Wi-Fi & Bluetooth LE SoC NANO (WBRU)

The Tuya Sandwich Wi-Fi and Bluetooth Low Energy (LE) combo SoC has Tuya’s WBRU network module as a microcontroller, which is designed to help you easily prototype your IoT ideas. It can work with functional boards or circuit boards to implement specific features.

Applications

• This development board applies to a wide range of prototypes implemented with Tuya’s no-code solutions, such as sockets, power strips, switches, and lights.
• Develop with the board to build your IoT projects easily and fast.
• You can use this board for different development purposes.
  • Embedded program development and debugging
  • App development and debugging
  • Creating connected devices that can be controlled with a mobile phone
  • Getting started with IoT development and learning how the Wi-Fi-based control system works

Components

The development board is integrated with Tuya’s proprietary low-power Wi-Fi and Bluetooth LE combo module WBRU. This module consists of a highly integrated wireless chip W701-VA2-CG with built-in Wi-Fi stacks and various library functions. The development board has on-board buttons, LED, GPIOs, and a USB-to-serial chip. For more information, see the WBRU Module Datasheet.

I/O port and pin description

• 1: Micro-USB (CN1): Inputs 5V DC voltage and provides two extended serial ports.

• 2: DIP switch (S1): Flip the toggle to the ON position to complete the circuit. The switch is used to open and close the circuit between the USB-to-serial chip and the chip’s serial port.

• 3: LED indicator (D3): When the 3.3V power is on, the LED is on.

• 4: Button (S2): When the button is pressed, PA12 outputs low. When the button is released, it outputs high.

• 5: LED indicator (D2): When PA18 outputs low, the LED is on.

• 6: Button (RST): When the button is pressed, the module is reset.

  Pin description

  No.	Pin name	Description
  1	NC	Leave it floating.
  2	3.3V	3.3V power pin.
  3	NC	Leave it floating.
  4	NC	Leave it floating.
  5	NC	Leave it floating.
  6	PA18	GPIOA_18 on WBRU, which can be used as PWM output.
  7	PA19	GPIOA_19 on WBRU, which can be used as PWM output.
  8	PA20	GPIOA_20 on WBRU, a GPIO pin.
  9	PA0	GPIOA_0 on WBRU. Pull-up will trigger the testing mode. It is not recommended to add an external pull-up resistor for this pin.
  10	PA10	GPIOA_10 on WBRU, which can be reused as SPI_MISO.
  11	PA7	GPIOA_7 on WBRU, which can be reused as SPI_CS.
  12	5V	5V power pin.
  13	RST	Clock enable (CEN) pin on WBRU. It can output the chip enable and high enable signals.
  14	GND	Ground pin.
  15	NC	Leave it floating.
  16	PA14	GPIOA_14 on WBRU, which can be reused as the UART0_TXD pin for serial communication.
  17	PA13	GPIOA_13 on WBRU, which can be reused as the UART0_RXD pin for serial communication.
  18	RST	Clock enable (CEN) pin on WBRU. It can output the high enable signal.
  19	GND	Ground pin.
  20	PA8	GPIOA_8 on WBRU, which can be reused as SPI_SCK.
  21	PA9	GPIOA_9 on WBRU, which can be reused as SPI_MOSI.
  22	PA15	GPIOA_15 on WBRU, which can be reused as the UART_Log_RXD pin for log printing.
  23	PA16	GPIOA_16 on WBRU, which can be reused as the UART_Log_TXD pin for log printing.
  24	PA2	GPIOA_2 on WBRU, which can be used as PWM output.
  25	PA3	GPIOA_3 on WBRU, which can be used as PWM output.
  26	PA4	GPIOA_4 on WBRU, which can be used as PWM output.
  27	PA11	GPIOA_11 on WBRU, which can be used as PWM output.
  28	PA12	GPIOA_12 on WBRU, which can be used as PWM output.
  29	PA17	GPIOA_17 on WBRU, which can be used as PWM output.
  30	NC	Leave it floating.

Load-carrying capacity

• When micro-USB (CN1) inputs 5V DC voltage, the board can supply power to external components.

  Power pin	Rated voltage/current
  5V	Depends on the input current of the adapter connected to the DC-005 terminal.
  3.3V	3.3V/0.6A

• Characteristics of output voltage

  Output current	0A	0.15A	0.3A	0.45A	0.6A	0.75A
  Output voltage	3.34V	3.36V	3.37V	3.37V	3.38V	3.38V

  We tested the voltage under the condition that there is no output voltage on the micro-USB (CN1) terminal.

Schematic diagram and PCB

• The schematic diagram of the board:

  

• The PCB board:

  

  

How USB-to-serial works

• The board has a built-in USB-to-serial chip. The single-channel USB port can provide two extended serial ports. You can flip the DIP switch (SW1) to enable the 2-channel serial port on the WBRU to connect to the USB-to-serial chip. The following table lists the pin definition of the DIP switch.

  DIP switch No.	1	2	3	4
  WBRU module	UART1_RX	UART1_TX	UART2_RX	UART2_TX
  USB-to-serial chip	USB-TX0	USB-RX0	USB-TX1	USB-RX1

  • Flip the toggle to the ON position to complete the circuit. The switch is used to open and close the circuit between the USB-to-serial chip and the chip’s serial port.
  • When you use the UART pin on the chip for communication with an MCU or GPIO, flip the toggle of the corresponding channel to the OFF position (the side with numbers) to open the circuit between the UART on WBRU and the USB-to-serial chip.

• The COM ports map to the UART pins as follows.

  COM ports on the computer	SERIAL-A(COM23)	SERIAL-B(COM22)
  USB-to-serial chip	USB-UART0	USB-UART1
  WBRU module	UART1	UART2

  The COM port number varies depending on computers so we use SERIAL-A and SERIAL-B to indicate the two COM ports.

Connection for DOWNLOAD mode

• If you use Tuya’s software for firmware flashing and module authorization, flip the toggles of channels 1 and 2 on the DIP switch (SW1) to the ON position to complete the circuit between the UART1 on WBRU and the host.

  
  The development board comes with pre-flashed firmware. In this mode, pre-flashed firmware is run.

• If you use the chip manufacturer’s software for firmware flashing, flip the toggles of channels 3 and 4 on the DIP switch (SW1) to the ON position to complete the circuit between the UART2 on WBRU and the host. Connect PA0 and PA13 to the 3.3V pin.

  
  The chip manufacturer’s software can only be used to flash firmware to the module. You need to use Tuya’s software to authorize the module.
  If you flash the firmware to the module at a specified address, authorizing the module again is not needed.

Connection for viewing logs on the host

Flip the toggles of channel 3 and 4 on the DIP switch (SW1) to the ON position to complete the circuit between the UART2 on WBRU and the host.

Connection for user I/O and host communication

Flip the toggles of channel 1 and 2 on the DIP switch (SW1) to the ON position to complete the circuit between the UART1 on WBRU and the host.

Connection for using both UARTs as GPIOs

Flip the toggles of channel 1 to 4 on the DIP switch (SW1) to the OFF position to open the circuit between the UARTs on WBRU and the USB-to-serial chip.

USB-to-serial chip driver

Download the USB-to-serial chip driver for your operating system.

• For Windows
• For Linux

Things to note

• The board has a built-in power supply port and circuit, so the additional power board is not necessary.
• This board only supports USB port that supplies 5V output.
• If you want to use PA13, PA14, PA15, and PA16 for other circuits, make sure to flip the toggle of the corresponding channel to the OFF position to open the circuit between the UART on WBRU and the USB-to-serial chip.