Features and functions of PIC series microcontroller data memory (Part 1)

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Features and functions of PIC series microcontroller data memory (Part 1) [Copy link]

Although there are many varieties of PIC series microcontrollers, the data memory settings of the internal hardware resources of each product are still very regular. The author takes PIC16C71A and PIC16C63/65/65A as examples to check the structure of their on-chip data memory, find out their characteristics and explain the main functions of some registers for users to quickly program. Table 1 and Table 2 are the resource tables of the on-chip data memory of PIC16C71A and PIC16C63/65/65A products respectively. The resources of the on-chip data memory structure of other series products are very similar to those in Table 1 and Table 2. The only difference is the type and number of on-chip functional components (PIC16C57/58 microcontrollers have 4 storage banks). The author introduces the characteristics and main functions of Table 1 and Table 2 from the following aspects.

　　1? Unified addressing All types of data memory of PIC series microcontrollers work and are addressed in register mode. Special registers include timing register TMRO, selection register OPTION (also known as option register), program counter PCL, status register STATUS, indirect addressing registers INDF and FSR, port I/O registers (such as PORTA, PORTB...) and corresponding port I/O control registers (also known as port I/O data direction registers, such as TRIAS, TRISB...), holding register PCLATH and interrupt control register INTCON, etc. The above special registers are common to PIC16C63/65/65A and PIC16C71A. They not only have the same register names and functions, but also the same register addresses. If you look at other PIC microcontrollers, such as PIC16C62/62A/64/64A, PIC16C71/72/73/73A/74/74A, PIC16C8X..., their special register names are the same as the above, and their addresses are also exactly the same as the above. It can be seen that although there are many varieties of PIC series microcontrollers, it is not difficult to learn after mastering their rules.
　　Different types of PIC microcontrollers have different internal resources in data memory only in terms of function type and quantity. For example, the PIC16C71A type has 18 pins and its main function is to have an 8-bit A/D conversion unit with 4 A/D channel analog inputs. Therefore, in Table 1, the dedicated registers related to its A/D conversion unit are ADRES (used to store the numerical results of A/D conversion), A/D control register ADCON0 (used to control the operation of the A/D converter) and A/D control register ADCON1 (used to control the function of selecting the A/D pin). For the PIC16C65/65A type, it has 40 pins and its functions are stronger than those of the PIC16C71A microcontroller. Therefore, the types of dedicated registers in the data memory Table 2 are much more than those in Table 1.
　　Each register unit of the dedicated register has a corresponding fixed purpose. They can be divided into two categories: one is used for CPU operation (such as INDF and FSR, STATUS, PCL...); the other is used to control the operation of peripheral function chips.