Overview

There is a range of PIC microcontrollers that manages to squeeze a large number of features into a tiny 8-pin package. The 8-pin device most like the PIC16F54 is the PIC12F508 (the 12 in the name tells us that this is an 8-pin device). Surprisingly, this little PIC microcontroller offers up to 6 I/O pins (the other two are power supply pins). It needs no external oscillator (e.g., crystal or RC), as it has an in-built 4-MHz oscillator, and even offers a feature that allows external signals to wake it up from the sleep state. For any application where a small size is advantageous and 6 I/O pins are sufficient, these PIC microcontrollers are invaluable.

The PIC12F50x series consists of two models (the PIC12F 508 and PIC12F 509) shown in Fig. 9.1, with a third model (the PIC12F 510) under development at the time of publication. The 'F509 has more memory (more program memory, and more GPFs) than the 'F508. The 'F510 will be similar to the 'F509 but with the added feature of built-in analog-to-digital conversion (this is discussed further in Chapter 10).

Figure 9.1

9.1 Differences from the PIC16F54

There are a few differences in the way these PIC microcontrollers work, most of which are illustrated in the file registers. Figure 9.2 shows the file register arrangement for the PIC12F50x series.

Figure 9.2: Map of File Registers for PIC12F508