The Joy-Cons use bluetooth or a wired connection to communicate with the console, depending if they are physically connected to it or not.
dekuNukem has started RE on the protocols used [1].
Firmware
The firmware of the Joy-Cons seems to be generic across all instances. Details such as the handedness of the controller and the color is just indicated in a configuration part of the flash. Judging by quick glance at the firmware, it's probably identical to that used on the Pro Controller as well.
| Controller | 1.0.0 |
|---|---|
| Joy-Con Left (Blue) | flash dump |
| Joy-Con Right (Red) | flash dump |
The flash is in a patch-ram format. Tools for dealing with it are available [2]. A dump of the ROM region (taken while firmware was running) can be found here. Note this is the same SoC used on the other controller models, as well.
Left & Right Separate Joy-con
When paired directly to a computer over bluetooth, the joy-con both provide identical HID input report descriptor. This does not appear to include motion controls, IR data, or NFC. They both behave as detached single-player controllers.
HID Input Report Descriptor (Hexadecimal):
00000000: 05010905 A1010601 FF852109 21750895 ....¡...ÿ…!.!u.• 00000010: 30810285 30093075 08953081 02853109 0..…0.0u.•0..…1. 00000020: 31750896 69018102 85320932 75089669 1u.–i...…2.2u.–i 00000030: 01810285 33093375 08966901 8102853F ...…3.3u.–i...…? 00000040: 05091901 29101500 25017501 95108102 ....)...%.u.•... 00000050: 05010939 15002507 75049501 81420509 ...9..%.u.•..B.. 00000060: 75049501 81010501 09300931 09330934 u.•......0.1.3.4 00000070: 16000027 FFFF0000 75109504 81020601 ...'ÿÿ..u.•..... 00000080: FF850109 01750895 30910285 10091075 ÿ…...u.•0‘.…...u 00000090: 08953091 02851109 11750895 30910285 .•0‘.…...u.•0‘.… 000000A0: 12091275 08953091 02C0 ...u.•0‘.À
| Parsed Bytes | Description |
|---|---|
| 0x05, 0x01, | Usage Page (Generic Desktop Ctrls) |
| 0x09, 0x05, | Usage (Game Pad) |
| 0xA1, 0x01, | Collection (Application) |
| 0x06, 0x01, 0xFF, | Usage Page (Vendor Defined 0xFF01) |
| 0x85, 0x21, | Report ID (33) |
| 0x09, 0x21, | Usage (0x21) |
| 0x75, 0x08, | Report Size (8) |
| 0x95, 0x30, | Report Count (48) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x85, 0x30, | Report ID (48) |
| 0x09, 0x30, | Usage (0x30) |
| 0x75, 0x08, | Report Size (8) |
| 0x95, 0x30, | Report Count (48) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x85, 0x31, | Report ID (49) |
| 0x09, 0x31, | Usage (0x31) |
| 0x75, 0x08, | Report Size (8) |
| 0x96, 0x69, 0x01, | Report Count (361) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x85, 0x32, | Report ID (50) |
| 0x09, 0x32, | Usage (0x32) |
| 0x75, 0x08, | Report Size (8) |
| 0x96, 0x69, 0x01, | Report Count (361) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x85, 0x33, | Report ID (51) |
| 0x09, 0x33, | Usage (0x33) |
| 0x75, 0x08, | Report Size (8) |
| 0x96, 0x69, 0x01, | Report Count (361) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x85, 0x3F, | Report ID (63) |
| 0x05, 0x09, | Usage Page (Button) |
| 0x19, 0x01, | Usage Minimum (0x01) |
| 0x29, 0x10, | Usage Maximum (0x10) |
| 0x15, 0x00, | Logical Minimum (0) |
| 0x25, 0x01, | Logical Maximum (1) |
| 0x75, 0x01, | Report Size (1) |
| 0x95, 0x10, | Report Count (16) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x05, 0x01, | Usage Page (Generic Desktop Ctrls) |
| 0x09, 0x39, | Usage (Hat switch) |
| 0x15, 0x00, | Logical Minimum (0) |
| 0x25, 0x07, | Logical Maximum (7) |
| 0x75, 0x04, | Report Size (4) |
| 0x95, 0x01, | Report Count (1) |
| 0x81, 0x42, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,Null State) |
| 0x05, 0x09, | Usage Page (Button) |
| 0x75, 0x04, | Report Size (4) |
| 0x95, 0x01, | Report Count (1) |
| 0x81, 0x01, | Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x05, 0x01, | Usage Page (Generic Desktop Ctrls) |
| 0x09, 0x30, | Usage (X) |
| 0x09, 0x31, | Usage (Y) |
| 0x09, 0x33, | Usage (Rx) |
| 0x09, 0x34, | Usage (Ry) |
| 0x16, 0x00, 0x00, | Logical Minimum (0) |
| 0x27, 0xFF, 0xFF, 0x00, 0x00, | Logical Maximum (65534) |
| 0x75, 0x10, | Report Size (16) |
| 0x95, 0x04, | Report Count (4) |
| 0x81, 0x02, | Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) |
| 0x06, 0x01, 0xFF, | Usage Page (Vendor Defined 0xFF01) |
| 0x85, 0x01, | Report ID (1) |
| 0x09, 0x01, | Usage (0x01) |
| 0x75, 0x08, | Report Size (8) |
| 0x95, 0x30, | Report Count (48) |
| 0x91, 0x02, | Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) |
| 0x85, 0x10, | Report ID (16) |
| 0x09, 0x10, | Usage (0x10) |
| 0x75, 0x08, | Report Size (8) |
| 0x95, 0x30, | Report Count (48) |
| 0x91, 0x02, | Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) |
| 0x85, 0x11, | Report ID (17) |
| 0x09, 0x11, | Usage (0x11) |
| 0x75, 0x08, | Report Size (8) |
| 0x95, 0x30, | Report Count (48) |
| 0x91, 0x02, | Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) |
| 0x85, 0x12, | Report ID (18) |
| 0x09, 0x12, | Usage (0x12) |
| 0x75, 0x08, | Report Size (8) |
| 0x95, 0x30, | Report Count (48) |
| 0x91, 0x02, | Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) |
| 0xC0, | End Collection |
Colors
HEX codes for the colors shown in the "Controllers" menu of the Switch UI can be found in a Joy-con SPI dump starting at offset 0x6050. Body color is first followed by button color and each is 3 bytes long. These values are able to be re-written with any HEX color value to make the Joy-cons show up as different colors in the UI. The following is a list of official HEX colors recovered from SPI dumps.
| Color Name | Body HEX | Button HEX |
|---|---|---|
| Gray | #828282 | #0F0F0F |
| Neon Red | #FF3C28 | #1E0A0A |
| Neon Blue | #0AB9E6 | #001E1E |
| Neon Yellow | #E6FF00 | #142800 |
| Neon Green | #1EDC00 | #002800 |
| Neon Pink | #FF3278 | #28001E |
| Mario Red | #E10F00 | #280A0A |