OCPP 2.Lite (OCPP for Resource-Constrained Devices)

OCPP 2.0.1 on resource-constrained devices

Updates in version 2 (July 2025): Version 2 of the OCPP 2.Lite whitepaper adds two case studies that demonstrate that it is feasible to create an OCPP 2.0.1 implementation on a microcontroller. The case studies in appendix B and C are from MicroOCPP and OpenOCPP and include size metrics. Both implementations are available as open source.

This OCPP whitepaper addresses the challenges of implementing the Open Charge Point Protocol (OCPP) 2.0.1 on resource-constrained devices, such as microcontrollers used in lightweight electric vehicle charging stations. With limited RAM, ROM, and flash memory available, it is impractical to deploy the entire protocol. The focus is on achieving a minimal yet compliant implementation, prioritizing the “Core” profile of OCPP while omitting
optional features that are not essential for basic functionality.

Key strategies include minimizing firmware size, reducing memory usage, and optimizing message handling. For example, read-only variables avoid the need for embedded databases, while smaller TLS buffer sizes help reduce memory demands. Real-world benchmarks from MicroOCPP demonstrate that a streamlined implementation can operate within 50 kB of RAM and 200 kB of ROM, making it viable for low-resource environments.

By tailoring OCPP to resource-limited devices, this approach ensures interoperability with existing systems while enabling cost-effective deployment of charging infrastructure. This balance between efficiency, scalability, and compliance is critical to supporting the growth of EV charging networks.