I2C-RPT-08

Features

• I2C Hub / Repeater / Replicator / Multiplexer / De-multiplexer / Switch
  • PCA9548A Datasheet
  • Eight I2C Ports
  • 100KHz/400KHz operation
  • I2C Base Address 0x70
    • Offset addresses 0x70-0x77
• Host port
  • Controlled via I2C
  • 3.3V or 5V host operation
  • Can power slave cards if they are at the same voltage
• 3.3V or 5V slave ports operation
  • Removable jumper(s) to supply power from slave
• Voltage translation between the ports
  • Ex: a Raspberry Pi which runs 3.3V can control I2C devices which run at 5V
• On-board 2.2K termination resistors
• 49x49mm form factor
• 4 solid 4-40 mounting holes
• Drivers/Example Code
  • Arduino driver and example code
  • Raspberry Pi example code

Connectors

• 0.1" pitch connections
• Search ebay for Dupont headers
• Search ebay for Dupontwire jumper cable
• The slave I2C connectors are (4) 2x6 right angle 0.1" pitch headers
• Two ports per 2x6 connector
• Two of the pins are for power to or from the I2C connector
• The other four pins are for the I2C interface

H1-H8 - Power to/from I2C Connectors

• Install shunt to power the I2C slave card from the I2C-RPT-08 Card
  • Default factory ships as installed to power external I2C interfaces from the card
• Remove shunt to power interface externally
  • Need to remove if external voltage is different level or sourced externally
• H1 - PORT #0
• ...
• H8 = PORT #7

H9 - I2C Slave Address Jumpers

• A0-A2
• Install all 3 jumpers for address 0x70
• Remove all three jumpers for address 0x77

J1 - Host I2C Connection

1. GND (GND pin marked)
2. 3.3V or 5V VCC
3. SDA
4. SCL

J2-J5 - Slave I2C Connections (x8)

1. GND
2. 3.3V or 5V VCC (Power Out - if jumper 1-2 installed, Power in - if jumper 1-2 is not installed)
3. SDA
4. SCL (Board marked with SCK)

Jumpers

A0-A2 - Multiplexer I2C Base Address

• Install for Ax = 0 (factory default address = 0)
• Remove for Ax = 1

Schematic

• I2C-RPT-08 Rev X1 Schematic
• I2C-RPT-08 Rev 2 Schematic

Drivers/Example Code

• Arduino Driver code - Github repo
• Arduino Example code - Github repo
• Raspberry Pi Example Code - Github repo

Programming Note

• The mux chip allows multiple or single I2C ports to be written at the same time
  • To only enable one port at a time make sure you disable a channel after use or disable last channel used before enabling new channel

Arduino Driver Functions

LandBoards_I2CRPT08(void) - Constructor
void begin(uint8_t addr) - Set mux I2C address (offset or absolution 0x70-0x77)
void begin() - Assume I2C address = 0x20
void setI2CChannel(uint8_t chNum, uint8_t enableFlag) - chNum = 0x0-0x7. I2CRPT08_MUXCH_DISABLE, I2CRPT08_MUXCH_ENABLE
uint8_t getI2CChannel(void) - Read entire channel status - useful for testing

Testing

Test Station Hardware

• Arduino Based Test Station
  • Built in I2C mux on BLACK-PILL-HUB is set to offset=0x1 so it does not conflict with I2C address of UUT
  • Cabling
    • UUT J1 Host connects to I2C port (J7) on the BLACK-PILL-HUB
• Uses 8x of I2CIO-8 cards
  • Cabling 4 wire from I2CIO-8 cards J1 to UUT I2C #0-#7
  • Address jumpers are all installed for base address of 0x20
• On Unit Under Test (UUT)
  • Install (3) h9 jumpers into A0-A2 for card I2C address = 0x70

Test Procedure

• Run puTTY
  • COM port from Device Manager
  • 9600 baud
  • No parity
  • No handshake
• Menu will display

Checking if EEPROM is present on UUT...EEPROM is not present on UUT
Count of I2C devices in range 0x20-0x27 on UUT = 0
Found external I2C mux card
Select I2C Mux board type
1 - I2C-RPT-01 board
2 - I2C-RPT-08 board

• Enter 2
• Replies with

Init I2C-RPT-08 card
I2CIO8 card #0 was detected
I2CIO8 card #1 was detected
I2CIO8 card #2 was detected
I2CIO8 card #3 was detected
I2CIO8 card #4 was detected
I2CIO8 card #5 was detected
I2CIO8 card #6 was detected
I2CIO8 card #7 was detected
C=Card Tests, D=Direct, E=EEPROM, I=access Internal DIGIO32

• Verify that all 8 I2CIO-8 cards were detected

Internal Tests

• Select C to test card
• Select I to run internal tests
  • Tests I2C interface to UUT

UUT Internal card tests
Test PASS = 1, FAIL = 0

Bounce LEDS

• Select B to bounce LED across LEDs on all 4 I2CIO-8 cards
• Verify all 16 LEDs blink

Bounce a bit across outputs
Bouncing LEDs I2C-RPT-01 and I2CIO8 - any key to stop
Hit any key to stop test

• Hit any key to stop blinking

Test Station Software

• ODAS Tester Github Repo

Issues

Rev 2

• Rev 2 fixes SCK -> SCL
• Adds port numbers to slave connectors
• Move SMT fiducials to bottom (lot of resistors on the rear of card)
• Combined Power jumpers into the Port jumpers
• Moved J2 away from mounting screw
• Add silkscreen details
• Removed C2 from front of board
• Added 3D model for all parts
• KiCad 6

Rev 1 Issues

• No functional issues
• Silkscreen shows SCK, should be SCL

Assembly Sheet

• I2C-RPT-08 Assembly Sheet - Rev X1
• I2C-RPT-08 Rev 2 Assembly Sheet - Rev 2