Difference between revisions of "RPI-I2C-HUB"

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[[File:tindie-mediums.png|link=https://www.tindie.com/products/land_boards/i2c-multiplexer-for-the-raspberry-pi-rpi-i2c-hub/]]
 
[[File:tindie-mediums.png|link=https://www.tindie.com/products/land_boards/i2c-multiplexer-for-the-raspberry-pi-rpi-i2c-hub/]]
  
−
== I2C Hub for the Raspberry Pi ==
+
[[File:I2C-RPT-01_-6026_CCA-640px.jpg]]
  
 
<video type="youtube">R_YUetR83N4</video>
 
<video type="youtube">R_YUetR83N4</video>
  
−
[[File:I2C-RPT-01_-6026_CCA-640px.jpg]]
+
== I2C Hub for the Raspberry Pi ==
 +
 
 +
Four channel I2C Multiplexer
  
 
== Features ==
 
== Features ==
  
 
* I2C Hub / Repeater / Replicator / Multiplexer / De-multiplexer
 
* I2C Hub / Repeater / Replicator / Multiplexer / De-multiplexer
−
** PCA9544A IC
+
** [https://www.ti.com/lit/ds/symlink/pca9544a.pdf PCA9544A Datasheet]
 
** Controlled via I2C
 
** Controlled via I2C
 
** Multiple part vendors
 
** Multiple part vendors
Line 25: Line 27:
 
* Interrupt controller on each channel and host 100KHz/400KHz operation
 
* Interrupt controller on each channel and host 100KHz/400KHz operation
 
* On-board termination resistors
 
* On-board termination resistors
 +
 +
== Testing ==
 +
 +
* PCA9544 Programming
 +
* Run with [[DigIO16-I2C]] card on Hub Port #0
 +
* Verify that the Hub is seen from the Raspberry Pi
 +
* Note should be -y 0 for the older revision Raspberry Pis
 +
<pre>
 +
pi@raspi3 ~ $ sudo i2cdetect -y 1
 +
    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
 +
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
 +
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
70: -- 71 -- -- -- -- -- --
 +
</pre>
 +
* Shows that there is an I2C part at 0x71
 +
* Next, set the mux to channel #0
 +
<pre>
 +
pi@raspi3 ~ $ sudo i2cset -y 1 0x71 0x04 0x04
 +
</pre>
 +
* Verify that the hub is set to the port
 +
<pre>
 +
pi@raspi3 ~ $ sudo i2cdetect -y 1
 +
    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
 +
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
 +
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
 +
70: -- 71 -- -- -- -- -- --
 +
</pre>
 +
* This shows the two addresses of the DigIO16-I2C
 +
 +
* [https://github.com/land-boards/RasPi/blob/master/RPI-I2C-Hub/RPI-I2C-Hub.py Raspberry Pi Code] - Bounce a light across 8 LEDs on a MCP23017
 +
 +
=== Interrupts ===
 +
 +
* (4) Active Low Inputs
 +
** 3.3K pullups
 +
* Active Low Output
 +
** 3.3K pullup
 +
* On Raspberry Pi GPIO_17
 +
** Per [https://www.raspberrypi.org/documentation/hardware/raspberrypi/gpio/README.md Raspberry Pi > GPIO]
 +
* Each GPIO pin, when configured as a general-purpose input, can be configured as an interrupt source to the ARM.
 +
* [https://github.com/land-boards/RasPi/tree/master/RPI-I2C-Hub/IntrTestRPiHub Test code is here]
 +
 +
== Power ==
 +
 +
* Card power is 3.3V
 +
* The [https://elinux.org/RPi_Low-level_peripherals#Power_pins Raspberry Pi has 50mA max current limits]
 +
** PCA9544 draws 11 mA (max), terminators draw 2x1mA=2mA, 2x1.5mA=3mA, total of 16mA for the card
 +
** Leaving 50-17 = 34 mA
 +
 +
== Connectors ==
 +
 +
=== J1-J4 - I2C Slave ports 0-3 ===
 +
 +
* Right angle, 0.1" pitch pins
 +
* Pinout
 +
 +
# GROUND
 +
# Power (see H1-H4 Jumpers for explanation)
 +
# SDA
 +
# SCK
 +
# Interrupt* (Active Low)
 +
 +
=== P1 - Raspberry Pi Connector ===
 +
 +
* Card has a standard Raspberry Pi 26 pin connector which works with all Raspberry Pi models
 +
* Card has notch for original Pi audio jack clearance
 +
 +
* Pins used
 +
** 1,17 = 3.3V (50mA max)
 +
** 6,9,14,20,25 = GND
 +
** 3 = I2C SDA
 +
** 5 = I2C SCL
 +
** 11 = INT* = GPIO_17
 +
** Other pins are unused
 +
 +
[[file:raspberry-pi-40-pin-gpio-layout.jpg]]
 +
 +
== Jumpers ==
 +
 +
=== H1-H4 - I2C power source selection ===
 +
 +
* Installed - Raspberry Pi provides 3.3V power on the I2C connector power pin 2
 +
* Not installed - External device provides power on the I2C connector power pin 2
 +
 +
=== Power Options ===
 +
 +
* The card has flexible power options to power external I2C interfaces
 +
* 3.3V power to the Host Interface comes from the Raspberry Pi
 +
** This power can be used to drive external devices on the 4 I2C slave ports
 +
 +
==== Simple Method ====
 +
 +
* The "simplest" option is to provide 3.3V power to the external I2C from the RPI-I2C-HUB card
 +
** Install jumper to power the particular I2C interface from the RPI-I2C-HUB card
 +
* Warning - The [https://elinux.org/RPi_Low-level_peripherals#Power_pins Raspberry Pi has 50mA max current limits]
 +
** PCA9544 draws 11 mA (max), terminators draw 2x1mA=2mA, 2x1.5mA=3mA, total of 16mA for the card
 +
** Leaving 50-17 = 34 mA
 +
 +
==== External Power ====
 +
 +
* External interface can also have independent power
 +
** External interfaces can be at different voltage level from the I2C-RPT-01 card
 +
*** Example #1: Raspberry Pi voltage is 3.3V and interface to 5V I2C interfaces
 +
** Remove Jumper to power from external interface (3.3V or 5V)
 +
** In this case, the terminators get pulled up from the external interface
 +
 +
=== I2C Termination Resistors ===
 +
 +
* Card has 3.3K Termination resistors on SDA/SCL lines
 +
 +
[[file:RPI_I2C_TERMS.PNG]]
 +
 +
== Factory Test ==
 +
 +
[[File:P1416-720px.jpg]]
 +
 +
* Using [[RPI_PSOC5]] Card
 +
* Four [[I2CIO-8]] cards
 +
* Four 5 conductor I2C cables
 +
* Running [https://www.chiark.greenend.org.uk/~sgtatham/putty/ PuTTY]
 +
** 115,200 baud
 +
** Find serial port from Device Manager
 +
* 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
 +
R - Read EEPROM
 +
W - Write EEPROM
 +
D - Debug card
 +
B - Bounce LED across Card GPIOs
 +
? - Print this menu
 +
</pre>
 +
* Select 6 to select RPI-I2C-HUB card
 +
* Select D to test the card access of the four [[I2CIO-8]] cards
 +
* Select B to bounce across LEDs
 +
* Select T to test the Interrupt lines
 +
* Insert/remove slowly shunts on input lines of I2CIO-8 cards
 +
* Int light will go out momentarily and messages will be displayed
 +
* Messages will be like
 +
<pre>
 +
Input changed on channel 0 value = 0
 +
Input changed on channel 0 value = 1
 +
Input changed on channel 1 value = 0
 +
Input changed on channel 1 value = 2
 +
Input changed on channel 2 value = 0
 +
Input changed on channel 2 value = 8
 +
Input changed on channel 3 value = 0
 +
Input changed on channel 3 value = 4
 +
</pre>
 +
 +
=== Alternate Test Setup ===
 +
 +
[[File:I2C-RPT-01-Demo01-512px.jpg]]
 +
 +
=== Test Steps ===
 +
 +
* Hook up Raspberry Pi to Ethernet
 +
* Ethernet is using static IP
 +
* Connect (4) I2CIO-8 cards (Rev X2 or later add Interrupt line)
 +
* Set I2CIO-8 cards addresses to 000
 +
* Terminator jumpers not present
 +
* Use 5-pin 1:1 cables
 +
* Power up the Pi (using puTTY)
 +
* Verify all 4 I2CIO-8 cards have INT LEDs illuminated
 +
* Log onto Pi
 +
* Test code is here
 +
* Enter
 +
<pre>
 +
cd ~/RasPi/RPI-I2C-Hub/R-Hub-Intr-4x8
 +
sudo python R-Hub-Intr-4x8.py
 +
</pre>
 +
 +
* Will cycle through the LEDs on all four cards
 +
* Insert/remove slowly (every 2 secs or so) shunts on input lines of I2CIO-8 cards
 +
* Int light will go out momentarily until message is displayed
 +
* Messages will be like
 +
<pre>
 +
Input changed on channel 0 value = 0
 +
Input changed on channel 0 value = 1
 +
Input changed on channel 1 value = 0
 +
Input changed on channel 1 value = 2
 +
Input changed on channel 2 value = 0
 +
Input changed on channel 2 value = 8
 +
Input changed on channel 3 value = 0
 +
Input changed on channel 3 value = 4
 +
</pre>
 +
 +
* Verify all channels show input change (values do not matter)
  
 
== Schematic ==
 
== Schematic ==
Line 33: Line 238:
  
 
* [https://github.com/land-boards/RasPi/tree/master/RPI-I2C-Hub Git Hub Repo]
 
* [https://github.com/land-boards/RasPi/tree/master/RPI-I2C-Hub Git Hub Repo]
 +
 +
== Checkout - Rev X1 ==
 +
 +
* Changed base address to 0x71
 +
* Added some extra pins marking
  
 
== Assembly Sheet ==
 
== Assembly Sheet ==
  
 
* [[RPI-I2C-HUB Assembly Sheet]]
 
* [[RPI-I2C-HUB Assembly Sheet]]

Latest revision as of 14:18, 2 April 2022

Tindie-mediums.png

I2C-RPT-01 -6026 CCA-640px.jpg

I2C Hub for the Raspberry Pi

Four channel I2C Multiplexer

Features

  • I2C Hub / Repeater / Replicator / Multiplexer / De-multiplexer
    • PCA9544A Datasheet
    • Controlled via I2C
    • Multiple part vendors
    • Devices with the same address can be attached to different ports
  • Host I2 port goes to Raspberry Pi I2C lines
    • 3.3V host operation
  • Four I2C slave ports
    • I2C ports can use the Raspberry Pi or have their own power (power source select jumper)
    • A Raspberry PI which runs 3.3V can control an I2C device which runs at 5V
  • Voltage translation between the ports
    • I2C ports can be 3.3V or 5V
  • Fits in any Raspberry Pi model
    • Cutout for Model B RCA video jack
  • Interrupt controller on each channel and host 100KHz/400KHz operation
  • On-board termination resistors

Testing

  • PCA9544 Programming
  • Run with DigIO16-I2C card on Hub Port #0
  • Verify that the Hub is seen from the Raspberry Pi
  • Note should be -y 0 for the older revision Raspberry Pis
pi@raspi3 ~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- 71 -- -- -- -- -- --
  • Shows that there is an I2C part at 0x71
  • Next, set the mux to channel #0
pi@raspi3 ~ $ sudo i2cset -y 1 0x71 0x04 0x04
  • Verify that the hub is set to the port
pi@raspi3 ~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- 71 -- -- -- -- -- --
  • This shows the two addresses of the DigIO16-I2C

Interrupts

  • (4) Active Low Inputs
    • 3.3K pullups
  • Active Low Output
    • 3.3K pullup
  • On Raspberry Pi GPIO_17
  • Each GPIO pin, when configured as a general-purpose input, can be configured as an interrupt source to the ARM.
  • Test code is here

Power

Connectors

J1-J4 - I2C Slave ports 0-3

  • Right angle, 0.1" pitch pins
  • Pinout
  1. GROUND
  2. Power (see H1-H4 Jumpers for explanation)
  3. SDA
  4. SCK
  5. Interrupt* (Active Low)

P1 - Raspberry Pi Connector

  • Card has a standard Raspberry Pi 26 pin connector which works with all Raspberry Pi models
  • Card has notch for original Pi audio jack clearance
  • Pins used
    • 1,17 = 3.3V (50mA max)
    • 6,9,14,20,25 = GND
    • 3 = I2C SDA
    • 5 = I2C SCL
    • 11 = INT* = GPIO_17
    • Other pins are unused

Raspberry-pi-40-pin-gpio-layout.jpg

Jumpers

H1-H4 - I2C power source selection

  • Installed - Raspberry Pi provides 3.3V power on the I2C connector power pin 2
  • Not installed - External device provides power on the I2C connector power pin 2

Power Options

  • The card has flexible power options to power external I2C interfaces
  • 3.3V power to the Host Interface comes from the Raspberry Pi
    • This power can be used to drive external devices on the 4 I2C slave ports

Simple Method

  • The "simplest" option is to provide 3.3V power to the external I2C from the RPI-I2C-HUB card
    • Install jumper to power the particular I2C interface from the RPI-I2C-HUB card
  • Warning - The Raspberry Pi has 50mA max current limits
    • PCA9544 draws 11 mA (max), terminators draw 2x1mA=2mA, 2x1.5mA=3mA, total of 16mA for the card
    • Leaving 50-17 = 34 mA

External Power

  • External interface can also have independent power
    • External interfaces can be at different voltage level from the I2C-RPT-01 card
      • Example #1: Raspberry Pi voltage is 3.3V and interface to 5V I2C interfaces
    • Remove Jumper to power from external interface (3.3V or 5V)
    • In this case, the terminators get pulled up from the external interface

I2C Termination Resistors

  • Card has 3.3K Termination resistors on SDA/SCL lines

RPI I2C TERMS.PNG

Factory Test

P1416-720px.jpg

  • Using RPI_PSOC5 Card
  • Four I2CIO-8 cards
  • Four 5 conductor I2C cables
  • Running PuTTY
    • 115,200 baud
    • Find serial port from Device Manager
  • 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
R - Read EEPROM
W - Write EEPROM
D - Debug card
B - Bounce LED across Card GPIOs
? - Print this menu
  • Select 6 to select RPI-I2C-HUB card
  • Select D to test the card access of the four I2CIO-8 cards
  • Select B to bounce across LEDs
  • Select T to test the Interrupt lines
  • Insert/remove slowly shunts on input lines of I2CIO-8 cards
  • Int light will go out momentarily and messages will be displayed
  • Messages will be like
Input changed on channel 0 value = 0
Input changed on channel 0 value = 1
Input changed on channel 1 value = 0
Input changed on channel 1 value = 2
Input changed on channel 2 value = 0
Input changed on channel 2 value = 8
Input changed on channel 3 value = 0
Input changed on channel 3 value = 4

Alternate Test Setup

I2C-RPT-01-Demo01-512px.jpg

Test Steps

  • Hook up Raspberry Pi to Ethernet
  • Ethernet is using static IP
  • Connect (4) I2CIO-8 cards (Rev X2 or later add Interrupt line)
  • Set I2CIO-8 cards addresses to 000
  • Terminator jumpers not present
  • Use 5-pin 1:1 cables
  • Power up the Pi (using puTTY)
  • Verify all 4 I2CIO-8 cards have INT LEDs illuminated
  • Log onto Pi
  • Test code is here
  • Enter
cd ~/RasPi/RPI-I2C-Hub/R-Hub-Intr-4x8
sudo python R-Hub-Intr-4x8.py
  • Will cycle through the LEDs on all four cards
  • Insert/remove slowly (every 2 secs or so) shunts on input lines of I2CIO-8 cards
  • Int light will go out momentarily until message is displayed
  • Messages will be like
Input changed on channel 0 value = 0
Input changed on channel 0 value = 1
Input changed on channel 1 value = 0
Input changed on channel 1 value = 2
Input changed on channel 2 value = 0
Input changed on channel 2 value = 8
Input changed on channel 3 value = 0
Input changed on channel 3 value = 4
  • Verify all channels show input change (values do not matter)

Schematic

Example Code/Driver

Checkout - Rev X1

  • Changed base address to 0x71
  • Added some extra pins marking

Assembly Sheet

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