ST18952 datasheet(23/67 Pages) STMICROELECTRONICS

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ST18952

7.2

DMA registers

Address registers

Two 16-bit registers (unsigned) are dedicated per channel for address transfer:

• DIA: initial address. Contains the initial address of the selected address bus

(see DBC-bit of DGC register).

• DCA: current address. Contains the value to be transferred to the selected

address bus (see DBC-bit of DGC register) during the next transfer. The

different DCA values are:

Note:

See ”DAIC: Address/interrupt control register” on page 24 for DAI and DLA definitions

Counting registers

Two 16-bit registers (unsigned) per channel are dedicated for count transfer.

For a transfer of an N data block, DIC and DCC registers have to be loaded with N-1.

When DCC content is 0 (valid transfer count), it is loaded with DIC content for the next transfer.

• DIC: initial count. Contains the total number of transfers of the entire block

• DCC: current count. Contains the remaining number of transfers required to fill

the entire block. It is decremented after each transfer. The DCC values are:

Control registers

Three 16-bit control registers are dedicated to the DMA controller interface. These are the

general control register, the address interrupt control register and the mask sensitivity control

Reset

DAI

DLA

DCC = 0

DCA(n+1)

XXX

DCA(n)

DCA(n) + 1

0110

DCA(n) + 1

0111

DIA

Reset

DCC = 0

DCA(n+1)

DCA(n) - 1

DIC

ST18952 Datasheet(PDF) 23 Page - STMicroelectronics