S100 Slave - WiFi/BT RTL8273BU


The WiFi/BT RTL8273BU is a rhomb module for communications that uses the standard ieee 802.11n and Bluetooth 2.1/3.0/4.0 controller. It combines a WLAN MAC, a 1T1R capable WLAN baseband, and RF in s single chip. The RTL8723BU provides a complete solution for a high‐performance integrated wireless and Bluetooth device. The integration provides better coordination between 802.11 and Bluetooth, and with sophisticated dynamic power control and packet traffic arbitration.

This module can work only as a slave.

The next two figures shows the top and the bottom side of the WiFi/BT RTL8273BU:

WiFi-BT RTL8273BU TOP.jpgWiFi-BT RTL8273BU BOT.jpg


  • Internet of things (IoT).
  • Bluetooth to WiFi/WiFi to Bluetooth bridge.
  • PC network.
  • Mobile.

Module specifications

Key features

The RTL8273BU is a communication rhomb slave module that combines communications features with other devices for a rhomb motherboard using the standard 802.11n/b/g (WiFi) and Bluetooth. It is based on the Chipset RTL8273BU and it contains all the circuitry needed to integrated. It includes a connector for an external antenna.

RTL8273BU uses the USB pins to communicate

The following figure identifies the main Integrated Circuits (IC) onboard.


The next figure shows the Block Diagram for the GPRS SIM800 Module.

WiFi-BT RTL8273BU BlockDiagram.JPG

WiFi & BT (RTL8273BU) Key Features
Easy way to add WiFi and BT to a system with USB interface. Based on Realtek chipset 2.4 GHz
USB 2.0
802.11b/g/n Wireless LAB
Bluetooth 4.0
WiFi RF power: 16dBm@11b, 14dBm@11g, 13dBm@11n
BT RF power: MAX +10 dBm
uMCC antenna connector
Op. Voltage: 1.8 V to 3.3 V (interface), 3.3 V (controller)
Op. Temperature: -40 ºC to +85 ºC



The following table summarizes the GPIOs used on the RTL8273BU. Note that ZZ of them should be configured as interrupt sources.

Rhomb.io pinout Signal (module) Device Interruption
GPIO1 INT_IN WiFi-Module Yes

For more details, look at the module specifications for the Rhomb.io standard.

Serial interfaces

The following table indicates the available serial interfaces on the Rhomb.io standard and which of them are in use. The table also shows the nomenclature used on the Rhomb.io standard and its corresponding on the schematic.

Signal (Rhomb.io) Signal (module) Used by Signal (Rhomb.io) Signal (module) Used by
I2C_SDA Unused SPI_MISO Unused
UART_TXD USB_DATA_N D+ WiFi Controller

The I2C pull-ups resistors should be mounted on the bus, otherwise, the I2C bus will not work. For more details, look at the module specifications for the Rhomb.io standard.


The Secure Digital Input Output (SDIO) interfaces are not used on the S100 Slave - WiFi/BT RTL8273BU.


As per the supply lines used on the board, there is a summary on the next table.

Signal (Rhomb.io) Signal (module) Voltage (V) Used
1V8 150mA 1.8 No
2V8 150mA 2.8 No
VCH 5 No
VSYS 3 - 5.5 No
3V3 VCC33 3.3 Yes
VIO-IN VIO-IN Master Yes

For more details, look at the module specifications for the Rhomb.io standard.

Other signals

The pin int0 is used as an interrupt input for the WiFi/BT RTL8273BU module.


Click the image below to download the schematic files.


  • Precaution against Electrostatic Discharge. When handling Rhomb.io products, ensure that the environment is protected against static electricity. Follow the next recommendations:
  1. The users should wear anti-static clothing and use earth band when manipulating the device.
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  3. Equipment and work table must be earthed.
  4. Ionizer is recommended to remove electron charge.
  • Contamination. Be sure to use semiconductor products in the environment that may not be exposed to dust or dirt adhesion.
  • Temperature/Humidity. Semiconductor devices are sensitive to environment temperature and humidity. High temperature or humidity may deteriorate semiconductor devices characteristics. Therefore avoid storage or usage in such conditions.
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  • EMS (Electromagnetic Susceptibility). Note that semiconductor devices characteristics may be affected by strong electromagnetic waves or magnetic field during operation.


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