RDA Microelectronics processors are found in a few cheap smart and not-so-smart phones, as well as the even cheaper Orange Pi i96 board. But the company does not only design cellular chips, but their portfolio also includes solutions for the Internet of Things and TV & radio tuners.

RDA5981 is a WiFi IoT chip specifically designed for smart home & audio application, such as smart speakers, and it’s found in devices running Baidu DuerOS, the Chinese equivalent of Amazon Alexa or Google Assistant. The company explains it can be widely used in televisions, set-top boxes, smart appliances, wireless monitors, and other products.

RDA5981 A/B/C processor specifications:

CPU – Arm Cortex-M4 @ up to 160 MHz with integrated MPU and mbed uvisor

System Memory – Up to 448 KB SRAM for network stack and application, external PSRAM interface

Storage – Up to 32Mbit SPI flash

Connectivity WiFi 2.4 Ghz 802.11b/g/n WiFi up to 150 Mbps with 20/40 MHz bandwidth WPA, WPA2, WEP, TKIP,CCMP security STA, softAP, P2P, STA+softAp, STA+P2P modes A-MPDU, A-MSDU, HT-BA TCP/IP stack with SSL (TLS?)

Host Interfaces – SPI / UART (AT command set) / USB2.0

Peripherals – GPIO, 2x UART, 2x I2S, 1x I2C, 8x PWM, 4x SPI, 1x SDMMC, 1x USB2, 2x ADC

Security – Hardware crypto accelerator AES/RSA, true random number generator (TRNG), and CRC accelerator

Misc – Watchdog, 16×16 bits eFuse configuration

Package – 5×5mm2 QFN package, 0.4mm pitch QFN-40

The company provides support for FreeRTOS and mbedOS5.1 for the chip. You could get a very basic datasheet from the company’s product page, but if you don’t want to leave your contact details, there’s even more information on Electrodragon Wiki.

The features looks interesting and could become a competitor to Realtek RTL8710AF or even Espressif ESP8266, especially Electrodragon sells their RDA5981X1 WiFi module based on RDA5981A for just $1.92 plus shipping.

Specifications for the module:

SoC – RDA5981A with 8Mbit internal flash, 288+160 KB RAM

24 castellated pin exposing Up to 16 free GPIOs 2x UART up to 4Mbit, 3x ADC, 1x USB, 1x I2C, I2S in, I2S out, 1x SPI, up to 4x PWM, etc… (Pins are multiplex with up to 6 different function per pin) VCC (3.0 to 3.5V), GND Reset

Dimensions – 17.60 x 15.50 mm

The module also comes with a red breakout board (with 2.54mm pitch) included in the price. The company says RDA5981A IC itself sells for around $1 with price obviously depending on quantity.They also mention the SoC still have bugs without expanding. The board can be programming with AT commands or using mBed as explained in the Wiki linked above.

There’s also an RDA5981 board with Arduino header, which I could only find on Taobao for under $50. Somebody also setup a new Github account with more information, and beside the RDA5981A/B/C models listed in the datasheet, there seems to be an RDA5981AM chip as well. All RDA5981 variants are shown to be suitable for smart home, but RDA5981C can also be used for smart speakers and WiFi toys, maybe because it comes with 32 Mbit SPI flash? We’ll have to see how things evolve, and whether the solution will gain traction.

Via Olimex