A crystalless metering SOC chip and its clock acquisition method

Abstract

The invention discloses a crystalless metering SoC chip and a clock acquisition method thereof. The method comprises: receiving training bytes sent by an external main control MCU through a serial port UART; Count the time interval Tref between two falling edges to obtain the count value Nrc; use Fideal and Nrc to calculate the estimated baud rate Fibaud of the training byte sent by the external master MCU, and obtain the training byte sent by the external master MCU by looking up the table The actual baud rate Fbaud, the time interval Tref is obtained according to Fbaud; the actual clock frequency Frc of the RC clock module is calculated by using Nrc and Tref, and the clock frequency of the RC clock module is adjusted according to the difference between Frc and the preset clock frequency Fideal to obtain the RC clock The adjusted clock frequency Frcc of the module. The method realizes that the crystal-free metering SoC chip itself can obtain the clock frequency without using an external crystal to provide the clock frequency, thereby reducing the system cost and improving the reliability of obtaining the clock frequency.

Description

technical field [0001] The invention relates to the technical field of electrical parameter measurement, in particular to a crystalless metering SoC chip and a clock acquisition method thereof. Background technique [0002] In electrical parameter measurement applications, such as smart sockets, smart home appliances, and smart meters, the implementation scheme of separating the metering module from the main microcontroller MCU module is often used. With the implementation of the international regulation IR46 for smart meters, the metering module is required to implement For metering functions related to regulations, the external communication control module, that is, the MCU part, cannot affect the function and performance of the metering module. It can be seen that the metering module designed based on the metering SoC (System on Chip) is combined with the multi-functional communication encryption main control MCU module implementations will dominate. [0003] In this app...

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Problems solved by technology

[0003] In this application, the core chip of the main control microcontroller module is the microcontroller chip, and the core chip of the metering module is the metering SoC. Both the microcontroller chip and the metering SoC need an external crystal to achieve the required clock accuracy. Without an external crystal, the metrology SoC cannot acquire the required clock frequency and cannot perform the measurement application

Moreover, the added external crystal will increase the system cost, and the external crystal itself will have the risk of stopping the vibration. Once the vibration stops, the metering SoC will not be able to obtain the required clock frequency, which will reduce the performance of the metering module in the metering SoC. clock reliability

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