RPI-I2C-HUB

From Land Boards Wiki
Jump to navigation Jump to search

Tindie-mediums.png

I2C Hub for the Raspberry Pi

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

Features

  • I2C Hub / Repeater / Replicator / Multiplexer / De-multiplexer
    • PCA9544A IC
    • 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 Per Raspberry Pi > GPIO Each GPIO pin, when configured as a general-purpose input, can be configured as an interrupt source to the ARM. Test code is here

Schematic

Example Code/Driver

Assembly Sheet