I2C-RPT

Features

• I2C Hub / Repeater / Replicator / Multiplexer / De-multiplexer / Switch
  • PCA9544A Datasheet IC Multiple vendors
  • Four I2C Ports
  • 100KHz/400KHz operation
  • I2C Address fixed at 0x70
• Host port
  • Controlled via I2C
  • 3.3V or 5V host operation
  • 3.3V or 5V slave ports 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
  • Example: A Raspberry PI which runs 3.3V can control an I2C device which runs at 5V
• Interrupt line on each channel and host
• 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

I2C Termination Resistors

• Card has 2.2K Termination resistors on SDA/SCL lines

H1-H4 - Headers

• Jumpers
  • H1 = I2C #0 Power
  • H2 = I2C #1 Power
  • H3 = I2C #2 Power
  • H4 = I2C #3 Power

Power Options

• The card has flexible power options
  • The "simplest" option is to provide power to the external I2C from the card
    • Install jumper to power the particular I2C interface from the card
  • External interface can also have independent power
    • External interfaces can be at different voltage level from this card
      • Example #1: Card Host voltage can be 5V (Arduino) and interface to 3.3V 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

Connectors

• 0.1" pitch connections
• Search ebay for Dupont headers
• Search ebay for Dupontwire jumper cable
• The slave I2C connectors are (4) 1x5 right angle 0.1" pitch headers

J1-J4 - I2C Slave ports

• Ports
  • J1 = I2C Port #0
  • J2 = I2C Port #1
  • J3 = I2C Port #2
  • J4 = I2C Port #3
• Pinout

1. GND
2. VCC (If Hx is installed, card powers this pin)
3. SDA
4. SCL
5. INT*

J5 - I2C to/from Host port

• Power comes in this connector
  • Voltage matches signal levels
  • 2.2K Ohm terminated
  • I2C address is fixed at 0x70

1. GND (G)
2. VCC (V) - Power into the card
3. SDA (D)
4. SCL (C)
5. INT* (I) - Interrupt (active low)

Schematic

• Schematic

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 J5 Host connects to I2C port (J7) on the BLACK-PILL-HUB
    • UUT J5 Host INT pin connects via jumper cable to PB6-SIG
• Uses 4x of I2CIO-8 cards
  • Cabling 5 wire from I2CIO-8 cards J1 to UUT I2C #0-#3
  • Address jumpers are all installed for base address of 0x20
• On Unit Under Test (UUT)
  • Card I2C address = 0x70
  • Install H1-H4 shunts
    • Powers I2CIO-8 cards from UUT

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 1
• Replies with

Init I2C-RPT-01 card
I2CIO8 card #0 was detected
I2CIO8 card #1 was detected
I2CIO8 card #2 was detected
I2CIO8 card #3 was detected
C=Card Tests, D=Direct, E=EEPROM, I=access Internal DIGIO32

• Verify that all 4 I2CIO-8 cards were detected
• Select C to test card
• Select B to bounce LED across LEDs on all 4 I2CIO-8 cards
• Verify all 16 LEDs blink
• Hit any key to stop blinking
• Hit T to test card
• Move jumper across I2CIO-8 card input jumpers
• Verify action on the screen
• Hit any key to stop test
• Mark TEST block on rear of card if passed

Test Station Software

• ODAS Tester Github Repo

I2C Timing

Drivers/Example Code

• GitHub Repo - Arduino Driver code
  • How to import a ZIP library
• Github Repo - Example code
• Raspberry Pi Example Code

Arduino Driver Functions

LandBoards_I2CRPT01(void) - Class Constructor
void begin() - Assumes I2C address = 0x70
void begin(uint8_t addr) - Offset address (adds base)
void setI2CChannel(uint8_t) - #defines are I2CRPT01_CH0 - I2CRPT01_CH3, I2CRPT01_NONE
uint8_t getI2CChannel(void)
uint8_t getIntStatus(void)

PCA9544 Control Register

PCA9544 Status Register

Issues

Rev X3 Issues

• Fixed SCK silkscreen to be SCL
• No issues found

Rev X2 Issues

• Board functions fine
• Silkscreen SCK should be SCL

Rev X1 Issues =

• SDA/SCL pins are swapped from "normal" pinout

Assembly Sheet

• I2C-RPT-01 Assembly Sheet