase from 8bit to 12bit resolution.
  • Changed Voltage Regulator from TS2937CW33 to NCP1117LPST33T3G.
  • Added 10uF Electrolytic Cap to 3.3V rail.
  • Crystal changed to low profile ABMM-6.000MHZ-B2-T.
  • Added voltage divider to switch to USB power if external power falls near cutoff for regulator.

    Render of the PCB from OSHPark.

    Top stencil pattern. The through hole pads on the micro USB connector are going to be soldered with the “Paste In Hole” method. I have not tried this yet but if it works I will be able to cut out an entire operation during production of the boards.

  • Propeller Development Stick REDUX REV3

    Finished the next revision of the Propeller Development Stick REDUX. The power switching has been changed to fix the flakiness of the past revision. I switched the TPS2115 to a TPS2113. This seems to have fixed the weird power switching issues. The layout has change completely. SD card slot is on the top side of the board and the power circuity and ADC are on the bottom now.