Chapter 14 Automatic Transfer Controller

14-1 Overview

14-1-1 ATC1

This LSI contains an automatic transfer controller (ATC) that uses direct memory access (DMA) to transfer the contents of the whole memory space (256 KB) using the hardware. This ATC block is called ATC1.

ATC1 is activated by an interrupt or a flag set by the software. Once this occurs, even if it is in the middle of executing an instruction, the microcontroller waits for a time when it can release the bus, stops normal operation, and transfers bus control to ATC1. ATC1 then uses the released bus for the hardware data transfer.

The software sets the activation factor in ATC1 control register 1 (AT1CNT1), then data transfer begins when the AT1ACT flag in ATC1 control register 0 (AT1CNT0) is set to "1". AT1ACT flag is automatically cleared to "0" when ATC1 is activated.

The transfer data counter (AT1TRC) determines the number of transfers that ATC1 makes, up to a maximum of 255 times. There are also 16 transfer modes, set in ATC1 control register 0 (AT1CNT0).

The interrupt enable flag (xxxIE) for interrupt as a trigger factor needs not to be set. This is because the automatic data transfer occurs in the hardware without going through an inter- rupt service routine. If the interrupt enable flag (xxxIE) is set for the type of interrupt ATC1, a regular interrupt is generated after the automatic transfer ends.

XIV - 2 Overview

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Panasonic MN101C77C, F77G user manual Overview, 14-1-1 ATC1