at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 331

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

25. Peripheral DMA Controller (PDC)
25.1
6249D–ATARM–20-Dec-07
Description
The Peripheral DMA Controller (PDC) transfers data between on-chip serial peripherals and the
on- and/or off-chip memories. The link between the PDC and a serial peripheral is operated by
the AHB to ABP bridge.
The PDC contains twenty channels. The full-duplex peripherals feature eighteen mono-direc-
tional channels used in pairs (transmit only or receive only). The half-duplex peripherals feature
two bi-directional channels.
The user interface of each PDC channel is integrated into the user interface of the peripheral it
serves. The user interface of mono directional channels (receive only or transmit only), contains
two 32-bit memory pointers and two 16-bit counters, one set (pointer, counter) for current trans-
fer and one set (pointer, counter) for next transfer. The bi-directional channel user interface
contains four 32-bit memory pointers and four 16-bit counters. Each set (pointer, counter) is
used by current transmit, next transmit, current receive and next receive.
Using the PDC removes processor overhead by reducing its intervention during the transfer.
This significantly reduces the number of clock cycles required for a data transfer, which
improves microcontroller performance.
To launch a transfer, the peripheral triggers its associated PDC channels by using transmit and
receive signals. When the programmed data is transferred, an end of transfer interrupt is gener-
ated by the peripheral itself.
AT91SAM9263 Preliminary
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