Table 24 - Dma Transfer Timing Selections (Dma 0) - Nintendo GAME BOY ADVANCE Programming Manual

94
DMA0CNT_H [d13 - 12] DMA Startup Timing
The timing of the DMA transfer can be selected from the following options.

Table 24 - DMA Transfer Timing Selections (DMA 0)

Setting
00
01
10
11
DMA0CNT_H [d10] DMA Transfer Type
Sets the bit length of the transfer data.
With a setting of 0, the data are transferred by DMA in 16-bit (half-word) units. With a setting of 1, the
data are transferred by DMA in 32-bit (word) units.
DMA0CNT_H [d09] DMA Repeat
With the DMA repeat function set to ON, if V-blanking or H-blanking intervals are selected as the tim ing
of DMA startup, DMA is restarted when the next startup condition occurs (a V-blank or H-blank).
In this mode, restarting will continue as long as the DMA enable flag is not set to 0.
Note:
When the DMA repeat function is set to OFF, DMA halts as soon as the amount of data specified by
the value in the word-count register has been transferred.
DMA0CNT_H [d08] Source Address Control Flag
Control of the source address is specified after each DMA transfer.
A setting of 00 causes an increment.
A setting of 01 causes a decrement.
A setting of 10 causes it to be fixed.
11 is a prohibited code.
AGB-06-0001-002-B13
Released: May 27, 2005
Game Boy Advance Programming Manual
DMA Startup Timing
Start immediately
Start during a V-blanking interval
Starts at the beginning of a V-blanking interval (approximately 4.993
ms).
Start during a H-blanking interval
Starts at the beginning of a H-blanking interval (approximately 16.212
s).
µ
If this accompanies OAM access, the H-blanking interval must first be
freed of OBJ display hardware processing periods. (See
System" on page 19.)
Prohibited Code
May 25, 2005
"5 Image
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