What is the clocking mechanism in Microchip PIC hardware?

1 Clock Sources

PIC hardware can use different types of clock sources to generate the clock signal that drives the microcontroller. The most common are an internal RC oscillator, an external crystal or resonator, and an external clock. An internal RC oscillator is a low-cost and low-power option, but it has a low accuracy and stability due to temperature and voltage variations. An external crystal or resonator is a more expensive and power-consuming option, as it requires additional components such as capacitors and resistors; however, it provides a high-accuracy and high-stability clock signal. An external clock is an external signal provided by another device, such as a clock generator or another microcontroller. It can have any frequency and shape, but it must meet the specifications of the PIC hardware.

2 Clock Modes

PIC hardware can operate in different clock modes, depending on the type of clock source and the configuration settings. The most common ones are LP (Low Power) mode, which uses an external crystal or resonator with a frequency of 32 kHz or less; XT (Crystal) mode, which uses an external crystal or resonator with a frequency of 0.4 MHz to 20 MHz; HS (High Speed) mode, which uses an external crystal or resonator with a frequency of 4 MHz to 40 MHz; and INTOSC (Internal Oscillator) mode, which uses the internal RC oscillator with a frequency of 31 kHz to 32 MHz. These modes are suitable for applications that require low power consumption, high accuracy and stability, high speed and performance, or do not require an external clock source respectively.

3 Clock Switching

PIC hardware can switch between different clock sources and modes during runtime, depending on the application needs and conditions. This feature, referred to as clock switching, is enabled or disabled by setting or clearing the SCS bits in the OSCCON register. Clock switching can be beneficial in several ways, such as saving power by switching to a lower frequency or low power mode when necessary, improving reliability by switching to an alternative clock source if the primary one fails or becomes unstable, and changing functionality by switching to a different clock mode to support various functions or peripherals, such as timers, serial communication, or analog-to-digital conversion.

4 Clock Calibration

PIC hardware can adjust the frequency of the internal RC oscillator to compensate for the variations caused by temperature and voltage changes, called clock calibration. This can be done by using the OSCCAL register or the FSCM (Fail-Safe Clock Monitor) module. Clock calibration can be useful for improving accuracy, maintaining stability, and enhancing performance. It can fine-tune the frequency of the internal RC oscillator to match the expected value or external reference, reducing error margin. Additionally, it can monitor and correct any frequency drifts or deviations from the normal range, preventing malfunction or data loss. Furthermore, it can optimize the frequency of the internal RC oscillator to achieve a balance between speed and power consumption, increasing efficiency and quality of the application.

5 Here’s what else to consider

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