wolfTPM is the leading TPM library for embedded and baremetal applications. It is widely used in aerospace, military, and medical systems because the wolfSSL TPM 2.0 library is designed specifically for embedded systems. wolfTPM offers a low memory footprint and supports all of the TPM 2.0 commands and operations; as well as provids examples of: attestation, NVRAM usage, secure storage, and sealing.
Today, we have expanded on the new TPM 2.0 feature called Extra GPIO, by adding support for the newest variant of NPCT75x modules by Nuvoton.
It is now possible to protect and control GPIO by using TPM 2.0 authorization. This way, extra GPIO on the TPM chip becomes a great tool for signaling of critical events across subsystems.
Since, wolfTPM already offers support for extra GPIO for ST33 modules from STMicroelectronics. Here is a brief comparison of the GPIO capabilities between ST33 and NPCT75x :
| Manufacturer | Model | Extra GPIO availability | GPIO modes |
| Nuvoton | NPCT75x | 2 GPIO for SPI & I2C | 3 output modes |
| STMicroelectronics | ST33 | 2 GPIO for SPI 4 GPIO for I2C |
6 modes in total |
In safety-critical systems, extra GPIO control through the TPM 2.0 module provides signaling for security events and important changes of the system state. Such use cases are observed in the rising railway IoT automation and in modern automotive systems.
We want to thank the team at Nuvoton led by Mr. Oren and the amazing field application engineer Ms. Dana for collaborating on this project.
If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.