3DS NDMA has 8 channels. The first 0x100-bytes of this IO mem is mirrored at 0x10002100, repeated every 0x100-bytes until the end of the 0x1000-byte IO mem. NDMA can access the ARM9 bootrom, including the protected part before it is locked out.
Registers
NDMA_GLOBAL_CNT
| Bit
|
Description
|
| 0
|
Global enable?
|
| 19-16
|
Cycle selection.
|
| 31
|
DMA arbitration method. 0=Fixed method, 1=Round robin
|
NDMA_SRC_ADDR
| Bit
|
Description
|
| 31-0
|
Source data address. Must be multiple of 4.
|
Like old DMA, NDMA_SRC_ADDR is copied to internal registers when written to.
NDMA_DST_ADDR
| BIT
|
DESCRIPTION
|
| 31-0
|
Destination data address. Must be multiple of 4.
|
Like old DMA, NDMA_DST_ADDR is copied to internal registers when written to.
NDMA_TRANSFER_CNT
| Bit
|
Description
|
| 27-0
|
Total number of words transferred.
|
NDMA_WRITE_CNT
| Bit
|
Description
|
| 23-0
|
Number of words to transfer.
|
NDMA_BLOCK_CNT
| Bit
|
Description
|
| 15-0
|
Interval timer.
|
| 17-16
|
Prescaler. 0=System freq, 1=1/4th freq, 2=1/16th freq, 3=1/64th freq.
|
NDMA_FILL_DATA
| Bit
|
Description
|
| 31-0
|
Fill data.
|
NDMA_CNT
| Bit
|
Description
|
| 11-10
|
Destination address update method. 0=Increment, 1=Decrement, 2=Fixed.
|
| 12
|
Destination address reload flag.
|
| 14-13
|
Source address update method. 0=Increment, 1=Decrement, 2=Fixed, 3=No address (for filling)
|
| 15
|
Source address reload flag.
|
| 19-16
|
Block transfer word count = (1<<x) words.
|
| 27-24
|
Startup mode.
|
| 28
|
Immediate mode.
|
| 29
|
Repeating mode.
|
| 30
|
IRQ enable
|
| 31
|
Enable/busy flag.
|
Startup modes (27-24)
| Value
|
Description
|
| 0
|
TIMER0?
|
| 1
|
TIMER1?
|
| 2
|
TIMER2?
|
| 3
|
TIMER3?
|
| 4
|
CTRCARD0
|
| 5
|
CTRCARD1
|
| 6
|
?
|
| 7
|
EMMC
|
| 8
|
AES WD FREE
|
| 9
|
AES RD FREE
|
| 10
|
SHA
|
| 11
|
?
|
| 12
|
?
|
| 13
|
?
|
| 14
|
?
|
| 15
|
AES + SHA COMBINED?
|
Block transfers
First, a word is always 32 bits. Second, the block transfer specified in NDMA_CNT is the smallest atom of data that will be transferred in a burst. The bus is monopolized until this block is transferred, without splitting up.
The next block transfer will happen after the specified time in the NDMA_BLOCK_CNT interval timer, until done.
Immediate mode
Transfers the words specified in NDMA_WRITE_CNT immediately following block transfer rules. NDMA_TRANSFER_CNT and repeating mode are ignored.
Repeating mode
Transfers the words specified in NDMA_WRITE_CNT following the startup mode event. NDMA_TRANSFER_CNT is ignored.
No immediate and no repeating mode
Transfers the words specified in NDMA_WRITE_CNT for each startup event, and gets disabled when the total number of words in NDMA_TRANSFER_CNT are transferred.