The RDA5981, an ESP8266 Competitor?

Alasdair Allan
3 min readJan 17, 2018

Over the last few years, the ESP8266 has become the “third community” of the maker electronics world, right alongside the Arduino and the Raspberry Pi.

Initially marketed as a Serial-to-WiFi adaptor, it came with firmware supporting a simple AT command set to configure and control the wireless module. What most people initially missed was that it was also fully programmable, this was a general use microcontroller, with Wi-Fi and — albeit somewhat limited — GPIO, all for a couple of dollars. This probably had something to do with the fact that, at least at first, all the documentation was in Chinese.

However, it didn’t take all that long for interesting things to start happening. The ESP8266 became successful due to the community that rapidly grew around it. This community coalesced not because of the features the board offered — there have been other small form factor wireless boards — but because of one feature the other boards didn’t offer, the price point.

Since the ESP8266 arrived there have been a number of possible competitors, like the RTL8710. But none of them have managed to dislodge the ESP8266 because, like the the Arduino and the Raspberry Pi, the important thing that makes the ESP8266 a success is the community.

Now there’s another competitor, the RDA Micro RDA5981.

An RDA5981 development board. (📷: RDA)

The RDA5981 isn’t actually a new chip, it was announced back at the tail end of 2016 during IC China, but boards and modules aimed at makers have only now started to appear on AliExpress and Taobao.

The chip has been designed for smart home and audio applications, and it is used in devices running Baidu DuerOS, with RDA providing support for FreeRTOS and mbed OS for the chip. You can find the datasheets for the chip on GitHub

The RDA5981 is built around an Arm Cortex- M4 core running at 160MHz. It has up to 192KB of SRAM, and up to 8MB of Flash. It has a built-in USB 2.0 host interface—something that the ESP8266 lacks—an SDMMC interface, and support for Bluetooth. It has 2×10bit ADC, 2×UART, and 14×GPIO pins with support for SIDO, I2C, I2S, PWM and SPI. It has a onboard hardware cryptographic accelerator supporting AES/RSA, and True Random Number Generator (TRNG), and CRC accelerator. The onboard TCP stack is advertised as ‘secure’ although it’s unclear whether that means SSL, or TLS, support.

The RDA chip is also one of the few competitors to the ESP8266 to appear which is actually price-competitive to the Espressif chip, with Electrodragon offering a WiFi module based on RDA5981A for $1.92 a piece.

The Electrodragon RDA5981X1 module. (📷: Electrodragon)

While the maker market is very price sensitive, it’s also very reliant on community support. The software toolchains built around Espressif chip, just like those around the Arduino and the Raspberry Pi, means that those platforms will tend to persist—unless there are huge advantages to building on a newer platform with less community support—and even then if the Espressif chip is ‘good enough’ then the advantages of community support will tend to outweigh any performance or features the new platforms might offer. So despite the new competitor, I don’t actually think it’s likely that the ESP8266 will be unseated any time soon.