Moshiboard

Moshiboard

The Moshiboard laser cutter board is a proprietary controller with proprietary software. In the case of Moshiboard this software is called `MoshiDraw`. Like most proprietary laser cutting software intended for a specific board it has significant disadvantages and the only open source solutions are attempts at reverse engineering.

USB Protocol

The USB plug on the board is connected directly to the CH341A communications chip and configured in parallel port (EPP19) mode. This gives it the same Vendor id and product id as other things like the M2 Nano.

The usb device is located at vendor 0x1a86 with a PID of 0x5512

Swizzling

Like many different boards there is some light swizzling for some bytes in this case the command bytes are swizzled. Half of the command byte has random data (random distribution) and the other half is control code. This gives us 4 bits of command code, 4 random bytes. The swizzling can actually thus be interpreted in several ways, but we'll put the first four bits as command and the last 4 bits as random.

The algorithm from unswizzled to swizzled form is:

   def swizzle(b, b0, b1, b2, b3, b4, b5, b6, b7):
       return ((b >> 0) & 1) << b7 | ((b >> 1) & 1) << b6 | \
              ((b >> 2) & 1) << b5 | ((b >> 3) & 1) << b4 | \
              ((b >> 4) & 1) << b3 | ((b >> 5) & 1) << b2 | \
              ((b >> 6) & 1) << b1 | ((b >> 7) & 1) << b0

   def convert(q):
       if q & 1:
           return swizzle(q, 7, 6, 2, 4, 3, 5, 1, 0)
       else:
           return swizzle(q, 5, 1, 7, 2, 4, 3, 6, 0)

Note that each lowest bit triggers a different type of swizzle. So every other bit is swizzled in a different form. The last bit remains in the same position in both so these different swizzles perfectly intermingle.

Swizzle LUT

CMD	0x00	0x01	0x02	0x03	0x04	0x05	0x06	0x07	0x08	0x09	0x0A	0x0B	0x0C	0x0D	0x0E	0x0F
0x0?	0x00	0x01	0x40	0x03	0x10	0x21	0x50	0x23	0x04	0x09	0x44	0x0b	0x14	0x29	0x54	0x2b
0x1?	0x08	0x11	0x48	0x13	0x18	0x31	0x58	0x33	0x0c	0x19	0x4c	0x1b	0x1c	0x39	0x5c	0x3b
0x2?	0x80	0x05	0xc0	0x07	0x90	0x25	0xd0	0x27	0x84	0x0d	0xc4	0x0f	0x94	0x2d	0xd4	0x2f
0x3?	0x88	0x15	0xc8	0x17	0x98	0x35	0xd8	0x37	0x8c	0x1d	0xcc	0x1f	0x9c	0x3d	0xdc	0x3f
0x4?	0x02	0x41	0x42	0x43	0x12	0x61	0x52	0x63	0x06	0x49	0x46	0x4b	0x16	0x69	0x56	0x6b
0x5?	0x0a	0x51	0x4a	0x53	0x1a	0x71	0x5a	0x73	0x0e	0x59	0x4e	0x5b	0x1e	0x79	0x5e	0x7b
0x6?	0x82	0x45	0xc2	0x47	0x92	0x65	0xd2	0x67	0x86	0x4d	0xc6	0x4f	0x96	0x6d	0xd6	0x6f
0x7?	0x8a	0x55	0xca	0x57	0x9a	0x75	0xda	0x77	0x8e	0x5d	0xce	0x5f	0x9e	0x7d	0xde	0x7f
0x8?	0x20	0x81	0x60	0x83	0x30	0xa1	0x70	0xa3	0x24	0x89	0x64	0x8b	0x34	0xa9	0x74	0xab
0x9?	0x28	0x91	0x68	0x93	0x38	0xb1	0x78	0xb3	0x2c	0x99	0x6c	0x9b	0x3c	0xb9	0x7c	0xbb
0xA?	0xa0	0x85	0xe0	0x87	0xb0	0xa5	0xf0	0xa7	0xa4	0x8d	0xe4	0x8f	0xb4	0xad	0xf4	0xaf
0xB?	0xa8	0x95	0xe8	0x97	0xb8	0xb5	0xf8	0xb7	0xac	0x9d	0xec	0x9f	0xbc	0xbd	0xfc	0xbf
0xC?	0x22	0xc1	0x62	0xc3	0x32	0xe1	0x72	0xe3	0x26	0xc9	0x66	0xcb	0x36	0xe9	0x76	0xeb
0xD?	0x2a	0xd1	0x6a	0xd3	0x3a	0xf1	0x7a	0xf3	0x2e	0xd9	0x6e	0xdb	0x3e	0xf9	0x7e	0xfb
0xE?	0xa2	0xc5	0xe2	0xc7	0xb2	0xe5	0xf2	0xe7	0xa6	0xcd	0xe6	0xcf	0xb6	0xed	0xf6	0xef
0xF?	0xaa	0xd5	0xea	0xd7	0xba	0xf5	0xfa	0xf7	0xae	0xdd	0xee	0xdf	0xbe	0xfd	0xfe	0xff

All commands will be referenced by the first 4 bits. The remaining 4 bits fit a random distribution.

Moshiboard Commands

Since command bytes have 4 bits there can only be 16 of them.

Command	Length	Code	Parameters
2nd CMD For Jump	0	0x0?	(2 bytes) (2 bytes) (2 bytes)
UNKNOWN	1	0x1?	unknown
Terminal Commands	1	0x2?	nothing. (occurs in 6 bytes increments)
Move_Y_ABS	1	0x3?	(2 byte ABS Y)
UNKNOWN	1	0x4?	unknown
Header Start	1	0x5?	(2 bytes unknown)
Move_X_ABS	1	0x6?	(2 byte ABS X)
Move_XY_ABS	1	0x7?	(2 byte ABS X) (2 byte ABS Y)
UNKNOWN	1	0x8?	unknown
UNKNOWN	1	0x9?	unknown
UNKNOWN	1	0xA?	unknown
Cut_Y_ABS	1	0xB?	(2 byte ABS Y)
UNKNOWN	1	0xC?	unknown
UNKNOWN	1	0xD?	unknown
Cut_X_ABS	1	0xE?	(2 byte ABS X)
Cut_XY_ABS	1	0xF?	(2 byte ABS X) (2 byte ABS Y)

Bitwise this implies our flags for our 4 data bytes are: Laser, X-Value, Unknown, Y-Value

Reverse engineering resources.

• The MeerK40t project has done some initial work reverse engineering the Moshiboard. https://github.com/meerk40t/moshi

Links

Official

• Moshidraw

Other Sources

• MeerK40t moshi project MeerK40t Moshi Project
• MeerK40t moshi wiki MeerK40t Moshi Wiki