KS0497 Keyestudio V4.0 Development Board(Compatible With Arduino Uno)

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The processor core of Keyestudio V4.0 development board is ATMEGA328P-PU , fully compatible with ARDUINO UNO REV3.
It has 14 digital input/output pins(of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, 1 ICSP header, and a reset button. The built-in ICSP port can burn the firmware for ATMEGA328P-PU directly. We can plug in power by USB wire, DC head and Vin GND pins.


  • Microcontroller: ATMEGA328P-PU
  • USB serial chip:CP2102
  • Operating Voltage: 5V
  • Input Voltage (recommended):DC 7-12V
  • Digital I/O Pins: 14 (D0-D53)
  • PWM Digital I/O Pins:6 (D3 D5 D6 D9 D10 D11)
  • Analog Input Pins: 6(A0-A5)
  • DC Current per I/O Pin: 20 mA
  • DC Current for 3.3V Pin: 50 mA
  • Flash Memory: 32 KB (ATMEGA328P-PU) of which 0.5 KB used by bootloader
  • Clock Speed:16 MHz

Pin Interfaces


1 ICSP (In-Circuit Serial Programming) Header

the AVR, an Arduino micro-program header consisting of MOSI, MISO, SCK, RESET, VCC, and GND. It is often called the SPI (serial peripheral interface) and can be considered an "extension" of the output. In fact, slave the output devices to the SPI bus host. When connecting to PC, program the firmware to ATMEGA328P-PU.

2 Power LED Indicator

Powering the Arduino, LED on means that your circuit board is correctly powered on. If LED is off, connection is wrong.

3 Digital I/O

Arduino MEGA has 14 digital input/output pins (of which 6 can be used as PWM outputs).These pins can be configured as digital input pin to read the logic value (0 or 1). Or used as digital output pin to drive different modules like LED, relay, etc. Using pinMode(), digitalWrite(), and digitalRead() functions.




Reference voltage (0-5V) for analog inputs. Used with analogReference(). Configures the reference voltage used for analog input (i.e. the value used as the top of the input range).

6 RESET Button

You can reset your Arduino board


IIC communication pin


IIC communication pin

8 RESET Button

You can reset your Arduino board,

9 D13 LED

There is a built-in LED driven by digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off.

10 USB Connection

Arduino board can be powered via USB connector. All you needed to do is connecting the USB port to PC using a USB cable.

11 CP2102

USB serial chip, translate the USB signal of computer into serial signal


Onboard you can find the label: TX (transmit) When Arduino board communicates via serial port, send the message, TX led flashes.


Onboard you can find the label: RX(receive ) When Arduino board communicates via serial port, receive the message, RX led flashes.

14 Crystal Oscillator

How does Arduino calculate time? by using a crystal oscillator. The number printed on the top of the Arduino crystal is 16.000H9H. It tells us that the frequency is 16,000,000 Hertz or 16MHz.

15 Voltage Regulator

To control the voltage provided to the Arduino board, as well as to stabilize the DC voltage used by the processor and other components. Convert an external input DC7-12V voltage into DC 5V, then switch DC 5V to the processor and other components.

16 DC Power Jack

Arduino board can be supplied with an external power DC7-12V from the DC power jack.

17 Microcontroller

Each Arduino board has its own microcontroller. You can regard it as the brain of your board. The main IC (integrated circuit) on the Arduino is slightly different from the panel pair. Microcontrollers are usually from ATMEL. Before you load a new program on the Arduino IDE, you must know what IC is on your board. This information can be checked at the top of IC.


This pin on the board provides the voltage reference with which the microcontroller operates. A properly configured shield can read the IOREF pin voltage and select the appropriate power source or enable voltage translators on the outputs for working with the 5V or 3.3V.

19 RESET Header

Connect an external button to reset the board. The function is the same as reset button.

20 Power Pin 3V3

A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA.

21 Power Pin 3V3

Provides 5V output voltage

22 Vin

You can supply an external power input DC7-12V through this pin to Arduino board.

23 Power Pin 3V3

Onboard has 6 analog inputs, labeled A0 to A5.

Specialized Functions of Some Pins:

  • Serial Communication: D0 (RX) and D1 (TX)
  • PWM Pins (Pulse-Width Modulation): D3 D5 D6 D9 D10 D11
  • External Interrupts: D2 (interrupt 0), D3 (interrupt 1)
  • SPI communication: D10 (SS), D13 (SCK), D11 (MOSI), D12 (MISO).
  • These pins support SPI communication using theSPI library. The SPI pins are also broken out on the ICSP header, which is physically compatible with the Arduino Uno.
  • IIC communication: A4 (SDA); A5 (SCL). Support TWI communication using the Wire library.

Windows System

Installing Arduino IDE

When getting this control board, we need to install Arduino IDE Enter the website https://www.arduino.cc/, click thumb and thumb


Select the version you want to download, the latest version could be downloaded.


Alternatively, you could select previous release. In this project, we use 1.8.12 version.


Clickthumb to view the below page


Click thumb to download an installer of Arduino 1.8.12 version,which needs to be installed manually. When you tap thumb,a zip file of Arduino 1.8.12 version will be directly downloaded, and you only need to unzip it to finish installation.


Click thumbicon to download Arduino IDE.

Installing driver

Let’s install the driver of keyestudio V4.0 development board. The USB-TTL chip on V4.0 development board adopts CP2102 serial chip. The driver program of this chip is included in Arduino 1.8 version and above, which is convenient. Plug on USB port of board, the computer can recognize the hardware and automatically install the driver of CP2102.

Note: If the version of Arduino IDE you download is below 1.8, you need to download the driver of CP2102.

Download the driver of CP2102: https://fs.keyestudio.com/CP2102-WIN

If install unsuccessfully, or you intend to install manually, open the device manager of computer. Right click Computer----- Properties----- Device Manager.


There is a yellow exclamation mark on the page, which implies installing the driver of CP2102 unsuccessfully. Then we double click the hardware and update the driver.


Click “OK” to enter the following page, click “browse my computer for updated driver software”, find out the installed or downloaded ARDUINO software. As shown below:


There is a DRIVERS folder in Arduino software installed package(thumb), open driver folder and you can see the driver of CP210X series chips.

We click “Browse”, then find out the driver folder, or you could enter “driver” to search in rectangular box, then click “next”, the driver will be installed successfully. (I place Arduino software folder on the desktop, you could follow my way)


Open device manager, we will find the yellow exclamation mark disappear. The driver of CP2102 is installed successfully.


Arduino IDE Setting

Clickthumb icon,open Arduino IDE.


To avoid the errors when uploading the program to the board, you need to select the correct Arduino board that matches the board connected to your computer. Then come back to the Arduino software, you should click Tools→Board, select the board. (as shown below)


Then select the correct COM port (you can see the corresponding COM port after the driver is successfully installed)



Before uploading the program to the board, let’s demonstrate the function of each symbol in the Arduino IDE toolbar.

A- Used to verify whether there is any compiling mistakes or not. B- Used to upload the sketch to your Arduino board. C- Used to create shortcut window of a new sketch. D- Used to directly open an example sketch. E- Used to save the sketch. F- Used to send the serial data received from board to the serial monitor.

Start your first program

Open the file to select Example, choose BLINK from BASIC, as shown below:



Set board and COM port, the corresponding board and COM port are shown on the lower right of IDE.


Click 0486-20.png to start compiling the program, check errors.


Click 0486-23.pngto upload the program, upload successfully.


Upload the program successfully, the onboard LED lights on for 1s, lights off for 1s. Congratulation, you finish the first program.

MAC System

Install Arduino IDE on MAC System

The installation instruction is as same as the chapter 5.1, as shown below:


Download the Driver of CP2102


How to Install the Driver of CP2102

The following link is for your reference:


Arduino IDE Setting

The setting method is as same as the chapter 5.3 except from COM port, as shown below.