Panasonic MN101C77C - Manual (Page 440)

Chapter 14 Automatic Transfer Controller
XIV - 2 Overview
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.