PIC32MX5XX_11 Datasheet, PDF (239/256 Pages) Microchip Technology – High-Performance, USB, CAN and Ethernet 32-bit Flash Microcontrollers

APPENDIX A:
MIGRATING FROM
PIC32MX3XX/4XX TO
PIC32MX5XX/6XX/7XX
DEVICES
This appendix provides an overview of considerations
for migrating from PIC32MX3XX/4XX devices to the
PIC32MX5XX/6XX/7XX family of devices. The code
developed for the PIC32MX3XX/4XX devices can be
ported to the PIC32MX5XX/6XX/7XX devices after
making the appropriate changes outlined below.
A.1 DMA
PIC32MX5XX/6XX/7XX devices do not support
stopping DMA transfers in Idle mode.
A.2 Interrupts
PIC32MX5XX/6XX/7XX devices have persistent
interrupts for some of the peripheral modules. This
means that the interrupt condition for these peripherals
must be cleared before the interrupt flag can be
cleared.
For example, to clear a UART receive interrupt, the
user application must first read the UART Receive
register to clear the interrupt condition and then clear
the associated UxIF flag to clear the pending UART
interrupt. In other words, the UxIF flag cannot be
cleared by software until the UART Receive register is
read.
PIC32MX5XX/6XX/7XX
Table A-1 outlines the peripherals and associated
interrupts that are implemented differently on
PIC32MX5XX/6XX/7XX versus PIC32MX3XX/4XX
devices.
In addition, on the SPI module, the IRQ numbers for the
receive done interrupts were changed from 25 to 24
and the transfer done interrupts were changed from 24
to 25.
TABLE A-1:
Module
Input Capture
SPI
UART
ADC
PMP
PIC32MX3XX/4XX VERSUS PIC32MX5XX/6XX/7XX INTERRUPT IMPLEMENTATION
DIFFERENCES
Interrupt Implementation
To clear an interrupt source, read the Buffer Result (ICxBUF) register to obtain the number of
capture results in the buffer that are below the interrupt threshold (specified by ICI<1:0> bits).
Receive and transmit interrupts are controlled by the SRXISEL<1:0> and STXISEL<1:0> bits,
respectively. To clear an interrupt source, data must be written to, or read from, the SPIxBUF
register to obtain the number of data to receive/transmit below the level specified by the
SRXISEL<1:0> and STXISEL<1:0> bits.
TX interrupt will be generated as soon as the UART module is enabled.
Receive and transmit interrupts are controlled by the URXISEL<1:0> and UTXISEL<1:0> bits,
respectively. To clear an interrupt source, data must be read from, or written to, the UxRXREG or
UxTXREG registers to obtain the number of data to receive/transmit below the level specified by
the URXISEL<1:0> and UTXISEL<1:0> bits.
All samples must be read from the result registers (ADC1BUFx) to clear the interrupt source.
To clear an interrupt source, read the Parallel Master Port Data Input/Output (PMDIN/PMDOUT)
register.
© 2009-2011 Microchip Technology Inc.
DS61156G-page 239