Wireless Tag WT99P461-S1: $21 ESP32-P4X dev board adds Ethernet, RS-485, CAN bus, MIPI CSI/DSI

Wireless Tag has released the WT99P461-S1, a full-featured development board built around the ESP32-P4X (v3.2) dual-core RISC-V microcontroller and ESP32-C61 wireless companion chip. The board expands on the earlier ESP32P4C61-TINY by adding Fast Ethernet, RS-485, CAN bus, on-board microphone, and speaker connector while retaining MIPI DSI/CSI interfaces, microSD slot, and USB OTG ports. It targets industrial HMI, gateway, and control applications with a 120 x 90 mm form factor and 50-pin GPIO expansion header.

The board ships with pre-installed firmware running a smartphone-style interface via the ESP-Brookesia framework, including AI vision demos, 7-inch touchscreen support, MP3 audio, MJPEG video playback, and SC2336 camera support. Wireless Tag confirmed the module uses the newer ESP32-P4 v3.2 silicon rather than the original v1.3, featuring 360/400 MHz dual-core RISC-V with AI extensions, a 40 MHz low-power core, 2D PPA graphics accelerator, H.264/JPEG codec, and 32MB PSRAM. The company sells the board directly at $21 bare or $42.50 with a 7-inch display kit.

ESP32-P4X silicon and board-level I/O architecture

• ESP32-P4X v3.2 compute complex: Dual-core RISC-V application processor at 360/400 MHz with AI instruction extensions and single-precision FPU, paired with a single-core 40 MHz low-power RISC-V core for always-on tasks.
• Memory hierarchy: 768 KB HP L2MEM, 32 KB LP SRAM, 8 KB TCM, plus 32MB external PSRAM and 16MB NOR flash on the WT01P461-S1 module; 128 KB HP ROM and 16 KB LP ROM for boot and low-level code.
• Multimedia accelerators: 2D Pixel Processing Accelerator (PPA) for graphics composition, plus VPU with H.264 and JPEG codec support; note that current firmware only enables MJPEG playback, not H.264 decode.
• Industrial and wired connectivity: 10/100 Mbps Fast Ethernet RJ45, RS-485 terminal block, CAN bus terminal block, and USB 2.0 OTG via both Type-C (Full-Speed) and Type-A (High-Speed) ports.
• Display, camera, and audio interfaces: 30-pin MIPI DSI with 6-pin capacitive touch, 15-pin MIPI CSI for camera, on-board microphone, and 2-pin speaker connector supporting up to 4Ω 3W speakers; wireless via ESP32-C61 providing WiFi 6 and Bluetooth 5.4 with IPEX antenna.

Why it matters

The WT99P461-S1 fills a gap between bare ESP32 modules and expensive industrial SBCs by packaging the newer ESP32-P4X v3.2 silicon with fieldbus interfaces and display support at a sub-$25 price point, making it competitive for Linux-adjacent embedded development where real-time control and HMI convergence matter. However, the lack of published schematics, gerbers, or firmware source on Wireless Tag's GitHub raises open-hardware completeness questions that FOSSWire will monitor, since the ESP-IDF and ESP-Brookesia frameworks are open but board-specific enablement code remains unverified.