Nintendo 1504166 Programming Manual - Page 115

Start Immediately, Start During a V-blanking interval, Start When Request Generated by Direct-Sound

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AGB Programming Manual DMA Transfer DMA(1,2)CNT_H [d14] Interrupt Request Enable Flag Enables an interrupt request to be generated when DMA transfer of the specified word count has been completed. No request is generated with a setting of 0; a request is generated with a setting of 1. DMA(1,2)CNT_H [d13 - 12] DMA Startup Timing The timing of the DMA transfer can be selected from the following options. Setting 00 01 10 11 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 µs). If this accompanies OAM access, the H-blanking interval must first be freed of OBJ display hardware processing periods. (See "Chapter 5, Image System".) Start When Request Generated by Direct-Sound FIFO Starts when a request is received form direct-sound FIFO. Specify sound FIFO as the destination address. Also, set the DMA repeat function [d09] to ON. DMA(1,2)CNT_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. In direct-sound FIFO transfer mode, the data are transferred in 32-bit units. ©1999 - 2001 Nintendo of America Inc. 115 D.C.N. AGB-06-0001-002B4

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AGB Programming Manual
DMA Transfer
©1999 - 2001 Nintendo of America Inc.
115
D.C.N. AGB-06-0001-002B4
DMA(1,2)CNT_H [d14] Interrupt Request Enable Flag
Enables an interrupt request to be generated when DMA transfer of the
specified word count has been completed.
No request is generated with a setting of 0; a request is generated with a
setting of 1.
DMA(1,2)CNT_H [d13 - 12] DMA Startup Timing
The timing of the DMA transfer can be selected from the following options.
Setting
DMA Startup Timing
00
Start Immediately
01
Start During a V-blanking interval
Starts at the beginning of a V-blanking interval (approximately
4.993 ms).
10
Start During a H-blanking interval
Starts at the beginning of a H-blanking interval (approximately
16.212
μ
s).
If this accompanies OAM access, the H-blanking interval must
first be freed of OBJ display hardware processing periods. (See
“Chapter 5, Image System”.)
11
Start When Request Generated by Direct-Sound
FIFO
Starts when a request is received form direct-sound
FIFO.
Specify sound FIFO as the destination address.
Also, set the DMA repeat function [d09] to ON.
DMA(1,2)CNT_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.
In direct-sound FIFO transfer mode, the data are transferred in 32-bit units.