70291E Datasheet, PDF (133/436 Pages) Microchip Technology – High-Performance, 16-bit Digital Signal Controllers

dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04 AND dsPIC33FJ128MCX02/X04
8.0 DIRECT MEMORY ACCESS
(DMA)
Note 1: This data sheet summarizes the features
of the dsPIC33FJ32MC302/304,
dsPIC33FJ64MCX02/X04
and
dsPIC33FJ128MCX02/X04 family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to “Section 38. Direct Mem-
ory Access (DMA) (Part III)” (DS70215)
of the “dsPIC33F/PIC24H Family
Reference Manual”, which is available
from the Microchip web site
(www.microchip.com).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
Direct Memory Access (DMA) is a very efficient mech-
anism of copying data between peripheral SFRs (e.g.,
UART Receive register, Input Capture 1 buffer), and
buffers or variables stored in RAM, with minimal CPU
intervention. The DMA controller can automatically
copy entire blocks of data without requiring the user
software to read or write the peripheral Special Func-
tion Registers (SFRs) every time a peripheral interrupt
occurs. The DMA controller uses a dedicated bus for
data transfers and therefore, does not steal cycles from
the code execution flow of the CPU. To exploit the DMA
capability, the corresponding user buffers or variables
must be located in DMA RAM.
The dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/
X04 and dsPIC33FJ128MCX02/X04 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<6:0> Bits
DMAxPAD Register
Values to Read From
Peripheral
INT0 – External Interrupt 0
IC1 – Input Capture 1
OC1 – Output Compare 1 Data
OC1 – Output Compare 1 Secondary Data
IC2 – Input Capture 2
OC2 – Output Compare 2 Data
OC2 – Output Compare 2 Secondary Data
TMR2 – Timer2
TMR3 – Timer3
SPI1 – Transfer Done
UART1RX – UART1 Receiver
UART1TX – UART1 Transmitter
ADC1 – ADC1 convert done
UART2RX – UART2 Receiver
UART2TX – UART2 Transmitter
SPI2 – Transfer Done
ECAN1 – RX Data Ready
PMP - Master Data Transfer
ECAN1 – TX Data Request
DAC1 - Right Data Output
DAC2 - Left Data Output
0000000
0000001
0000010
0000010
0000101
0000110
0000110
0000111
0001000
0001010
0001011
0001100
0001101
0011110
0011111
0100001
0100010
0101101
1000110
1001110
1001111
—
0x0140 (IC1BUF)
—
—
0x0144 (IC2BUF)
—
—
—
—
0x0248 (SPI1BUF)
0x0226 (U1RXREG)
—
0x0300 (ADC1BUF0)
0x0236 (U2RXREG)
—
0x0268 (SPI2BUF)
0x0440 (C1RXD)
0x0608 (PMDIN1)
—
—
—
DMAxPAD Register
Values to Write to
Peripheral
—
—
0x0182 (OC1R)
0x0180 (OC1RS)
—
0x0188 (OC2R)
0x0186 (OC2RS)
—
—
0x0248 (SPI1BUF)
—
0x0224 (U1TXREG)
—
—
0x0234 (U2TXREG)
0x0268 (SPI2BUF)
—
0x0608 (PMDIN1)
0x0442 (C1TXD)
0x3F6 (DAC1RDAT)
0x03F8 (DAC1LDAT)
© 2011 Microchip Technology Inc.
DS70291E-page 133