How to Deploy 65 WASM Edge Modules on ESP32 Using WASM3 Runtime with RuView

Deploy 65 WebAssembly edge modules to an ESP32-S3 by compiling them to wasm32-unknown-unknown, flashing the WASM3-enabled firmware, and uploading binaries via the HTTP API on port 8032.

RuView provides a Tier-3 programmable-sensing layer that runs hot-loadable WASM edge modules directly on ESP32-S3 microcontrollers using the lightweight WASM3 interpreter. This architecture allows you to deploy up to 65 distinct edge modules—such as the reference "6S" collection including sig_flash_attention and spt_micro_hnsw—for sub-5 millisecond on-device inference without rebooting the hardware.

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Build WASM Edge Modules for ESP32 Deployment

Install the WASM32 Target

Before compiling the RuView edge modules, add the WebAssembly target to your Rust toolchain:

rustup target add wasm32-unknown-unknown

Compile the Edge Module Collection

RuView organizes its 65 WASM modules within the wifi-densepose-wasm-edge crate. Build the entire collection or specific subsets using Cargo:

cargo build \
    --release \
    --package wifi-densepose-wasm-edge \
    --target wasm32-unknown-unknown

The compiler outputs .wasm binaries to:

target/wasm32-unknown-unknown/release/

Key modules in the 6S reference set include:

• sig_flash_attention.wasm – Budget-constrained attention mechanism (≤ 5 ms) defined in src/sig_flash_attention.rs
• sig_coherence_gate.wasm – Lightweight coherence gate (≤ 2 ms) from src/sig_coherence_gate.rs
• spt_micro_hnsw.wasm – On-device approximate nearest neighbor search in src/spt_micro_hnsw.rs
• spt_spiking_tracker.wasm – Bio-inspired tracking system in src/spt_spiking_tracker.rs
• tmp_pattern_sequence.wasm – Daily routine pattern detector in src/tmp_pattern_sequence.rs
• tmp_goap_autonomy.wasm – GOAP planner for autonomous sensing in src/tmp_goap_autonomy.rs

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Flash ESP32 Firmware with WASM3 Runtime

Enable WASM Support in ESP-IDF

The RuView firmware located in firmware/esp32-csi-node requires the WASM3 component. Enable it via menuconfig:

cd firmware/esp32-csi-node

idf.py menuconfig

# Navigate to: Component config → WASM3 → Enable (CONFIG_WASM_ENABLE=y)

The WASM3 interpreter is fetched and compiled via components/wasm3/CMakeLists.txt, which pulls the upstream source and links it into the ESP32 image.

Build and Flash the Firmware

Compile the firmware and flash it to the ESP32-S3:

idf.py build flash monitor

Critical runtime components include:

• main/wasm_runtime.c – Initializes the WASM3 environment, allocates 160 KB PSRAM arenas per module slot, and dispatches process_frame calls at approximately 20 Hz
• main/wasm_upload.c – Implements the HTTP REST API on port 8032 for module management

After flashing, the device listens for WASM uploads on TCP port 8032.

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Deploy WASM Modules to the ESP32 Edge

Upload Binaries via HTTP API

RuView exposes a lightweight HTTP API for hot-loading modules. You can deploy using the provided Python helper or manual curl commands.

Using the Python deployment script:

python scripts/esp32_wasm_test.py \
    --port /dev/ttyUSB0 \
    --modules \
        target/wasm32-unknown-unknown/release/sig_flash_attention.wasm \
        target/wasm32-unknown-unknown/release/sig_coherence_gate.wasm \
        target/wasm32-unknown-unknown/release/spt_micro_hnsw.wasm \
        target/wasm32-unknown-unknown/release/spt_spiking_tracker.wasm \
        target/wasm32-unknown-unknown/release/tmp_pattern_sequence.wasm \
        target/wasm32-unknown-unknown/release/tmp_goap_autonomy.wasm

Manual upload with curl:

ESP_IP="192.168.1.42"
ESP_PORT="8032"

for module in sig_flash_attention sig_coherence_gate spt_micro_hnsw \
              spt_spiking_tracker tmp_pattern_sequence tmp_goap_autonomy; do
    curl -X POST "http://${ESP_IP}:${ESP_PORT}/wasm/upload?name=${module}" \
         -H "Content-Type: application/octet-stream" \
         --data-binary @target/wasm32-unknown-unknown/release/${module}.wasm
done

Start and Manage Modules

After uploading, activate individual modules using the start endpoint:

# Start a specific module

curl -X POST "http://${ESP_IP}:${ESP_PORT}/wasm/start?name=sig_flash_attention"

# Verify running modules

curl http://${ESP_IP}:${ESP_PORT}/wasm/list

The list endpoint returns JSON metadata:

{
  "modules": [
    {"name": "sig_flash_attention", "size": 12345, "status": "running"},
    {"name": "spt_micro_hnsw", "size": 9876, "status": "running"}
  ]
}

To stop or remove modules:

# Stop a module

curl -X POST "http://${ESP_IP}:${ESP_PORT}/wasm/stop?name=sig_flash_attention"

# Delete a module

curl -X POST "http://${ESP_IP}:${ESP_PORT}/wasm/delete?name=sig_flash_attention"

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Runtime Architecture and Memory Constraints

RuView’s WASM3 integration enforces strict resource budgets suitable for ESP32-S3 constraints. Each deployed module operates within a 160 KB PSRAM arena allocated by wasm_runtime.c, ensuring isolation between the 65 potential edge modules.

The runtime invokes each module’s process_frame function at the DSP tick rate (approximately 20 Hz). Latency annotations in the source code—such as "Budget: S (< 5 ms)" in sig_flash_attention.rs—guarantee that modules complete inference within their allocated time slices. The WASM3 interpreter’s Tier-3 classification indicates these are hot-loadable, sandboxed algorithms that execute directly on the edge device without cloud dependency.

Host API functions exposed to WASM modules include csi_get_frame for accessing pre-processed CSI data and csi_emit_event for publishing results back to the RuView pipeline, as implemented in the runtime glue layer.

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Summary

• RuView enables deployment of 65 WASM edge modules on ESP32-S3 microcontrollers using the WASM3 interpreter for sub-5 ms on-device inference.
• Build modules by compiling the wifi-densepose-wasm-edge crate to wasm32-unknown-unknown and locating outputs in target/wasm32-unknown-unknown/release/.
• Flash firmware from firmware/esp32-csi-node with CONFIG_WASM_ENABLE=y to embed the WASM3 runtime and HTTP upload API on port 8032.
• Deploy binaries using scripts/esp32_wasm_test.py or direct curl POST requests to /wasm/upload, then activate via /wasm/start.
• Each module runs in an isolated 160 KB PSRAM arena with guaranteed latency budgets, invoked at 20 Hz through the process_frame host API.

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Frequently Asked Questions

How many WASM modules can run simultaneously on ESP32-S3?

RuView supports up to 65 distinct WASM edge modules in the collection, with the runtime capable of loading multiple modules simultaneously depending on available PSRAM. Each active module consumes a 160 KB PSRAM arena allocated by wasm_runtime.c, so practical limits depend on your ESP32-S3’s total PSRAM capacity and the specific subset of modules deployed.

What is the maximum binary size for each WASM edge module?

While the RuView architecture does not enforce a hardcoded binary size limit, modules must fit within the 160 KB PSRAM arena allocated per slot at runtime, as defined in firmware/esp32-csi-node/main/wasm_runtime.c. Additionally, modules must adhere to their annotated latency budgets—typically sub-5 ms for standard modules and sub-2 ms for lightweight gates—to maintain the 20 Hz DSP tick rate.

Can I hot-swap WASM modules without rebooting the ESP32?

Yes. The HTTP API implemented in firmware/esp32-csi-node/main/wasm_upload.c supports hot-loading via the /wasm/upload, /wasm/start, /wasm/stop, and /wasm/delete endpoints. You can upload new binaries, start additional modules, or replace running instances dynamically without reflashing the firmware or power-cycling the device, enabling true Tier-3 programmable sensing at the edge.

Which Rust target is required for RuView edge modules?

All RuView edge modules must compile to the wasm32-unknown-unknown target. This target produces bare-metal WebAssembly binaries without system dependencies, suitable for the WASM3 interpreter running on ESP32-S3. Add the target via rustup target add wasm32-unknown-unknown and build using cargo build --release --target wasm32-unknown-unknown as specified in docs/build-guide.md.

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