M32CSLASH8A datasheet(137/372 Pages) RENESAS

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M32C/8A Group

13. DMAC

Rev.1.00

Jul 15, 2007

Page 120 of 352

REJ09B0385-0100

13. DMAC

DMAC allows data to be sent to and from memory without involving the CPU. The M32C/8A Group has four DMAC

channels. DMAC transfers a 8- or 16-bit data from a source address to a destination address for each transfer request.

DMA0 and DMA1 must be prioritized when using DMAC. DMA2 and DMA3 share the registers with the high-speed

interrupts. The high-speed interrupts cannot be used when three or more DMAC channels are used.

The CPU and DMAC use the same data bus, but DMAC has a higher bus access privilege than the CPU. DMAC

employing the cycle-steal method enables a high-speed operation from a transfer request to a completion of 16-bit

(word) or 8-bit (byte) data transfer.

Figure 13.1 shows a mapping of DMAC-associated registers. Table 13.1 lists specifications of DMAC. Figures 13.2

to 13.6 show DMAC-associated registers. Figures 13.7 and 13.8 show register settings.

Because the registers shown in Figure 13.1 are allocated in the CPU, use the LDC instruction to set the registers.

To set registers DCT2, DCT3, DRC2, DRC3, DMA2, and DMA3, set the B flag to 1 (register bank 1) and write to

registers R0 to R3, A0, and A1 with the MOV instruction.

To set registers DSA2 and DSA3, set the B flag to 1 and write to registers SB and FB with the LDC instruction.

To set registers DRA2 and DRA3, write to registers SVP and VCT with the LDC instruction.

Figure 13.1

DMA mode register 0

DMA mode register 1

DMA0 transfer count register

DMA1 transfer count register

DMA0 transfer count reload register(1)

DMA1 transfer count reload register(1)

DMA0 memory address register

DMA1 memory address register

DMA0 SFR Address register

DMA1 SFR Address register

DMA0 memory address reload register(1)

DMA1 memory address reload register(1)

DMAC-Associated Registers

When three or more DMAC channels are used,

the register bank 1 is employed as DMAC registers.

DMA2 transfer count register

DMA3 transfer count register

DMA2 memory address register

DMA3 memory address register

DMA2 SFR Address register

DMA3 SFR Address register

DMA2 transfer count reload register(1)

DMA3 transfer count reload register(1)

When three or more DMAC channels are used,

the high-speed interrupt registers are employed as DMAC

registers.

DCT0

DCT1

DRC0

DRC1

DMD0

DMD1

DMA2 memory address reload register(1)

DMA3 memory address reload register(1)

DRA2(SVP)

DRA3(VCT)

SVF

Flag save register

DMA0

DMA1

DSA0

DSA1

DRA0

DRA1

DMA2(A0)

DMA3(A1)

DSA2(SB)

DSA3(FB)

DCT2(R0)

DCT3(R1)

DRC2(R2)

DRC3(R3)

When using DMA2 and DMA3, use the CPU registers shown in

parentheses ( ).

NOTE:

1. These registers are used for repeat transfer, not for single transfer.

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