Datasheet

dsPIC33EPXXXGP50X, dsPIC33EPXXXMC20X/50X AND PIC24EPXXXGP/MC20X
DS70657G-page 138  2011-2013 Microchip Technology Inc.
In addition, DMA transfers can be triggered by timers
as well as external interrupts. Each DMA channel is
unidirectional. Two DMA channels must be allocated to
read and write to a peripheral. If more than one channel
receives a request to transfer data, a simple fixed
priority scheme based on channel number, dictates
which channel completes the transfer and which
channel, or channels, are left pending. Each DMA
channel moves a block of data, after which, it generates
an interrupt to the CPU to indicate that the block is
available for processing.
The DMA controller provides these functional
capabilities:
• Four DMA channels
• Register Indirect with Post-Increment
Addressing mode
• Register Indirect without Post-Increment
Addressing mode
• Peripheral Indirect Addressing mode (peripheral
generates destination address)
• CPU interrupt after half or full block
transfer complete
• Byte or word transfers
• Fixed priority channel arbitration
• Manual (software) or automatic (peripheral DMA
requests) transfer initiation
• One-Shot or Auto-Repeat Block Transfer modes
• Ping-Pong mode (automatic switch between two
SRAM start addresses after each block transfer is
complete)
• DMA request for each channel can be selected
from any supported interrupt source
• Debug support features
The peripherals that can utilize DMA are listed in
Table 8-1.
TABLE 8-1: DMA CHANNEL TO PERIPHERAL ASSOCIATIONS
Peripheral to DMA Association
DMAxREQ Register
IRQSEL<7:0> Bits
DMAxPAD Register
(Values to Read from
Peripheral)
DMAxPAD Register
(Values to Write to
Peripheral)
INT0 – External Interrupt 0 00000000 ——
IC1 – Input Capture 1 00000001 0x0144 (IC1BUF) —
IC2 – Input Capture 2 00000101 0x014C (IC2BUF) —
IC3 – Input Capture 3 00100101 0x0154 (IC3BUF) —
IC4 – Input Capture 4 00100110 0x015C (IC4BUF) —
OC1 – Output Compare 1 00000010 — 0x0906 (OC1R)
0x0904 (OC1RS)
OC2 – Output Compare 2 00000110 — 0x0910 (OC2R)
0x090E (OC2RS)
OC3 – Output Compare 3 00011001 — 0x091A (OC3R)
0x0918 (OC3RS)
OC4 – Output Compare 4 00011010 — 0x0924 (OC4R)
0x0922 (OC4RS)
TMR2 – Timer2 00000111 ——
TMR3 – Timer3 00001000 ——
TMR4 – Timer4 00011011 ——
TMR5 – Timer5 00011100 ——
SPI1 Transfer Done 00001010 0x0248 (SPI1BUF) 0x0248 (SPI1BUF)
SPI2 Transfer Done 00100001 0x0268 (SPI2BUF) 0x0268 (SPI2BUF)
UART1RX – UART1 Receiver 00001011 0x0226 (U1RXREG) —
UART1TX – UART1 Transmitter 00001100 — 0x0224 (U1TXREG)
UART2RX – UART2 Receiver 00011110 0x0236 (U2RXREG) —
UART2TX – UART2 Transmitter 00011111 — 0x0234 (U2TXREG)
ECAN1 – RX Data Ready 00100010 0x0440 (C1RXD) —
ECAN1 – TX Data Request 01000110 — 0x0442 (C1TXD)
ADC1 – ADC1 Convert Done 00001101 0x0300 (ADC1BUF0) —