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Coming soon |
1. Introduction
The system clock manager (SCM) is module responsible for managing CPU system clock source and frequency according to Connectivity purposes. System clock manager module defines different users that can request different configurations. Modules determines which one is best to suit the system and all SCM users needs.
SCM module also steps in low power wake-up phase by applying usable configuration for RF activities.
2. Features
2.1. SCM users principle
The module is based on a client request mechanism. SCM defines users (up to 32) that can request a clock frequency modification. There is a system user SCM_USER_LL_FW and multiple application users can be define in addition to existing SCM_USER_APP.
Among all the requests, the system clock manager determines the one that fulfills all the requests. The best system clock evaluation is realized at each new request.
On one hand, the decrease clock speed request is handled immediately. On the other hand, the increase clock speed request requires more time to setup. It is not blocking; an interrupt mechanism is used to switch to the requested speed. This permits the firmware to keep running at the actual clock speed until the system is ready. Different clock configurations are possible to request, the supported ones are the following:
- HSE32
- HSE16
- PLL (With a dedicated interface for configuration)
The module also handles the configuration of the Flash and SRAM latencies, the CPU wait states, the configuration of the VOS and the AHB5 divider configuration, depending on the determined clock speed. For the other impacted modules or systems, the user shall adequate and adapt the configurations to the newly set CPU system clock frequency.
3. Interfaces
TBD.
4. How to
TBD.