a87151cc9c
Replace all CONFIG_CSI_HOSTNAME usage with runtime s_hostname variable. Load from NVS on boot (falls back to Kconfig default). HOSTNAME <name> sets hostname, persists to NVS, updates mDNS live. HOSTNAME (no arg) queries current value. One firmware binary now works for all devices.
ESP32 Firmware Hacking
Resources for customizing ESP32 CSI firmware.
Directory Structure
esp32-hacking/
├── get-started/ # Basic CSI examples (CURRENTLY USED)
│ ├── csi_recv_router/ # <-- OUR FIRMWARE (modified for UDP)
│ ├── csi_recv/ # Basic receiver (serial output)
│ ├── csi_send/ # CSI transmitter
│ └── tools/ # Python CSI parsing tools
├── esp-radar/ # Advanced presence detection
│ ├── console_test/ # Interactive CSI testing console
│ └── connect_rainmaker/ # IoT cloud integration
├── esp-crab/ # Dual-antenna experiments
│ ├── master_recv/ # Master receiver
│ ├── slave_recv/ # Slave receiver
│ └── slave_send/ # Slave transmitter
└── README.md # This file
Current Firmware
Source: get-started/csi_recv_router/
Origin: Espressif esp-csi example, modified for UDP output
Deployed on: 3x ESP32-DevKitC V1
What It Does
- Connects to WiFi router as station
- Pings gateway at 100 Hz to generate CSI frames
- On each CSI callback, formats data as text
- Sends via UDP to Pi (port 5500)
Key Settings (sdkconfig.defaults)
| Setting | Value | Purpose |
|---|---|---|
CONFIG_ESP32_WIFI_CSI_ENABLED |
y | Enable CSI extraction |
CONFIG_ESP32_WIFI_AMPDU_TX_ENABLED |
(empty) | Disable TX aggregation |
CONFIG_ESP32_WIFI_DYNAMIC_RX_BUFFER_NUM |
128 | Large RX buffer |
CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ |
240 | Max CPU speed |
CONFIG_FREERTOS_HZ |
1000 | 1ms tick resolution |
CONFIG_ESP_TASK_WDT_TIMEOUT_S |
30 | Watchdog timeout |
CONFIG_COMPILER_OPTIMIZATION_PERF |
y | Performance optimization |
Custom Config (Kconfig.projbuild)
| Config | Description |
|---|---|
CONFIG_CSI_UDP_TARGET_IP |
Pi's IP address (192.168.129.11) |
CONFIG_CSI_UDP_TARGET_PORT |
UDP port (5500) |
CSI Data Format
CSI_DATA,<seq>,<mac>,<rssi>,<rate>,<sig_mode>,<mcs>,<cwb>,<smoothing>,
<not_sounding>,<aggregation>,<stbc>,<fec_coding>,<sgi>,<noise_floor>,
<ampdu_cnt>,<channel>,<secondary_channel>,<timestamp>,<ant>,<sig_len>,
<rx_state>,<len>,<first_word_invalid>,"[csi_values]"
Build & Flash
source ~/esp/esp-idf/export.sh
cd ~/esp/esp-csi/examples/get-started/csi_recv_router
idf.py menuconfig # Change WiFi SSID/password, UDP target IP
idf.py build
idf.py -p /dev/ttyUSB0 flash
idf.py -p /dev/ttyUSB0 monitor # View serial output
Firmware Modification Ideas
1. Remote Commands (UDP bidirectional)
Add a UDP listener on the ESP32 to receive commands from the Pi.
// Commands to implement:
// REBOOT - restart ESP32
// IDENTIFY - blink onboard LED for 5 seconds
// STATUS - reply with uptime, free heap, RSSI, chip temp
// RATE <n> - change ping/CSI rate (packets per second)
// OTA <url> - trigger OTA firmware update
Complexity: Low Impact: High - enables remote management without USB
2. Adaptive Sampling Rate
Reduce packet rate when no presence detected, increase on motion.
// Idle: 10 pkt/s (saves power, bandwidth)
// Active: 100 pkt/s (full resolution)
// Trigger: wander threshold on-device
Complexity: Medium (needs on-device wander calculation) Impact: Medium - reduces Pi CPU load by ~90% when idle
3. On-Device CSI Processing
Pre-compute amplitude on ESP32, send only metrics.
// Instead of raw CSI (128 int16 values per packet = 256 bytes):
// Send: "METRICS,<seq>,<rssi>,<wander>,<jitter>,<amplitude_mean>"
// ~50 bytes per packet instead of ~500
Complexity: Medium Impact: High - 80% bandwidth reduction
4. LED Status Indicator
Use onboard LED (GPIO2 on most DevKitC) for status.
// Off: No WiFi connection
// Slow blink: Connected, no CSI activity
// Fast blink: Sending CSI data
// Solid: Identify mode (triggered by command)
Complexity: Low Impact: Low - quality of life
5. BLE Scanning
ESP32 has Bluetooth. Scan for nearby BLE devices.
// Periodically scan for BLE advertisements
// Report: MAC, RSSI, device name
// Use for: phone/wearable proximity detection
// Complements CSI: confirms person is home (phone detected)
Complexity: Medium Impact: High - adds a second detection method
6. OTA (Over-The-Air) Updates
Flash new firmware via WiFi without USB.
// ESP-IDF has built-in OTA support
// Pi serves firmware binary via HTTP
// ESP32 downloads and flashes
// Requires dual OTA partition scheme
Complexity: Medium (partition table change needed) Impact: High - no more USB flashing
7. ESP-NOW Mesh
Direct ESP32-to-ESP32 communication without router.
// Active CSI: ESP32-A sends, ESP32-B measures CSI
// More reliable than passive router beacon monitoring
// Can work even if WiFi router goes down
Complexity: High (requires re-architecting firmware) Impact: High - better CSI quality
8. Temperature Reporting
ESP32 has internal temperature sensor.
// Read chip temperature
// Send with CSI data or as separate status packet
// Useful for monitoring device health
Complexity: Low Impact: Low - monitoring
9. mDNS Auto-Discovery
Announce device on network, no need for static IPs.
// Register as: <device-name>.local
// Pi discovers sensors automatically
// No manual IP configuration needed
Complexity: Low Impact: Medium - easier deployment
10. Watchdog + Auto-Recovery
Better error handling and self-healing.
// Monitor WiFi connection, reconnect on drop
// Monitor UDP send failures
// Track heap fragmentation
// Reboot if stuck for >60 seconds
Complexity: Low Impact: Medium - reliability
Priority Order (Recommended)
| Priority | Feature | Why |
|---|---|---|
| 1 | Remote commands | Remote reboot + identify = essential |
| 2 | LED status | Easy win, helps debugging |
| 3 | OTA updates | Stop walking to each sensor with USB |
| 4 | Adaptive rate | Save CPU/power when idle |
| 5 | mDNS | Easier deployment |
| 6 | BLE scanning | Second detection method |
| 7 | On-device processing | Bandwidth optimization |
| 8 | Temperature | Nice to have |
| 9 | ESP-NOW mesh | Major rewrite, big payoff |
| 10 | Watchdog improvements | Production hardening |
ESP-CSI Tools
Python CSI Parser (get-started/tools/)
csi_data_read_parse.py- PyQt5 GUI for live CSI visualization- Shows amplitude and phase plots in real-time
ESP Radar Console (esp-radar/console_test/)
- Interactive console for testing CSI features
- Includes
esp_csi_tool.pyCLI and GUI tools - Built-in presence detection algorithms