PIC Microcontroller Reset Procedure: A Comprehensive Guide

The PIC microcontroller is a popular choice among electronics enthusiasts and professionals alike due to its ease of use, versatility, and wide range of applications. However, like any other microcontroller, the PIC can sometimes malfunction or get stuck, requiring a reset to restore its normal functioning. In this article, we will delve into the PIC reset procedure, exploring the different types of resets, the reset circuitry, and the steps involved in resetting a PIC microcontroller.

Types of Resets

A PIC microcontroller can be reset in several ways, each with its own advantages and disadvantages. The three main types of resets are:

• Power-on Reset (POR): This type of reset occurs when the power is first applied to the microcontroller. The POR is used to initialize the microcontroller’s registers and set up the clock and other essential systems.
• Brown-out Reset (BOR): A brown-out reset occurs when the power supply voltage falls below a certain threshold, causing the microcontroller to reset. This type of reset is useful in preventing damage to the microcontroller and other components in the system.
• Manual Reset: A manual reset is initiated by the user, usually by pressing a reset button or applying a reset signal to the microcontroller’s reset pin.

Reset Circuitry

The reset circuitry is a critical component of the PIC microcontroller, responsible for detecting and responding to reset signals. The reset circuitry typically consists of:

• Reset Pin: The reset pin is a dedicated input pin that receives the reset signal. When the reset pin is asserted, the microcontroller initiates a reset sequence.
• Reset Switch: The reset switch is a push-button switch or other type of switch that connects the reset pin to ground or Vcc, depending on the microcontroller’s requirements.
• Reset Capacitor: The reset capacitor is used to filter out noise and debounce the reset signal, ensuring that the microcontroller only responds to a valid reset signal.

PIC Reset Procedure

The PIC reset procedure involves several steps, which are outlined below:

1. Power-down the microcontroller: Before initiating a reset, make sure the microcontroller is powered down. This ensures that the microcontroller is in a known state and reduces the risk of damage during the reset process.
2. Assert the reset signal: Apply a reset signal to the reset pin, either by pressing the reset button or applying a voltage to the reset pin. The reset signal should be asserted for a minimum of 2-3 clock cycles to ensure that the microcontroller detects the reset signal.
3. Wait for the reset sequence to complete: After asserting the reset signal, wait for the reset sequence to complete. This can take several milliseconds, depending on the microcontroller’s clock speed and other factors.
4. Release the reset signal: Once the reset sequence is complete, release the reset signal by removing the voltage from the reset pin or releasing the reset button.
5. Wait for the microcontroller to boot up: After releasing the reset signal, wait for the microcontroller to boot up and initialize its registers and systems. This can take several milliseconds to several seconds, depending on the microcontroller’s configuration and application.

Resetting a PIC Microcontroller in Software

In addition to the hardware reset procedure, it is also possible to reset a PIC microcontroller in software using a technique called a “software reset.” A software reset involves writing a specific sequence of instructions to the microcontroller’s program counter, causing the microcontroller to jump to the reset vector and initiate a reset sequence.

To perform a software reset, follow these steps:

1. Save the current state: Before initiating a software reset, save the current state of the microcontroller’s registers and variables. This ensures that the microcontroller can restore its state after the reset.
2. Write the reset sequence: Write the specific sequence of instructions to the microcontroller’s program counter, causing the microcontroller to jump to the reset vector.
3. Wait for the reset sequence to complete: After writing the reset sequence, wait for the reset sequence to complete. This can take several milliseconds, depending on the microcontroller’s clock speed and other factors.
4. Restore the saved state: Once the reset sequence is complete, restore the saved state of the microcontroller’s registers and variables.

Conclusion

In conclusion, the PIC reset procedure is an essential aspect of working with PIC microcontrollers. By understanding the different types of resets, the reset circuitry, and the steps involved in resetting a PIC microcontroller, developers can ensure that their applications are reliable and robust. Whether you are a seasoned developer or just starting out with PIC microcontrollers, this comprehensive guide has provided you with the knowledge and insights you need to master the PIC reset procedure.

References

For more information on the PIC reset procedure, refer to the following resources:

• PIC Microcontroller Datasheet: The official datasheet for the PIC microcontroller provides detailed information on the reset procedure, including the reset circuitry and the steps involved in resetting the microcontroller.
• PIC Microcontroller Programming Manual: The programming manual for the PIC microcontroller provides information on how to reset the microcontroller in software, including the specific sequence of instructions required to initiate a software reset.
• Online Forums and Communities: Online forums and communities, such as the Microchip forum and the PIC microcontroller subreddit, provide a wealth of information and resources on the PIC reset procedure, including tutorials, examples, and troubleshooting tips.