Designing Embedded Hardware

A Bigger PIC

In this section, we’ll look at the PIC16C73 processor. For a midrange PIC, the design is not dissimilar to the simpler PIC we’ve already looked at. The only real difference is that the processor has more pins, more I/O, and more functionality. We’ll look at what you can do with its various I/O subsystems in Part III of this book.

The address space for this processor is shown in Figure 5-6.

Figure 5-6. PIC16C73 address space (Reference: PIC16C73 datasheet)

The schematic for this processor is shown in Figure 5-7. This processor has 4K words of program memory, 192 bytes of RAM, and a variety of I/O subsystems, such as three timer modules, SPI, I²C, a UART, five channels of analog input, and up to 22 digital I/O pins.

Figure 5-7. PIC16C73 processor and support components

This processor has one power pin (VDD) and two ground pins (VSS). As always, power is decoupled to ground with a small capacitor (C3). The only other requirements are some form of clock generation, in this case provided by a crystal, X1, and two decoupling capacitors, C1 and C2. The clock could just as easily have been provided using an RC circuit, as we saw with the 12C508. The reset input, MCLR , is tied directly to the power supply, so that is permanently inactive. In this case, we are relying on the processor’s ...