SPI-POTX2

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Tindie-mediums.png

SPI-POTX2-720px.jpg

Features

  • Dual Digital potentiometer
    • MCP4231 Dual Digital Pot
    • 7-bit: 128 Resistors (129 Steps)
    • Zero Scale to Full Scale Wiper operation
    • 10K
      • Other resistances optional: 5K, 50K, 100K
    • Power on reset to half wiper value
    • SPI Interface
      • SPI Serial Interface (10 MHz, modes 0,0 & 1,1)
      • High-Speed Read/Writes to wiper register
      • 10 MHz (max SPI speed)
  • 2.7V to 5.5V
  • Daisy-chain SPI connector
    • Slave Select (SS) should be star connected
  • 49x49mm form factor
  • (4) #4-40 mounting holes

Connectors

J1, J3 - SPI connector

  1. MISO
  2. +V
  3. SCK
  4. MOSI
  5. SS
  6. GND

J2 - SPI Connector

  • Matches Arduino SPI connector pinout
  1. MISO
  2. +V
  3. SCK
  4. MOSI
  5. SS
  6. GND

POT0, POT1

  1. GND
  2. B SIDE
  3. WIPER
  4. A SIDE
  5. +V

Driver Software

Factory Test Procedure

  • Test SPI-POTX2 card on RPI_PSOC5 Test Station

Hardware Setup

SPI-POTX2 P1889 720px.jpg

  • RPI_PSOC5
    • Raspberry Pi CPU Clone
  • RPI_SPI8
    • 8-channel SPI multiplexer
  • Unit Under Test (UUT)

SPI Cable

RPI_SPI8 (Marking) RPI_SPI8 Pin SPI-POTX2 Pin SPI-POTX2 Marking
Chip En (CE) 1 5 SS
MOSI (MO) 2 4 MOSI
MISO (MI) 3 1 MISO
SPICK (CK) 4 3 SCK
Vcc (+V) 5 2 +V
GND 6 6 GND

Run Tests

  • Run puTTY
    • Find COM Port in Device Manager
    • 115,200 baud
    • RTS/CTS flow control

RPI SPI8-puTTY setup.PNG

  • Hit ENTER to see menu
Land Boards, LLC - RPi Card Test Station
1 - Select RPP-UIO-16 Card
2 - Select RPPSOC Card
3 - Select RASPI-PLUS-GVS-CFG Card
4 - Select RASPI-GVS Card
5 - Select RASPI-PLUS-GVS Card
6 - Select RPI-I2C-HUB Card
7 - Select RPI-SPI8 Card
8 - Select SPI-POTX2 Card (via RPI-SPI8)
R - Read EEPROM
W - Write EEPROM
B - Bounce LED across Card GPIOs
T - Test Card
D - Debug Card
? - Print this menu
  • Select SPI-POTX2 Card by entering 8[ENTER]
8
Selected SPI-POTX2 card (vis RPI-SPI8)

Create Sawtooth Output

  • Enter T[ENTER] - Create ramped output
Testing SPI-POTX2 card (via RPI-SPI8), please wait
test_SPI_POTX2() - Reached function
test_SPI_POTX2() - Start SPI
test_SPI_POTX2() - Started SPI
  • Use scope to observe ramped output on POT0
    • CH 1 Yellow = SPI_CE0
    • CH 2 CYAN = POT0 wiper

SPI-POTX2-14.png

Test Software

Assembly Sheet