Pinout
| Pin | Name | Direction | Description |
|---|---|---|---|
| 0 | IRQ? | Output | Always wired to GND inside game cartridge; Possibly used for interrupt signaling |
| 1 | RCLK | Output | Return clock; Game cartridge sends back CLK signal delayed by a few ns |
| 2 | CLK | Input | Clock, 25MHz |
| 3 | CS | Input | Chip select; Switch pulls this LOW during a transfer |
| 4 | DAT0 | Inout | Data bus pin 0 |
| 5 | DAT1 | Inout | Data bus pin 1 |
| 6 | VCC 3.3v | Input | |
| 7 | DAT2 | Inout | Data bus pin 2 |
| 8 | DAT3 | Inout | Data bus pin 3 |
| 9 | VCC 1.8v | Input | |
| 10 | DAT4 | Inout | Data bus pin 4 |
| 11 | DAT5 | Inout | Data bus pin 5 |
| 12 | DAT6 | Inout | Data bus pin 6 |
| 13 | DAT7 | Inout | Data bus pin 7 |
| 14 | GND | ||
| 15 | RST | Input | Reset, active LOW. |
All IO use 1.8V for logic HIGH and 0V for logic LOW.
Protocol
Switch game cartridges use a simple (but Nintendo proprietery) SPI-like bus with 8-bit width (DAT7..0). It is very similar to the bus interface of 3DS game cartridges, except with very different commands.
The Switch host starts a transfer by first pulling CS low, followed by clocking a byte each clock cycle. The bus data will always be ready before the rising edge of the CLK signal, so that it can be captured on the rising edge. After command bytes are written to the bus, the direction of the bus implicitly changes and the game cartridge responds. The Switch host keeps clocking while the game cartridge responds. After the transfer is ended, the CS line is pulled high again.
Commands are 16 bytes long, and followed immediately by a 4-byte CRC-32 over the command bytes. After this, the Switch stops driving the data bus, and the bus will be 'floating'. Due to the pull-ups on the bus, it will slowly converge to logic HIGH state. The Switch will clock 2 cycles to allow the bus to settle a direction change. The Switch host will then clock another cycle and if the game cartridge didn't receive the CRC OK, it will respond with "01". Otherwise it will respond with "00" and pull DAT0 low on the next cycle to signal it is busy. The Switch host will then keep clocking until the cartridge is ready.
When the game cartridge is ready to send the actual data response, it will pull the DAT0 pin high for 2 cycles to let the Switch host know. After this, the game cartridge will send the actual data response bytes.
The actual response bytes are also followed immediately by a 4-byte CRC-32 over the actual data response bytes.
Commands
A typical boot up sequence of a game cartridge (in this case, the game "1,2 Switch") looks like this:
| Command | Size | Description |
|---|---|---|
5B000000000000010000000000000000
|
0x200 | Read sector 0, contains "HEAD" blob |
5B000000000000010000000000000000
|
0x200 | Read sector 0, contains "HEAD" blob |
56000000000000000000000000000000
|
0x4 | Read card id "AE F8 01 21" |
28000000000000000000000000000000
|
0x4 | ReadĀ ??? "02 00 00 00" |
A5000000000000000000000000000000
|
0x4 | ReadĀ ??? "00 00 00 00" |
56000000000000000000000000000000
|
0x4 | Read card id "AE F8 01 21" |
28000000000000000000000000000000
|
0x4 | ReadĀ ??? "02 00 00 00" |
5B000000380000010000000000000000
|
0x200 | Read sector 0x38, contains "CERT" blob |
E2000000000000000000000000000000
|
0x4 | ReadĀ ??? "01 00 00 00" |
E0000000000000000000000000000000
|
0x200 | Read crypto-challenge header |
200838A25A344F818ABB6456694D4E8D
|
0 | Enter crypto mode with seed "0838A25A344F818ABB6456694D4E8D" |
7EE41FDF12C01C157CC899910673A0CF
|
0x40 | Encrypted command, possibly read UID? |
263C8230EC15FAE3CE79365BD850F4BD
|
0x0 | Encrypted command |
B6FDA6F37FFA29E18831D0B217DFBDBE
|
0x4 | Encrypted command, possibly read card id? |
7B97F7DF07240AA9870E1C974336FA8A
|
0x4 | Encrypted command |
The meaning of some these commands are currently unknown.
Observations
- The entire game cartridge contents can be dumped using the plaintext 5B commands (including "update" and "normal" partitions) except for the "secure" partition which can only be read from encrypted mode.
Encryption
After a few initial plaintext commands, the Switch instructs the game cartridge to enter into encrypted mode. From that point on, commands and responses are sent encrypted over the bus. The encryption algorithm used is currently unknown.
Manufacturers
- Macronix (MX)
- Uses package: LGA
- Uses card id: 0xC2
- OKI Semiconductor
- Uses package: TSOP-48
- Uses card id: 0xAE
- SanDisk?
- Uses package:Ā ??
- Uses card id: 0x45Ā ?
Examples
The following examples are extracted from the game "1,2 Switch".
HEAD blob
00000000: 6c dc 15 86 fa 88 11 f6 2f 4c b0 b8 3d 3f e9 63 l......./L..=?.c 00000010: e9 5d b7 41 80 d5 1d e4 99 fa 5b 17 8a f1 91 e4 .].A......[..... 00000020: d0 4c de 68 c5 d7 57 64 b5 91 fd 68 36 f3 fe ce .L.h..Wd...h6... 00000030: c9 d1 fa 8e 9d ce 94 c2 55 a3 7a 60 f9 80 85 a8 ........U.z`.... 00000040: 44 18 a9 b3 29 20 42 8d 5f 7a 2f ae 50 81 46 9c D...) B._z/.P.F. 00000050: 81 a1 a0 e2 89 3a 46 37 19 c1 c6 11 07 f9 f8 74 .....:F7.......t 00000060: 89 98 d0 96 8e 44 10 f7 ac 62 f6 4a 50 b9 3d dc .....D...b.JP.=. 00000070: c9 cd 62 20 df 44 c7 41 d1 50 49 3c 06 38 dd 52 ..b .D.A.PI<.8.R 00000080: f2 84 bb 9f 63 e7 64 4f b9 db 7f a2 47 e2 2f 3c ....c.dO....G./< 00000090: ba 52 27 92 6d 17 e4 25 a6 90 99 d6 88 66 3a c1 .R'.m..%.....f:. 000000a0: 52 54 6a c6 79 09 42 3c 3f 9e 33 32 f4 c6 eb 7d RTj.y.B<?.32...} 000000b0: 60 e5 f9 44 8b 6e ff 43 a6 13 6c 29 8e bd c8 6b `..D.n.C..l)...k 000000c0: 64 39 2d d5 f3 9a 4b 04 89 dc ac 0b b4 22 35 9f d9-...K......"5. 000000d0: df 74 2f f0 fb 6d a6 a4 56 ff 92 88 72 42 72 ea .t/..m..V...rBr. 000000e0: de f8 37 0e 46 77 04 05 43 df 59 2f 92 d1 3c 38 ..7.Fw..C.Y/..<8 000000f0: 73 c8 64 e5 ea 2b 96 56 85 d2 9d a6 3a c4 46 1a s.d..+.V....:.F. 00000100: 48 45 41 44 40 02 0c 00 ff ff ff ff 00 f8 00 00 HEAD@........... 00000110: 44 6c dd 95 4e c0 45 02 f1 27 38 00 00 00 00 00 Dl..N.E..'8..... 00000120: 08 5a 9c f5 ab 2a 9d f5 da 96 ab 8e 7a e9 11 68 .Z...*......z..h 00000130: 00 f0 00 00 00 00 00 00 00 02 00 00 00 00 00 00 ................ 00000140: 11 f7 72 54 a1 85 c0 cf 14 e9 99 f0 6a 1f c0 61 ..rT........j..a 00000150: 05 74 33 f0 50 3e ee 78 68 7e f5 ef 33 da f1 1f .t3.P>.xh~..3... 00000160: 88 7f 7c a9 85 bd 0f 4e 2f fe cd 1f f4 26 74 29 ..|....N/....&t) 00000170: 49 9d e5 d6 df c4 75 03 b9 9a b9 c7 8f 37 5c 88 I.....u......7\. 00000180: 01 00 00 00 02 00 00 00 00 00 00 00 40 02 0c 00 ............@... 00000190: ea a4 81 b6 30 4b 45 0c 71 5f a3 0c 5f 88 1f 9a ....0KE.q_.._... 000001a0: 67 9a e6 29 15 50 1a 46 98 a5 a1 af b1 07 ed 48 g..).P.F.......H 000001b0: df a8 36 bb cd 2d d7 ba f5 c6 80 0a 03 ff 1f 73 ..6..-.........s 000001c0: 2c bd 18 38 a0 49 24 c7 49 d1 94 52 ef 6a 7c 23 ,..8.I$.I..R.j|# 000001d0: eb ca a4 35 52 59 e6 d3 98 ed b7 ec 11 cf 0b 1d ...5RY.......... 000001e0: 29 f1 1d 43 e8 e0 2e 0f db 98 1a 88 47 fa 11 79 )..C........G..y 000001f0: a8 ef 47 21 a1 bb de a6 dd b4 d6 27 8f 25 62 e4 ..G!.......'.%b.
CERT blob
00000000: 72 cf 8c ed ce ed 43 fb 82 77 2c 86 2e da 1d 07 r.....C..w,.....
00000010: 13 68 2e 1a fe 15 ac 6e 27 21 ec 3a 0f e9 fa 20 .h.....n'!.:...
00000020: 7b 70 62 a4 c3 47 65 86 ca 73 08 f0 71 80 17 59 {pb..Ge..s..q..Y
00000030: 6a c8 2e e9 42 f8 69 12 7c 9d 5d 02 24 6b 2b 5e j...B.i.|.].$k+^
00000040: c4 d2 c8 80 11 47 a2 5e 41 b3 a9 41 95 91 bd 8f .....G.^A..A....
00000050: 6b c1 f5 0b 9b 37 06 6b ea 8e cd e9 eb 1d 8e c7 k....7.k........
00000060: 3e 83 f1 85 8b 85 c6 af bf 38 c1 0a 7c c0 d1 42 >........8..|..B
00000070: 0c 0c 7c 22 cd 0f a3 8c ee 48 e5 32 9f 68 1c e5 ..|".....H.2.h..
00000080: 13 4b d7 94 a1 c8 18 d0 1f 11 de 35 1e 34 a7 d1 .K.........5.4..
00000090: 32 d8 d8 66 8b b1 db 1a 5b b6 1f fd 9a c9 a4 4b 2..f....[......K
000000a0: 66 61 d9 52 5c f1 3c 8d de 25 f1 76 06 1b f2 37 fa.R\.<..%.v...7
000000b0: a7 fb 1c f5 b8 20 67 ff 79 f2 a4 ab 8a 82 c4 97 ..... g.y.......
000000c0: 9d 4c 01 e7 18 1f 91 60 f7 b8 68 da 73 b3 fa 47 .L.....`..h.s..G
000000d0: 18 8f e8 ca e9 4b 08 1b 13 3e 17 e2 63 99 95 2f .....K...>..c../
000000e0: e6 d1 98 dc 50 77 7c 8a 25 eb 9e 34 0d e5 f1 93 ....Pw|.%..4....
000000f0: b2 32 c5 da a1 ff 53 12 fb 5d bd 1f 67 6e 94 84 .2....S..]..gn..
00000100: 43 45 52 54 00 00 00 00 00 00 00 00 00 00 00 00 CERT............
00000110: 87 cd 3f 5c 04 49 6a 02 5f b1 7a 6a 13 d1 88 8f ..?\.Ij._.zj....
00000120: 00 10 00 00 00 00 00 00 00 00 09 52 b7 d5 d2 30 ...........R...0
00000130: a3 13 4d 94 4b 0f 87 fe 2b da 37 ef 2d 38 25 75 ..M.K...+.7.-8%u
00000140: d6 3e 94 7c 2a a0 f6 8a a3 60 40 18 5f 53 54 53 .>.|*....`@._STS
00000150: fc 0f 1c 2d 10 92 f8 b6 d2 f2 97 df b2 13 2a 14 ...-..........*.
00000160: ea c4 b1 9f 9c f4 b8 2f ef 5b 4f e3 8e d9 47 d7 ......./.[O...G.
00000170: 2c 15 95 68 7e f4 e0 71 99 83 17 0c e1 fe 84 b5 ,..h~..q........
00000180: a1 30 4c 33 c6 2c 13 fa 19 4d 37 48 e9 4e 3b a6 .0L3.,...M7H.N;.
00000190: fa 0a 1e 13 46 f1 bf 15 88 5d 59 65 f7 a4 ad ba ....F....]Ye....
000001a0: d6 12 ce c2 33 b8 c3 c9 8f d3 34 c6 a5 6d 52 ff ....3.....4..mR.
000001b0: d9 55 96 5f cd 59 d5 0d 84 ff 83 7d f0 33 d8 32 .U._.Y.....}.3.2
000001c0: ed 35 48 62 3a 68 2f 1e bf 22 1c fb cd e5 d9 b8 .5Hb:h/.."......
000001d0: fc 24 e1 58 5d b3 4d 69 60 ab 8d 0e 17 28 24 43 .$.X].Mi`....($C
000001e0: b7 a6 43 99 03 3c 1a 92 09 6b 8c 6f 09 37 6a 50 ..C..<...k.o.7jP
000001f0: 46 91 d1 bf 7d 7a 32 a9 70 28 f1 5e 31 97 ac be F...}z2.p(.^1...
Crypto-challenge header
00000000: 44 6c dd 95 4e c0 45 02 00 00 00 00 00 00 00 00 Dl..N.E......... 00000010: a0 27 b4 2d 32 91 a0 8f 06 10 cb b0 ff d1 1b b3 .'.-2........... 00000020: aa 8a 9e 34 05 e0 81 42 4a 50 88 fc 5c 06 c6 c4 ...4...BJP..\... 00000030: 5c 54 10 ee 66 07 0c a5 04 9f ef 9a 00 00 00 00 \T..f........... 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................