The TXW8301 IEEE 802.11ah Halow SoC from Chinese manufacturer, TaiXin Semiconductor is unique from other Halow semiconductor vendors in that it has a RMII interface for connection to an external Ethernet PHY. This allows the SoC to act as a cost-effective Long Range Halow Wireless Ethernet Bridge. As a result, the TXW8301 is commonly found in many Wireless Network Bridges (WNB) found on platforms like AliExpress and Amazon.

The WNB is typically sold as a pair of two identical units. One is configured in Access Point (AP) mode, and the other in Station (STA). As most of the TXW8301 have been deployed this way, the units never need to interoperate with other Halow Wi-Fi Alliance compatible devices.

TXW8301 Specifications

The TXW8301 has the following specifications

• IEEE 802.11ah WiFi Sub GHz radio supporting 1/2/4/8 MHz channels
• 32-bit RISC CPU 192MHz
• 704KB SRAM
• USB 2.0 Full Speed Host/Device
• SDIO 2.0/SPI, clock up to 50MHz
• 2x UART
• 1x I2C
• RMII MAC up to 100Mbps

Like the Newracom parts, the on-board CPU can run user applications making it a single SoC for sensor (or Ethernet Bridge) applications. A SDK is available to developers.

Most of the documentation can be found directly from TaiXin in good polished English.

The TXW8301 has FCC, CE, MIC (Japan) and to my delight, even RCM regulatory approval here in Australia (and New Zealand.)

The big differentiator from other Halow Chip offerings is the Ethernet RMII interface. With an external supported PHY such as the IP101GR or RT8201, you can build a cost effective wireless Ethernet bridge without the requirements for a full embedded Linux host.

The RISC CPU (ck803) is a C-SKY T-Head CPU. C-Sky Microsystems was acquired by T-Head Semiconductor Co., Ltd, a subsidiary of Alibaba Group. The CDK (CSKY Development Kit) is available with most functions in English.

The TXW8301 (TXW4002a) doesn’t appear to have a UART based ROM boot-loader. Programming is performed using a two wire CKLink-Lite debugging tool (available from Aliexpress). If you don’t have the debugger, proceed with caution when updating the firmware.

Modules

TaiXin (Zhuhai Huge-ic) also make their own TXW8301 based modules. They have a base part number of TX-AH-R900 with various options as per below:

Additionally, a module for the 860MHz frequency range (Europe) is available.

Lilygo T-Halow RJ45

I purchased a single Lilygo T-Halow RJ45 to evaluate the TXW8301 Chipset. It seemed to be a safer bet than buying a pair of Wireless Net Bridges. Lilygo has documentation, including schematics on their Github product page.

The product – incorporating a RJ45 PCB mount plug is interesting. The device is designed to plug directly into your Ethernet router/switch or host e.g. PC, Raspberry PI etc and provide a driverless network connection. I’m not sure if I’m sold on the design – maybe a standard RJ45 female socket would have been better.

The USB port is intended to power the device, and allows for configuration via a built in USB to Serial Converter (CH340). This was a bonus, as prior to purchase I had studied the schematics provided (V0.1) and had expected to configure it via the 3.3V UART pins. The CH340 bridge was not included at that stage.

The listing, shown below, claimed “Wi-Fi CERTIFIED Halow for IoT Halow”. My expectation was to simply connect it to my Morse-Micro based Access Point.

The T-Halow-RJ45 has a module with the label pictured below – Model: T-Halow and a FCC-ID of 2AXPI-R900. According to the FCC report, it would appear the module is a TX-AH-R900 re-badged and manufactured by Zhuhai Huge-ic Co.,Ltd a company that shares the same address than TaiXin Semiconductor.

The variant of the module can be determined by the labeling in the left-bottom and right-bottom corners. I had ordered the 900MHz version. The module fitted is ‘P9’ ‘NR’ indicating it is a TX-AH-R900PNR fitted with a RX Saw Filter. The 860MHz version should have 86 in the left-bottom corner.

The product shipped from Lilygo with version 1.6.4.3-38054 of TaiXin’s WNB firmware. In STA mode, it could see the SSID of my AP, but refused to connect – even with no encryption selected (open). In AP mode, none of my Morse-Micro or Newracom Halow stations could see it.

According to the Wi-Fi Alliance, the TXW8301 had undergone certification in April 2024 (Certification ID: WFA130865). However, the report states the role tested was station and the “Wi-Fi components operating system” was Linux (using v2.4 firmware). Most likely, the Linux Soft-MAC (or maybe Full-Mac) was tested (but not the embedded SDK’s FMAC) and possibly only as a station. Other observations from the report is only 1MHz and 2MHz channel bandwidths were tested.

The challenge of interoperability with newer, less mature technology and with the rapid pace of development, is it is also possible version 2.4 tested worked, and subsequent updates broke it.

I have made the assumption the Silicon and PHY is good, but maybe the embedded MAC layer is not as compatible outside of the TaiXin ecosystem. A further investigation found the latest SDK version at the time of writing is 2.4.1-43933 – a version closer to the v2.4 named in the certification report.

The SDK V2.4 includes the TXW8301_WNB-v2.4.1.3-43933 Wireless Network Bridge source code.

There are some unofficial comments floating around the web that WNB 1.6.x firmware only supported Taixin’s proprietary NetBridge pairing and that WNB 2.x provided both WNB and a standard Halow option.

According to the TXSDK WiFi Development Guide V1.0, the “The SDK’s WiFi protocol stack supports both standard WiFi protocols and TaiXin’s proprietary WiFi protocol.”

In firmware versions 2.x, the Wi-Fi modes were expanded to include ap, sta, wnbsta, wnbap, apsta, wnbapsta, wnbapwnbsta and apwnbap. The commands without the wnb prefix were standard Halow and the wnb prefixed commands were TaiXin’s proprietary NetBridge modes, backwards compatible with WNB 1.6 firmware.

Firmware Update

The firmware can be updated on the TXW8301 based device using the UART command AT+FWUPG and XMODEM protocol. Luckily, as someone who grew up using the BBS (bulletin board system) era, I knew what XMODEM was. I used TeraTerm to upload the new firmware.

After the firmware update, there was a little panic that some of the AT commands were not working. The wnb 2.x firmware has a revised AT command set. This is a good summary – 2.x Firmware AT Commands Reference.

After a little while re-familiarising myself with the new command set, I wasn’t getting the results I expected with AT+WIFIMODE=STA and AT+WIFIMODE=AP. It was time for Wireshark.

Wireshark

Wireshark is a open source protocol analyzer that can be used to observe and decode packets including 802.11ah Halow frames and beacons.

I first placed my T-Halow-RJ45 into ‘standard’ AP mode (AT+WIFIMODE=ap). Straight away I could see frames that Wireshark indicated was a malformed packet. Closer investigation showed they were not a S1G Beacon (Type/Subtype 0x0031), but rather an Action (Type 0x000D) with a category of 221 (if encoded correctly, and wireshark is not erroneously decoding an entirely proprietary frame – which I think is the case). They were also sent every 2 seconds, not the expected 102.4 milliseconds.

When I tried to put the TXW8301 into the proprietary WNB mode (AT+WIFIMODE=wnbap), I got the response "mode=wnbap is not supported!".

I then configured the T-Halow-RJ45 into STA mode and tried to get it to connect to my Morse Micro AP. From the T-Halow-RJ45 UART console, it would report :

It could find my Morse Micro AP (0C:BF:74:2C:A3:2C) and try to connect – but would respond with "ieee80211_sta_assoc_timeout:53::connect to ap 0c:bf:74:2c:a3:2c timeout, disable it!"

Wireshark showed it was sending a Probe Request, but never getting back a Probe Response (0x0005) from the Access Point. I’m no expert in this area and I believe the specification documents are closed to paid members. This could be a problem with the Morse Micro AP or could be a problem with the TXW8301 asking for the wrong parameters in the Probe Request.

Unless there are other commands or settings to make the TXW8301 more Halow standard, I would be led to believe the WNB-v2.4.1.3-42933 firmware is not yet compatible with other Halow software stacks.

If you are planning on purchasing a TXW8301 based Halow device such as the LilyGO T-Halow boards, make sure you buy two so you have a compatible device to communicate with.

Feel free to share your experience or findings below. Have you managed to get a TXW8301 based device connected to a Morse Micro or Newracom Access Point?