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All case studies
router
Physical Security
Connected Access Control Board
STM32F4 + ESP32 dual-processor
A cloud-connected single-door access controller built as a dual-processor system — an STM32F4 host owning the security-critical real-time logic, an ESP32 handling WiFi and BLE — so the radio never touches the access path. MQTT cloud control, with OTA over both MQTT and BLE.
Host + coproc
Radio off the security path
2 OTA paths
MQTT remote, BLE on-site
Cloud-native
Single-board deployment
- Client
- Access-control product line (name withheld — NDA)
- Delivery
- Delivered by our founder at IoTech Designs
- Role
- Research & Solution Architect — architecture and firmware
- Timeline
- 2019 – 2021
Stack
STM32F4 (host) ESP32 (connectivity) Embedded C WiFi BLE MQTT Dual-path OTA
help The problem
The multi-credential controller scaled across many doors over RS485, but some installations need the opposite: a single self-contained connected door — no wired controller network, just the door, the cloud and a phone. That means putting real-time access-control logic and modern wireless connectivity on one board without letting the radio stack interfere with security-critical timing.
build What we built
- A dual-processor architecture: an STM32F4 host owning access-control logic and real-time I/O, with an ESP32 as a dedicated connectivity coprocessor for WiFi and BLE — keeping the radio's workload off the security-critical path.
- The same access-control feature set as the multi-door system — credential handling, access logic, tamper detection — scoped to single-board control.
- MQTT connectivity for cloud-based control and monitoring over WiFi.
- Dual-path OTA: firmware updates delivered over both MQTT for remote and BLE for on-site, so a device can be updated from the field or from a phone standing next to it.
check_circle The result
- done A connected, self-contained access-control board complementing the networked multi-door platform — same security features, cloud-native deployment model.
- done Multi-processor system architecture, host/coprocessor partitioning, cloud and BLE connectivity, and robust multi-path OTA on security-critical hardware.