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THROUGH THE LOOKING GLASS

Taking a Look at the PIC18Cxxx Series
by David Brobst

Start ý PIC18Cxxx Chips ý Memory ý Data Memory ý Advanced Indirect Addressing ý Deep and Accessible Stack ý Interrupts ý Power-On Features ý Clock Speed ý 10-Bit A/D ý Hardware Multiplier ý Timers ý CCP/PWM ý USART ý I²C Master ý Table Read/Write ý Current Status ý Sources and PDF

MEMORY

A second welcome feature is the amount of both data and program memory available in the chips. Indeed, while the current Big Bertha of the PIC18Cxxx family is limited to 16 KB of program memory, the architecture has been designed with the future in mind. The device is capable of addressing 1 MB of instructions. In addition to that, the quantity of data memory is a welcome relief to anyone who has ever struggled to cram just one more variable into a program. Again, the amount of data memory in the introductory chips is just the tip of the iceberg. The data addresses have been set up to accommodate up to 4 KB of data memory in the future. Figure 2 shows the program memory for the PIC18Cxxx family.

Figure 2ýThe program memory of the 18Cxxx family is set up in a linear manner and can accommodate up to 1 MB of instructions.

A quick perusal of Table 1 shows that the PIC18Cxxx family has upped the ante over the mid-range controllers with increased clock speed, resolution A/D, serial support, and more special functions. Most of these features will be explored in detail later in the article.

Taking all of these features into consideration along with the literature provided for the PIC18Cxxx family, the direction Microchip is taking is clear. With the increased clock speed, hardware multiplier, and higher resolution A/Ds, the PIC18Cxxx family is placed as a low-end DSP solution. For example, it could be seen easily as a dedicated motor controller (lower-end DSP), but an advanced graphics card would be out of its league.

With its ample linear program memory and loads of data memory, the chip becomes more amenable to compilers and coding tools. The PIC18Cxxx family is more hospitable to C compilers than the earlier families of PIC microcontrollers. Indeed, a C compiler with libraries for the PIC18Cxxx family is already being provided. With all of this in mind, letýs look at some of the new features in greater detail.

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