Traditionally, the microcontroller stack has only been used as a storage space for return addresses of sub- routines or interrupt routines, where all ‘push’ and ‘pop’ operations were hidden. For the most part, users had no direct access to the information on the stack. The PIC18 microcontroller diverges from this tradition slightly. With the new PIC18 core, users now have access to the stack and can modify the stack pointer and stack data directly. Having such levels of access to the stack allows for some unique and interesting programming possibilities. This application note describes specific information, registers, and instructions related to accessing the stack. An example is also included demonstrating a very simple task manager, an essential element for a real-time operating system (RTOS).M AN818 Manipulating the Stack of the PIC18 Microcontroller Author: Ross M. Fosler The pointer to the top of the stack is provided in register Microchip Technology Inc. STKPTR. The pointer is only five-bits wide, which accounts for a stack depth of 32 words. However, the first location is not counted, since it is not physically a INTRODUCTION memory location in the stack. The first location always Traditionally, the microcontroller s……