Hardware Guide
Espressif's ESP32-C3 is a solid choice for people counting using Edge Impulse. The risc-v core at 160 MHz with 400 KB SRAM accommodates 200 KB models with room for application logic.
| Spec | ESP32-C3 |
|---|---|
| Processor | Single-core RISC-V @ 160 MHz |
| SRAM | 400 KB |
| Flash | Up to 4 MB (external) |
| Key Features | RISC-V architecture, Ultra-low cost, Hardware crypto acceleration |
| Connectivity | Wi-Fi 802.11 b/g/n, Bluetooth 5.0 LE |
| Price Range | $1 - $3 (chip), $4 - $10 (dev board) |
With 400 KB of internal SRAM, the ESP32-C3 delivers 2.1x the 192 KB minimum needed for people counting. The 200 KB quantized model fits in the tensor arena with enough remaining capacity for input buffers and core application logic. More demanding features (multi-sensor fusion, large protocol stacks) may require careful allocation planning. The ESP32-C3 provides 4 MB of flash memory, which comfortably houses the Edge Impulse runtime, the 200 KB model binary, application firmware, and OTA update partitions for field upgrades. Flash usage is well within budget for this configuration. As a single-core RISC-V chip, the ESP32-C3 is cost-optimized ($1-3) for high-volume deployments. Its 400 KB SRAM handles most sensor-based ML models. No hardware ML acceleration, but the low power consumption makes it ideal for battery-powered edge nodes. People Counting requires camera input. The ESP32-C3 lacks native peripheral support for some of these sensors, requiring external interface circuitry. A camera interface (DVP/DCMI) is not available — SPI-based camera modules may work but with reduced frame rates. Evaluate whether the peripheral gap justifies an alternative MCU with native support. Edge Impulse provides an end-to-end workflow: data collection from the ESP32-C3 via serial or WiFi, cloud-based training with auto-quantization, and deployment via C++ library export or Arduino library. The platform estimates on-device RAM and flash usage before deployment, reducing trial-and-error. Wi-Fi-connected boards can use the Edge Impulse daemon for direct data ingestion. At $1-3 per chip ($4-10 for dev boards), the ESP32-C3 is a reasonable investment for people counting deployments. 16 PlatformIO-listed boards provide decent hardware selection. Key ESP32-C3 features for this workload: RISC-V architecture, Ultra-low cost, Hardware crypto acceleration.
Create Edge Impulse project for ESP32-C3
Sign up at edgeimpulse.com and create a new project for people counting. Install the Edge Impulse CLI (npm install -g edge-impulse-cli). Connect the ESP32-C3 board directly via the EI firmware image, or the data forwarder to stream camera data from your Espressif development board.
Collect camera training data
Connect a camera module (e.g., OV2640 via DVP/SPI) to the ESP32-C3. Use Edge Impulse's data forwarder or direct board connection to stream samples to the cloud. Collect 1000+ labeled samples across all classes. Capture images at the model input resolution (96×96 or lower).
Train model in Edge Impulse Studio
Design an impulse with the appropriate signal processing block (image preprocessing). Add a quantized MobileNet-SSD or YOLO-Tiny learning block. Train and evaluate — Edge Impulse shows estimated latency and memory usage for the ESP32-C3. Target under 160 KB model size and under 400 KB peak RAM.
Deploy and validate on ESP32-C3
Deploy via Edge Impulse CLI (edge-impulse-cli export) or download the C++ library. Allocate a tensor arena of 300-500 KB in a static buffer. Run inference on live camera data and compare predictions against your test set. Report results via MQTT or HTTP for remote validation. Measure inference latency and peak RAM usage to verify they meet application requirements.
Espressif xtensa-lx7 at 240 MHz with 512 KB SRAM. $3-8 per chip. Excellent rated.
Espressif xtensa-lx6 at 240 MHz with 520 KB SRAM. $2-5 per chip. Good rated.
Espressif risc-v at 160 MHz with 512 KB SRAM. $1-3 per chip. Good rated.
Connect cameras to on-device inference — design detection workflows visually and compile to optimized firmware.
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