feat: ESP32 CSI transmitter MAC address filtering

[ruvnet]

Summary

• Add MAC address filter to ESP32 CSI collector to prevent signal mixing in multi-AP environments
• Filter by transmitter MAC in the wifi_csi_callback — non-matching frames are silently dropped
• Configurable via Kconfig (CSI_FILTER_MAC) and NVS (filter_mac blob) for runtime flexibility
• Log transmitter MAC in periodic CSI callback debug output for diagnostics
• Default behavior unchanged: no filter = accept all transmitters (backward compatible)

Configuration

Compile-time (menuconfig):

CSI Node Configuration → CSI source MAC filter = "AA:BB:CC:DD:EE:FF"

Runtime (NVS, no reflash needed):

# Via provisioning script or esptool
nvs_set blob csi_cfg filter_mac "AA:BB:CC:DD:EE:FF"

Files Changed

• firmware/esp32-csi-node/main/csi_collector.c — MAC filter logic in CSI callback
• firmware/esp32-csi-node/main/csi_collector.h — csi_collector_set_filter_mac() API
• firmware/esp32-csi-node/main/nvs_config.c — Parse Kconfig MAC string + NVS blob override
• firmware/esp32-csi-node/main/nvs_config.h — filter_mac + filter_mac_enabled fields
• firmware/esp32-csi-node/main/Kconfig.projbuild — CSI_FILTER_MAC option
• firmware/esp32-csi-node/main/main.c — Apply filter from config at boot

Test plan

• Flash to ESP32-S3, verify default mode (no filter) works as before
• Set CSI_FILTER_MAC to AP MAC, verify only that AP's CSI is processed
• Set CSI_FILTER_MAC to wrong MAC, verify all CSI is dropped (s_filtered increments)
• Test NVS override: flash without Kconfig MAC, set via NVS, reboot, verify filter active
• Verify log output shows transmitter MAC in periodic CSI callback messages

Fixes #98

🤖 Generated with claude-flow

[ruvnet]

Firmware Build & Flash Verification ✅

Build method: Docker (espressif/idf:v5.2)
Target: ESP32-S3 (QFN56, rev v0.2)
MAC: 3c:0f:02:ec:c2:28
Port: COM7

Build

• 961/961 compilation steps passed
• Binary: esp32-csi-node.bin (788,832 bytes, 25% flash free)
• Build command: docker run --rm -v ... espressif/idf:v5.2 bash -c "idf.py set-target esp32s3 && idf.py build"

Flash

• All 3 partitions written and hash-verified:
  • bootloader.bin (21,056 bytes) at 0x0
  • partition-table.bin (3,072 bytes) at 0x8000
  • esp32-csi-node.bin (788,832 bytes) at 0x10000

Boot Verification

• ESP-IDF v5.2, compile time Mar 2 2026
• NVS config module loads correctly (falls back to compiled defaults)
• MAC filter code compiled in (activated via NVS filter_mac blob or Kconfig CONFIG_CSI_FILTER_MAC)
• WiFi STA mode initializes, CSI collection ready
• Node ID: 1 (default)