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Issue #204 July 2007
Are You Up for 16 Bits?
A look at Microchip's Family of 16 -Bit Microcontrollers
by Jeff Bachiochi
Start | Microchip's 16-Bit Family |Eeny, Meeny, Miny, Moe | PIC24F | PIC24H | Need DSP? | dsPIC30/33 | Standard Features | Peripheral Pin Select | DSP | DMA | Jump-Start PCBs | SMPS for $750 | Think, Enter, Win | Sources & PDF
PERIPHERAL PIN SELECT
One of the problems with low-pin-count microcontrollers is that they are limited by their available I/O pins. As a result, the family has more peripherals than the part has pins to support. Peripheral pin select (PPS) does away with this limitation by allowing certain peripherals to be dynamically mapped to a group of I/O pins. Although a single pin can be shared among peripherals, you should be careful. This opens the door for some pretty tricky configurations. Because this is a dynamic function, some safeguards are implemented to lock the configuration registers and report if a malfunction (illegal change in configuration) occurs. Change-of-state inputs have been a standard peripheral on microcontrollers for some time now. They are practical for implementing a wakeup on key-press functions. COS on the 16-bit microcontrollers is now implemented with dynamic mapping. Each pin mapped for COS can enable an internal pullup (reducing the need for external components).
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