$6 Rtlduino RTL8720DN dual-band WiFi IoT board features 2.4/5GHz Wireless MCU

There are plenty of WiFi modules for the IoT market, but those usually work at 2.4 GHz only. This may be an issue in areas where the 2.4 GHz spectrum is overcrowded. But two years ago, we were pleased to see the Ameba Z2  board offering dual-band (2.4GHz and 5Ghz) WiFi thanks to Realtek RTL8720CM wireless MCU, and last year, we discovered B&T BW16 dual-band IoT module based on RTL8720DN sold for under $4 before shipping.

If you like the cheap price of the module, but do not feel like creating your own baseboard, or soldering wires to the module, you’ll be glad to know Rtlduino RTL8720DN board offers an easy way to evaluate RTL8720DN dual-band WiFi (and Bluetooth LE 5.0) microcontroller as it is fitted with a B&T BW16 module and comes in a form factor similar to NodeMCU ESP8266 board.

Rtlduino RTL8720DN board

Specifications:

  • B&T BW16 wireless module
    • Wireless SoC – Realtek RTL8720DN MCU with KM4 Arm Cortex-M4 core @ 200 MHz and KM0 Arm Cortex-M0 core @ 20 MHz
    • Connectivity
      • 802.11 a/b/g/n WiFi 4
        • Frequency Range – 2.412-2.484GHz & 5.180-5.825GHz
        • Data Rates
          • 802.11a: 6,9,12,18,24,36,48,54Mbps
          • 802.11b: 1,2,5.5,11Mbps
          • 802.11g: 6,9,12,18,24,36,48,54Mbps
          • 802.11n: MCS0–MCS7 @ HT20/HT40 2.4GHz and 5GHz bands
        • AP, Station, AP/Client supported
      • Bluetooth 5.0 LE
        • Receiver Sensitivity: -92 dBm
        • Transmit Power: 7 dBm
      • Antenna – IPEX connector or PCB Antenna (CNXSoft: the latter is used on Rtlduino board)
    • I/O – 16x castellated holes with GPIO, 2x UART (AT commands + serial), ADC, I2C, SPI, 4x PWM, 3.3V, GND
    • Supply Voltage – 3.3 ±5% V
    • Dimensions – 24 x 16 x 3 mm
    • Certifications – FCC, CE, SRRC, RoHS
  • USB – 1x Micro USB port for power and programming
  • Expansion – 2x 15-pin headers with BW16 I/Os
  • Misc – Reset and Burn buttons, RGB LED
  • Power Supply – 5V via Micro USB port
  • Dimensions – 49 x 26mm (TBC, I just used NodeMCU dimensions)
Pinout diagram

You may wonder why “RTL-00” is shown in the pinout diagram above, and that’s most likely because it’s not the only Rtlduino board around, as we previously wrote about RTLduino RTL8710 board based on RTL-00 WiFi-only module. The new board appears to rely on the same baseboard and is just fitted with a BW16 dual-band WiFi IoT module instead.

Software Support – GCC Toolchain & Arduino

As I understand it, RTL8720DN is part of the Realtek Ameba D family, and you’ll find the SDK and a getting started guide explain how to get started (GCC toolchain, build code, flash the binary) in Windows or Linux with the board. One person nicknamed a2302004040 also explains how to use the board with the Arduino IDE in Arduino China forum, but if you prefer English check out ambd_arduino repo on Github. The info on the Arduino forum is however more detailed, and there are code samples for blinking an LED and connect to WiFi.

Rtlduino RTL8720DN board can be purchased on Aliexpress for $6 plus shipping (That’s the fourth choice in the list).

Thanks to Ophir for the tip.

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