PIC24 support library

The PIC24 support library is divided into external components, internal components, and tools used in creating the library. External components should be called by the typical user to set up the PIC, communicate over the UART, I²C bus, etc. Internal components include both implementation details and information on adding support for PIC24 processors not currently supported by this library. Following these three sections is a library function summary, listing all functions available in the library.

A simple example which echos characters via the UART:

#include "pic24_all.h"
int main(void) {
  // Set up clock, heartbeat, UART, print welcome message
  configBasic(HELLO_MSG);
  while (1) {
    // Echo characters
    outChar(inChar());
  }
  return 0;
}

Library components

External library components

• Development support
  • A single header file to include all the files below, in pic24_all.h
  • Delay routines
  • Definition of generic data types
  • Setup of IO ports
  • Unit testing / assertions, in pic24_unittest.h
  • Miscellanous utilities, in pic24_util.h
• Peripheral support
  • Analog to digital converter routines, in pic24_adc.h
  • Direct memory access (DMA) routines, in pic24_dma.h
  • Enhanced controller area network (ECAN) routines, in pic24_ecan.h
  • Read/write of FLASH, in pic24_flash.h
  • Setup of timers, in pic24_timer.h
  • Serial communication support, in pic24_serial.h
  • I²C support, in pic24_i2c.h
  • SPI support, in pic24_spi.h

Internal library components

• User-configurable library settings, in pic24_libconfig.h
• Clock configuration, in pic24_clockfreq.h and pic24_clockfreq.c
• Configuration bit settings, in pic24_configbits.c
• UART support in pic24_uart.h and pic24_uart.c, which is typically called by routines in pic24_serial.h.

Tools used to create the code

SCons provides automated library building and testing. See SConstruct.py for documentation of this process. Capabilities include:

• Automated build of all example code in the textbook
• Support for multiple copies of a device, such as the UART, I²C, and SPI, is auto-generated from templates which contain a single copy of the code. The templates/ directory contains the templates from which these files are built.

To maintain a consistent style, a batch file which runs the Artistic Style code formatter is available as runAStyle.bat.

Library function summary

This section lists all the commands available in the various sections of the library, providing a quick overview of the library's capabilities.

Delay routines

The file pic24_delay.h defines:

• DEBOUNCE_DLY, DELAY_MS(ms), DELAY_US(us), CYCLES_PER_MS, CYCLES_PER_US

Generic data types

The file in pic24_generic.h defines:

• Signed integers: int8, int16, int32, int64
• Unsigned integers: uint8, uint16, uint32, uint64
• Unions: union16, union32, union64

Setup of IO ports

The file pic24_ports.h includes files which define:

• High-level port configuration: CONFIG_Rxy_AS_DIG_OUTPUT(), CONFIG_Rxy_AS_DIG_OD_OUTPUT(), CONFIG_Rxy_AS_DIG_INPUT(), CONFIG_ANx_AS_ANALOG()
• Low-level port configuration: ENABLE_Rxy_ANALOG(), DISABLE_Rxy_ANALOG(), CONFIG_RPy_AS_DIG_PIN(), ENABLE_Rxy_OPENDRAIN(), DISABLE_Rxy_OPENDRAIN(), ENABLE_Rxy_PULLUP(), DISABLE_Rxy_PULLUP(), ENABLE_Rxy_CN_INTERRUPT(), DISABLE_Rxy_CN_INTERRUPT()
• Remappable peripherlal support: CONFIG_xxx_TO_RP(pin)