Table of Contents
Advertisement
CHAPTER 16 DMA CONTROLLER (DMAC)
16.1
Overview of the DMA Controller (DMAC)
The DMA controller (DMAC) is a module that implements DMA (Direct Memory Access)
transfer on FR family devices. When this module is used to control DMA transfer,
various kinds of data can be transferred at high speed by bypassing the CPU,
enhancing system performance.
The external transfer request pins are connected to DMA transfer requests at end points
1 and 2 of the USB function inside the chip.
■ Hardware Configuration
The DMA controller (DMAC) consists mainly of the following blocks:
•
Five independent DMA channels
•
5-channel independent access control circuit
•
32-bit address registers (reload specifiable, two registers for each channel)
•
16-bit rotation count register (reload specifiable, one register for each channel)
•
4-bit block rotation register (one for each channel)
•
External transfer request input pins: DREQ0, DREQ1, and DREQ2 (for ch0, ch1, and ch2
•
External transfer request acceptance output pins: DACK0, DACK1, and DACK2 (for ch0, ch1,
•
DMA end output pins: DEOP0, DEOP1, and DEOP2 (for ch0, ch1, and ch2 only)
•
Fly-by transfer (memory to I/O and I/O to memory) (for ch0, ch1, and ch2 only)
•
2-cycle transfer
■ Main Functions
The following are the main functions related to data transfer by the DMA controller (DMAC):
•
Data can be transferred independently over multiple channels (5 channels)
•
Priority (ch.0>ch.1>ch.2>ch.3>ch.4)
•
The priority can be rotated between ch.0 and ch.1.
•
DMAC start sources
•
External dedicated pin input (edge detection/level detection for ch0, ch1, and ch2 only)
•
Built-in peripheral requests (shared interrupt requests, including external interrupts)
•
Software request (register write)
•
Transfer mode
•
Demand transfer, burst transfer, step transfer, and block transfer
•
Addressing mode: 32-bit full addressing (increment/decrement/fixed)
•
The address increment/decrement range is from -255 to plus 255.
•
Data types: Byte, halfword, and word length
•
Single shot/reload selectable
320
only)
and ch2 only)
Advertisement
Table of Contents
