10 min

Transform your projects into hubs of efficiency with AP33771 and ATmega644

USB-C sink – Uniting speed, power, and style!

USB-C Sink 3 Click with EasyAVR v7

Published Nov 13, 2023

Click board™

USB-C Sink 3 Click

Development board

EasyAVR v7


NECTO Studio



Revolutionize your project experience with our USB-C sink solution, paving the way for faster data transfers and smarter power management.



Hardware Overview

How does it work?

USB-C Sink 3 Click is based on the AP33771, a high-performance USB PD sink controller from Diodes Incorporated. It supports up to eight voltage selections alongside ten different power range selections. In addition to selected voltages, both fixed PDO and PPS APDO in the PD source adapter are supported in the AP33771 search algorithm. The PD controller supports OVP with auto-restart, one-time programming (OTP) ROM for main firmware, and power capability selection. The onboard FAULT LED serves as a visual presentation of the negotiation mismatch. USB-C Sink 3 Click is equipped with a VSINK, an external power supply terminal that comes with a pair of MOSFETs, according to the AP33771’s driver for N-MOS VBUS power switch support. The PD controller can control the external NMOS switch ON or OFF. The USB-C connector acts as a PD-IN discharge path terminal with a USB Type-C configuration channels 1 and 2. The presence of the power supply on the USB C is indicated over

the VBUS LED. The USB-C Sink 3 Click comes with a VSEL three 2-position jumpers labeled 0, 1, and 2 to select the desired target voltage. I/O and FIX(ed) sides allow you to choose between hardware and software target voltage selection in eight positions and a target voltage range from 5V up to 17.2V. The VSEL is set to I/O by default, where you can set logic states to the three IO pins over the TCA9536, a remote 4-bit I2C, and SMBus I/O expander with configuration registers from Texas Instruments. The table of the combination of the positions and the resulting target voltages is printed at the bottom of the Click board™. You can use fixed jumper positions by setting the jumpers as you like, where I/O acts as a 0 and 3V3 as a 1 position. The 5V and 3.3V LDO voltage output can be measured over the V5V and V3V pads and voltage feedback over the VFB pad. To select the desired power, there is the MCP41100T, a digital potentiometer with an SPI interface from Microchip. Selecting the corresponding resistance

value on the digital potentiometer allows you to choose one of the current capabilities ranging from 12W to 100W. The table with the expected resistance and the resulting current is printed at the bottom of the Click board™. In addition, you can solder a standard resistor by soldering it on RES resistor pads. For that purpose, you should set the PSEL jumper to a RES position, as it is set to a POT position by default. USB-C Sink 3 Click uses a standard 2-Wire I2C interface of the MCP41100T to communicate with the host MCU. One of the main features of the USB-C Sink 3 Click is the ability to track the VBUS voltage over the AN pin of the mikroBUS™ socket. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

USB-C Sink 3 Click hardware overview image

Features overview

Development board

EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more

efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)

connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

EasyAVR v7 horizontal image

Microcontroller Overview

MCU Card / MCU




MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Analog Output
SPI Chip Select
SPI Clock
Power Supply
I2C Clock
I2C Data

Take a closer look


USB-C Sink 3 Click Schematic schematic

Step by step

Project assembly

EasyAVR v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.

EasyAVR v7 front image hardware assembly
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyAVR v7 Access DIP MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for USB-C Sink 3 Click driver.

Key functions:

  • usbcsink3_set_voltage - USB-C Sink 3 set the voltage function.

  • usbcsink3_set_power - USB-C Sink 3 set the power function.

  • usbcsink3_get_vbus - USB-C Sink 3 get VBUS function.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * @file main.c
 * @brief USB-C Sink 3 Click example
 * # Description
 * This example demonstrates the use of USB-C Sink 3 Click board™ 
 * by setting DC power requests and control for Type-C connector-equipped devices (TCD).
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes SPI, I2C and ADC modules and log UART.
 * After driver initialization the app set default settings:
 * Voltage Selection: 5 [V] and Power: 15.0 [W].
 * ## Application Task
 * In this example, the app configures Power Data Objects (PDO) 
 * highest priority profile and requests power from a standard USB PD source adapter.
 * It interprets power input requirements (voltage/current and maximum power) from the TCD.
 * The example uses two configurations: 
 *  - Voltage 5 [V] and Power 15.0 [W]
 *  - Voltage 9 [V] and Power 18.0 [W]
 * Results are being sent to the Usart Terminal where you can track their changes.
 * @note
 * FAULT LED flickering notified of the system status:
 *  - Charging: Breathing light (2 sec dimming), 1 cycle is 4 sec.
 *  - Fully charged: Continuously lit Charging current < 500mA.
 *  - Mismatch: 1s flicker Voltage or power mismatch. Non-PD power source, 1 cycle is 2sec.
 *  - Fault: 300ms flicker OVP, 1 cycle is 600ms.
 * @author Nenad Filipovic

#include "board.h"
#include "log.h"
#include "usbcsink3.h"

static usbcsink3_t usbcsink3;
static log_t logger;

void application_init ( void )
    log_cfg_t log_cfg;  /**< Logger config object. */
    usbcsink3_cfg_t usbcsink3_cfg;  /**< Click config object. */

     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    usbcsink3_cfg_setup( &usbcsink3_cfg );
    USBCSINK3_MAP_MIKROBUS( usbcsink3_cfg, MIKROBUS_1 );
    err_t init_flag = usbcsink3_init( &usbcsink3, &usbcsink3_cfg );
    if ( ( I2C_MASTER_ERROR == init_flag ) || ( SPI_MASTER_ERROR == init_flag ) )
        log_error( &logger, " Communication init." );
        for ( ; ; );
    Delay_ms( 100 );
    if ( USBCSINK3_ERROR == usbcsink3_default_cfg ( &usbcsink3 ) )
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    Delay_ms( 100 );
    log_info( &logger, " Application Task " );
    log_printf( &logger, " ------------------------\r\n" );
    Delay_ms( 1000 );

void application_task ( void )
    static float voltage = 0.0;
    if ( ( USBCSINK3_OK == usbcsink3_set_voltage( &usbcsink3, USBCSINK3_VTG_SEL_5V ) ) &&
         ( USBCSINK3_OK == usbcsink3_set_power( &usbcsink3, USBCSINK3_PWR_SEL_15W ) ) )
        log_printf( &logger, " Output:\r\nVoltage: 5.0 [V]\r\nPower: 15.0 [W]\r\n" );
        log_printf( &logger, " - - - - - -  - - - - - -\r\n" );
        Delay_ms( 1000 );
        usbcsink3_get_vbus ( &usbcsink3, &voltage );
        log_printf( &logger, " VBUS : %.1f [V]\r\n", voltage );
        log_printf( &logger, " ------------------------\r\n" );
        Delay_ms( 5000 );
    if ( ( USBCSINK3_OK == usbcsink3_set_voltage( &usbcsink3, USBCSINK3_VTG_SEL_9V ) ) &&
         ( USBCSINK3_OK == usbcsink3_set_power( &usbcsink3, USBCSINK3_PWR_SEL_18W ) ) )
        log_printf( &logger, " Output:\r\nVoltage: 9.0 [V]\r\nPower: 18.0 [W]\r\n" );
        log_printf( &logger, " - - - - - -  - - - - - -\r\n" );
        Delay_ms( 1000 );
        usbcsink3_get_vbus ( &usbcsink3, &voltage );
        log_printf( &logger, " VBUS : %.1f [V]\r\n", voltage );
        log_printf( &logger, " ------------------------\r\n" );
        Delay_ms( 5000 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

// ------------------------------------------------------------------------ END

Additional Support