UPC EETAC Bachelor's Degree in Telecommunications Systems and in Network Engineering EEL

 

  

Power-ON reset of sequential systems and microcontrollers

L5.2

L9.2

Clear direct (CD), master reset (MCRL)

The idea of initialising a sequential system to a known state

Power ON reset

Fig. 1. Waveforms.

 

MCLR_L

Fig. 2. Example of typical external MCLR_L circuit (CD_L) in PIC EXPLORER 8 development kit schematic. R18·C18 is the circuit time contant. R23 is intended for pin protection.

 

Reset circuitry for PIC18F4520

Fig. 3. Reset circuit block diagram from PIC18F4520 internal architecture. MCLR_L pushbutton does the same function than the RESET assembler instruction. See circuit's datasheet chapter 4 to read about the various kinds of reset options.