Difference between revisions of "SPI Registers"
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− | | Timeout (Tries = 31<< | + | | Timeout (Tries = 31<<Clock (from [[#NSPI_CNT|NSPI_CNT]]) + Timeout) |
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| 24-26 | | 24-26 |
Revision as of 21:52, 11 May 2019
Registers
Old3DS | Name | Address | Width | Used by |
---|---|---|---|---|
Yes | SPI_CNT1 | 0x10142000 | 2 | |
Yes | SPI_DATA1 | 0x10142002 | 1 | |
Yes | NSPI_CNT1 | 0x10142800 | 4 | |
Yes | NSPI_DONE1 | 0x10142804 | 4 | |
Yes | NSPI_BLKLEN1 | 0x10142808 | 4 | |
Yes | NSPI_FIFO1 | 0x1014280C | 4 | |
Yes | NSPI_STATUS1 | 0x10142810 | 4 | |
Yes | NSPI_AUTOPOLL1 | 0x10142814 | 4 | - |
Yes | NSPI_INT_MASK1 | 0x10142818 | 4 | - |
Yes | NSPI_INT_STAT1 | 0x1014281C | 4 | - |
Yes | SPI_CNT2 | 0x10143000 | 2 | |
Yes | SPI_DATA2 | 0x10143002 | 1 | |
Yes | NSPI_CNT2 | 0x10143800 | 4 | |
Yes | NSPI_DONE2 | 0x10143804 | 4 | |
Yes | NSPI_BLKLEN2 | 0x10143808 | 4 | |
Yes | NSPI_FIFO2 | 0x1014380C | 4 | |
Yes | NSPI_STATUS2 | 0x10143810 | 4 | |
Yes | NSPI_AUTOPOLL2 | 0x10143814 | 4 | - |
Yes | NSPI_INT_MASK2 | 0x10143818 | 4 | - |
Yes | NSPI_INT_STAT2 | 0x1014381C | 4 | - |
Yes | SPI_CNT3 | 0x10160000 | 2 | |
Yes | SPI_DATA3 | 0x10160002 | 1 | |
Yes | NSPI_CNT3 | 0x10160800 | 4 | |
Yes | NSPI_DONE3 | 0x10160804 | 4 | |
Yes | NSPI_BLKLEN3 | 0x10160808 | 4 | |
Yes | NSPI_FIFO3 | 0x1016080C | 4 | |
Yes | NSPI_STATUS3 | 0x10160810 | 4 | |
Yes | NSPI_AUTOPOLL3 | 0x10160814 | 4 | - |
Yes | NSPI_INT_MASK3 | 0x10160818 | 4 | - |
Yes | NSPI_INT_STAT3 | 0x1016081C | 4 | - |
There are two register interfaces: the old NDS/DSi one and an alternative faster interface introduced with the 3DS.
To toggle between those interfaces, use the CFG11_SPI_CNT register.
SPI_CNT
This is the old NDS/DSi SPI interface.
Bits | Name |
---|---|
0-1 | Baudrate (0=4MHz, 1=2MHz, 2=1MHz, 3=512KHz) |
2-6 | This was added with 3DS. |
7 | Busy Flag (0=Ready, 1=Busy) (presumably Read-only) |
8-9 | Device Select (0=Powerman., 1=Firmware, 2=Touchscreen) |
10 | Transfer Size (0=8bit/Normal, 1=16bit/Bugged) |
11 | Chipselect Hold (0=Deselect after transfer, 1=Keep selected) |
12-13 | Not used (Zero) |
14 | Interrupt Request (0=Disable, 1=Enable) |
15 | SPI Bus Enable (0=Disable, 1=Enable) |
NSPI_CNT
This is an alternative faster interface introduced with the 3DS.
Bits | Name |
---|---|
0-2 | Clock |
6-7 | Device select |
12 | Bus mode (0 = 1 bit, 1 = 4 bit) |
13 | Transfer direction (0 = read, 1 = write) |
15 | 1 = Busy/enable |
Device id | Bus | Device select | Clock |
---|---|---|---|
0 | 3 | 0 | 2 |
1, 2 | 3 | 1, 2 | ?, ? |
3 | 1 | 0 | 5 |
4, 5 | 1 | 1, 2 | ?, ? |
6 | 2 | 0 | ? |
NSPI_DONE
BIT | DESCRIPTION |
---|---|
0 | Chip select |
1-31 | Unused |
Contains 1 when the SPI slave is selected. A 0 is written here on transfer end to deselect the slave.
NSPI_BLKLEN
BIT | DESCRIPTION |
---|---|
0-20 | Transfer size |
21-31 | Unused |
The number of bytes to be sent/read is written to this register.
NSPI_FIFO
BIT | DESCRIPTION |
---|---|
0-31 | Data |
32-bit FIFO for reading/writing the SPI payload.
NSPI_STATUS
BIT | DESCRIPTION |
---|---|
0 | FIFO full (0 = not full, 1 = full) |
1-31 | Unused |
At transfer start and every 32 bytes the FIFO becomes busy.
NSPI_AUTOPOLL
BIT | DESCRIPTION |
---|---|
0-7 | Command |
16-19 | Timeout (Tries = 31<<Clock (from NSPI_CNT) + Timeout) |
24-26 | Bit offset (0-7) |
30 | Poll for a set or unset bit |
31 | 1 = Enable/Busy |
This automatically sends a command to the device and compares the specified bit in the response with bit 30 until it matches or a timeout occurs.
NSPI_INT_MASK
BIT | DESCRIPTION |
---|---|
0 | Transfer finished? (1 = disabled) |
1 | Autopoll success (1 = disabled) |
2 | Autopoll timeout (1 = disabled) |
NSPI_INT_STAT
BIT | DESCRIPTION |
---|---|
0 | Transfer finished? |
1 | Autopoll success |
2 | Autopoll timeout |
Interrupt ID 0x56 or 0x57 (depending on the bus) is fired when any of the bits change to 1 except for interrupts masked in NSPI_INT_MASK. Writing 1 to a bit in this register aknowledges the interrupt.