Read the PD status

What this example shows

Once a second, the sketch asks the HUSB238 whether a USB-C PD charger is attached. If one is, it prints the voltage the charger agreed to and the charger's current for that voltage. If not, it prints Not attached. The sketch only reads from the HUSB238 and changes nothing on the board.

Wire SDA, SCL and GND to your controller's I2C pins as in the Quick Start, and plug a charger into the board with the slide switch on.

The example code

This is Basic.ino from the pinned library, without its header comment. The sketch itself is exactly as shipped.

Select Board

Basic.ino

#include "HUSB238-SOLDERED.h"

Husb238 husb238;

void setup()
{
    Serial.begin(115200);
    husb238.begin();
}

void loop()
{
    if (husb238.isAttached())
    {
        Serial.print("Attached, voltage: ");
        Serial.print(husb238.getPDSrcVoltage());
        Serial.print(" V, current: ");
        Serial.print(husb238.getPDSrcCurrent());
        Serial.println(" A");
    }
    else
    {
        Serial.println("Not attached");
    }

    delay(1000);
}

Expected result: open the Serial Monitor at 115200 baud. With a PD charger attached, a new line appears every second. It starts with Attached, voltage:, then gives the agreed voltage in volts and the charger's current in amps. When no PD charger is attached, each line reads Not attached. The numbers depend on your charger and on the DIP switches.

With a 65 W USB-C PD charger that offers 20 V at 3.25 A, and every DIP switch off, the Serial Monitor shows:

Serial MonitorAutoscrollShow timestampNewline115200 baud

Message (Enter to send message to the board)

Attached, voltage: 20.00 V, current: 3.25 A
Attached, voltage: 20.00 V, current: 3.25 A
Attached, voltage: 20.00 V, current: 3.25 A
Attached, voltage: 20.00 V, current: 3.25 A

Functions used

Husb238(uint8_t _address = HUSB238_I2C_ADDR, TwoWire &_wire = Wire)returns None

Creates the HUSB238 object. It only stores the I2C address and the Wire port. Nothing is read from or written to the chip until the first read or request function.

ReturnsConstructor; no return value.

Parameters

Name	Type	Description
_address	uint8_t	I2C address. Defaults to HUSB238_I2C_ADDR, which is 0x08, the board's fixed address.
_wire	TwoWire &	The Wire interface to use. Defaults to Wire.

begin()returns void

Starts I2C communication by calling begin() on the Wire port the object was created with.

ReturnsNothing.

isAttached()returns bool

Checks whether a PD source is attached. It reads the HUSB238's PD_STATUS1 register and tests its attach bit. A read that gets no answer counts as 0, so it returns false.

Returnstrue if a PD source is attached, false otherwise.

getPDSrcVoltage()returns float

Reads the currently negotiated source voltage from the PD_STATUS0 register.

ReturnsThe voltage in volts: 5, 9, 12, 15, 18 or 20, or 0 if no source is attached.

getPDSrcCurrent()returns float

Reads the source's maximum current for the negotiated contract from the PD_STATUS0 register.

ReturnsThe current in amps, one of the HUSB238's steps from 0.5 to 5.0 A.

Putting it together

Husb238 husb238; uses the default address 0x08 and Wire, and begin() starts the bus. In loop(), isAttached() decides which line to print. When a source is attached, getPDSrcVoltage() and getPDSrcCurrent() each read the status register once, and delay(1000) keeps it to one line a second.

To change the voltage from code, see Request a voltage.

SourceOpen the verified Arduino exampleView the exact source used by this page.examples/Basic/Basic.ino