Difference between revisions of "SPI-POTX2"

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(Created page with "Features Dual Digital potentiometer - MCP4231 7-bit: 128 Resistors (129 Steps) Zero Scale to Full Scale Wiper operation 10K SPI Interface SPI Serial Interface (10 MHz, modes 0...")
 
 
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Features
+
[[File:tindie-mediums.png|link=https://www.tindie.com/products/6298/]]
−
Dual Digital potentiometer - MCP4231
 
−
7-bit: 128 Resistors (129 Steps)
 
−
Zero Scale to Full Scale Wiper operation
 
−
10K
 
−
SPI Interface
 
−
SPI Serial Interface (10 MHz, modes 0,0 & 1,1)
 
−
High-Speed Read/Writes to wiper register
 
−
2.7V to 5.5V
 
−
Daisy-chain connector
 
−
49x49mm form factor
 
−
(4) #4-40 mounting holes
 
−
Connectors
 
−
J1, J3 - SPI connector
 
  
−
MISO
+
[[File:SPI-POTX2-720px.jpg]]
−
+V
 
−
SCK
 
−
MOSI
 
−
SS
 
−
GND
 
−
J2 - SPI Connector
 
  
−
MISO
+
== Features ==
−
+V
 
−
SCK
 
−
MOSI
 
−
SS
 
−
GND
 
−
POT0, POT1
 
  
−
GND
+
* Dual Digital potentiometer
−
B SIDE
+
** [http://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf MCP4231 Dual Digital Pot]
−
WIPER
+
** 7-bit: 128 Resistors (129 Steps)
−
A SIDE
+
** Zero Scale to Full Scale Wiper operation
−
+V
+
** 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 ==
 +
 
 +
[[file:SPI-POTX2-BW.png]]
 +
 
 +
=== J1, J3 - SPI connector - Rev X1 ===
 +
 
 +
* Two separate 1x5 headers
 +
** Used for chaining to other cards
 +
 
 +
# MISO
 +
# +V
 +
# SCK
 +
# MOSI
 +
# SS
 +
# GND
 +
 
 +
=== J1, J3 - SPI connector - Rev 2 ===
 +
 
 +
* Single 2x6 right angle header
 +
** Used for chaining to other cards
 +
 
 +
# MISO
 +
# +V
 +
# SCK
 +
# MOSI
 +
# SS
 +
# GND
 +
 
 +
=== J2 - SPI Connector ===
 +
 
 +
* Matches Arduino SPI connector pinout
 +
 
 +
# MISO
 +
# +V
 +
# SCK
 +
# MOSI
 +
# SS
 +
# GND
 +
 
 +
=== POT0 ===
 +
 
 +
# GND
 +
# B SIDE
 +
# WIPER
 +
# A SIDE
 +
# +V
 +
 
 +
=== POT1 - Rev X1 ===
 +
 
 +
# GND
 +
# A SIDE
 +
# WIPER
 +
# B SIDE
 +
# +V
 +
 
 +
* Rev X1 board has POT1 A, B Sides reversed on Silkscreen
 +
** Impacts POT1 Vcc/GND jumpers
 +
 
 +
=== POT1 - Rev 2 ===
 +
 
 +
# GND
 +
# B SIDE
 +
# WIPER
 +
# A SIDE
 +
# +V
 +
 
 +
* Rev 2 board updated so POT1 matches POT0
 +
 
 +
== Driver Software ==
 +
 
 +
* Set channel number on GPIO_22 (A0), GPIO_27 (A1), GPIO_17 (A2)
 +
* Do SPI transfer as 2 of 8-bit or 1 of 16-bit transfer(s)
 +
 
 +
=== Arduino Driver / Example Code ===
 +
 
 +
* [https://github.com/land-boards/lb-Arduino-Code/tree/master/LBCards/SPIPOTX2 SPI-POT-X2 GitHub Arduino Example Code]
 +
** Creates triangle wave output on both outputs
 +
 
 +
=== Raspberry Pi Example Code ===
 +
 
 +
[[file:RPI_SPI8_P1897_720PX.jpg]]
 +
 
 +
* Test SPI-POTX2 Dual pot card on the Raspberry Pi using [[RPI_SPI8]] SPI mux card
 +
** Mux card is easy to include/exclude option in the code
 +
<pre>
 +
# Set the next line to False if directly connecting to Raspberry Pi SPI bus
 +
USING_RPI_SPI8_CARD = True
 +
</pre>
 +
* Makes triangle waves on the pot wiper pins
 +
* [https://github.com/land-boards/RasPi/blob/master/RPI-SPI8/MCP4231_SPI_Test.py MCP4231_SPI_Test.py] - Our GitHub repo
 +
** [https://github.com/land-boards/RasPi/tree/master/RPI-SPI8 Readme file]
 +
 
 +
==== Raspberry Pi Reference Docs ====
 +
 
 +
* [https://www.raspberrypi.org/documentation/hardware/raspberrypi/spi/README.md SPI on the Raspberry Pi]
 +
* [https://pypi.org/project/spidev/ Python Spidev]
 +
 
 +
== Factory Test Procedure ==
 +
 
 +
* Test SPI-POTX2 card on [[RPI_PSOC5]] Test Station
 +
 
 +
=== Hardware Setup ===
 +
 
 +
[[FILE:SPI-POTX2_P1889_720px.jpg]]
 +
 
 +
* [[RPI_PSOC5]]
 +
** Raspberry Pi CPU Clone
 +
* [[RPI_SPI8]]
 +
** 8-channel SPI multiplexer
 +
* Unit Under Test (UUT)
 +
 
 +
==== SPI Cable ====
 +
 
 +
{| class="wikitable"
 +
! 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
 +
 
 +
[[FILE:RPI_SPI8-puTTY_setup.PNG]]
 +
 
 +
* Hit ENTER to see menu
 +
<pre>
 +
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
 +
</pre>
 +
* Select SPI-POTX2 Card by entering 8[ENTER]
 +
<pre>
 +
8
 +
Selected SPI-POTX2 card (vis RPI-SPI8)
 +
</pre>
 +
 
 +
=== Create Sawtooth Output ===
 +
 
 +
* Enter T[ENTER] - Create ramped output
 +
<pre>
 +
Testing SPI-POTX2 card (via RPI-SPI8), please wait
 +
test_SPI_POTX2() - Reached function
 +
test_SPI_POTX2() - Start SPI
 +
test_SPI_POTX2() - Started SPI</pre>
 +
* Use scope to observe ramped output on POT0
 +
** CH 1 Yellow = SPI_CE0
 +
** CH 2 Cyan = POT0 wiper
 +
 
 +
[[file:SPI-POTX2-14.png]]
 +
 
 +
=== Test Software ===
 +
 
 +
* Runs on [[RPI_PSOC5]]
 +
* [https://github.com/land-boards/RasPi/tree/master/RPI_PSOC5/RPI_PSOC5_RPI_SPI8_CARD_TEST.cydsn GitHub repo]
 +
** [https://github.com/land-boards/RasPi/blob/master/RPI_PSOC5/RPI_PSOC5_CARD_TEST_STATION.cydsn/Test_RPI_SPI8.c Test_RPI_SPI8.c] - Bounce LED across [[LED-TEST-2]] card
 +
 
 +
* Runs on [[RPI_PSOC5]]
 +
* Uses [[RPI_SPI8]]
 +
* [https://github.com/land-boards/RasPi/tree/master/RPI_PSOC5/RPI_PSOC5_RPI_SPI8_CARD_TEST.cydsn GitHub repo]
 +
** [https://github.com/land-boards/RasPi/blob/master/RPI_PSOC5/RPI_PSOC5_RPI_SPI8_CARD_TEST.cydsn/Test_RPI_SPI8.c Test_RPI_SPI8.c] - Test with SPI-POTX2 card
 +
 
 +
== Changes ==
 +
 
 +
=== Rev 2 ===
 +
 
 +
* Swapped POT1 A, B pins to match POT0 and silkscreen
 +
* Combined SPI connectors from 2 to 1 of 2x6 connector
 +
* Added SPI pin names to reverse side silkscreen
 +
 
 +
[[file:SPI-POT_Rev2_FRONT__3D.png]]
 +
 
 +
=== Rev X1 ===
 +
 
 +
* POT1 A, B pins swapped on silkscreen
 +
** POT1 Vcc, GND taps can not be shunted directly - need jumper cables to correct
 +
 
 +
== Assembly Sheet ==
 +
 
 +
* [[SPI-POTX2 Rev 2 Assembly Sheet]]
 +
* [[SPI-POTX2 Assembly Sheet|SPI-POTX2 Rev X1 Assembly Sheet]]

Latest revision as of 15:27, 16 May 2022

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

SPI-POTX2-BW.png

J1, J3 - SPI connector - Rev X1

  • Two separate 1x5 headers
    • Used for chaining to other cards
  1. MISO
  2. +V
  3. SCK
  4. MOSI
  5. SS
  6. GND

J1, J3 - SPI connector - Rev 2

  • Single 2x6 right angle header
    • Used for chaining to other cards
  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

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

POT1 - Rev X1

  1. GND
  2. A SIDE
  3. WIPER
  4. B SIDE
  5. +V
  • Rev X1 board has POT1 A, B Sides reversed on Silkscreen
    • Impacts POT1 Vcc/GND jumpers

POT1 - Rev 2

  1. GND
  2. B SIDE
  3. WIPER
  4. A SIDE
  5. +V
  • Rev 2 board updated so POT1 matches POT0

Driver Software

  • Set channel number on GPIO_22 (A0), GPIO_27 (A1), GPIO_17 (A2)
  • Do SPI transfer as 2 of 8-bit or 1 of 16-bit transfer(s)

Arduino Driver / Example Code

Raspberry Pi Example Code

RPI SPI8 P1897 720PX.jpg

  • Test SPI-POTX2 Dual pot card on the Raspberry Pi using RPI_SPI8 SPI mux card
    • Mux card is easy to include/exclude option in the code
# Set the next line to False if directly connecting to Raspberry Pi SPI bus
USING_RPI_SPI8_CARD = True

Raspberry Pi Reference Docs

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

Changes

Rev 2

  • Swapped POT1 A, B pins to match POT0 and silkscreen
  • Combined SPI connectors from 2 to 1 of 2x6 connector
  • Added SPI pin names to reverse side silkscreen

SPI-POT Rev2 FRONT 3D.png

Rev X1

  • POT1 A, B pins swapped on silkscreen
    • POT1 Vcc, GND taps can not be shunted directly - need jumper cables to correct

Assembly Sheet

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