diff --git a/bm1397_protocol.md b/bm1397_protocol.md
index 7163fe67..48cf4f36 100644
--- a/bm1397_protocol.md
+++ b/bm1397_protocol.md
@@ -28,22 +28,26 @@ TX: 55 AA 51 09 00 08 40 A0 02 25 16 //freqbuf
 
 Sending work to the BM1397 looks like this;
 ```
-TX: 55 AA 21 96 04 04 00 00 00 00 72 E7 07 17 A9 81 51 63 EE D6 E5 43 35 3F 14 92 56 25 54 19 4E 41 31 08 E5 D7 89 4A C8 13 50 A4 48 05 B8 0E E2 E4 83 95 F8 C1 15 8D EC 07 D8 B8 AE CA DE E6 35 8C 3E E9 1C 57 5D 99 A7 52 95 DC D8 08 7B 7A D
+TX: 55 AA 21 36 38 01 00 00 00 00 20 27 07 17 8A C0 DC 63 F3 CF F8 BF FF 89 BD 99 97 74 10 44 FF 84 D0 74 30 85 44 35 E3 DE 76 0B CC 28 54 A2 FA 12 42 98 00 00 00 00 00 00 00 00 92 C7 00 00 FB 7A BB 8C 33 75 29 7C D8 F6 7E 14 1B D3 0F 2F D1 A0 82 66 00 00 00 20 7F D3
 ```
 
 How does this big work field break down?
 
-- `55 AA` -> (most) All of the commands to the BM1397 start with this
-- `21` -> always 21. like bitcoin, always 21 million coins?
-- `96` -> length
-- `04` -> jobID
-- `04` -> midstates
-- `00 00 00 00` -> always zero. Is this the starting nonce?
-- `72 E7 07 17` -> nbits
-- `A9 81 51 63` -> ntime. if you flip the endianess, this is unixtimestamp for Thu Oct 20 2022 17:13:13 GMT. boom!
-- `EE D6 E5 43` -> last 4 bytes of the merkle root
-- `35 3F 14 92 56 25 54 19 4E 41 31 08 E5 D7 89 4A C8 13 50 A4 48 05 B8 0E E2 E4 83 95 F8 C1 15 8D` -> midstate computed from the first 64 bytes of the header
-- `EC 07 D8 B8 AE CA DE E6 35 8C 3E E9 1C 57 5D 99 A7 52 95 DC D8 08 7B 7A D` -> ?? another midstate?
+`55 AA` - (most) All of the commands to the BM1397 start with this
+`21` - always 21. like bitcoin, always 21 million coins?
+`36` - Length
+`38` - JobID
+`01` - Midstates
+`00 00 00 00` - always zero. Is this the starting nonce?
+`20 27 07 17` - nbits
+`8A C0 DC 63` - ntime → Fri Feb 03 2023 08:06:34 GMT
+`F3 CF F8 BF` - last 4 bytes of the merkle root
+`FF 89 BD 99 97 74 10 44 FF 84 D0 74 30 85 44 35 E3 DE 76 0B CC 28 54 A2 FA 12 42 98 00 00 00 00` - midstate computed from the first 64 bytes of the header
+`00 00 00 00 92 C7 00 00 FB 7A BB 8C 33 75 29 7C D8 F6 7E 14 1B D3 0F 2F D1 A0 82 66 00 00 00 20` - uhoh, what's this?
+`7F D3` - checksum
+
+- for the checksum use crc16_false() on all bytes except for `55 AA`
+
 
 when the BM1397 finds a nonce that makes a hash below the difficulty (which difficulty is that?) it responds with;
 ```
diff --git a/crc.py b/crc.py
new file mode 100644
index 00000000..ed09eeb9
--- /dev/null
+++ b/crc.py
@@ -0,0 +1,72 @@
+crc16_table = [
+	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
+	0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
+	0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
+	0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
+	0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
+	0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
+	0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
+	0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
+	0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
+	0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
+	0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
+	0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
+	0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
+	0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
+	0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
+	0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
+	0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
+	0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
+	0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
+	0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
+	0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
+	0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
+	0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
+	0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
+	0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
+	0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
+	0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
+	0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
+	0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
+	0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
+	0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
+	0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
+]
+
+# CRC-16/CCITT
+def crc16(buffer):
+
+	crc = 0;
+	for x in buffer:
+		crc = crc16_table[((crc >> 8) ^ x) & 0xFF] ^ (crc << 8);
+
+	return crc;
+
+
+# CRC-16/CCITT-FALSE
+def crc16_false(buffer):
+
+	crc = 0xffff;
+	for x in buffer:
+		crc = crc16_table[((crc >> 8) ^ x) & 0xFF] ^ (crc << 8);
+
+	return [((crc >> 8) & 0xFF), (crc & 0xFF)];
+
+
+# calculates the BM1387 CRC for ptr array
+def crc8(ptr):
+	c = [1, 1, 1, 1, 1]
+	ptr_idx = 0
+
+	for i in range(8 * len(ptr)):
+		c1 = c[1]
+		c[1] = c[0]
+		c[0] = c[4] ^ (1 if (ptr[ptr_idx] & (0x80 >> (i % 8))) else 0);
+		c[4] = c[3]
+		c[3] = c[2]
+		c[2] = c1 ^ c[0]
+
+		if (((i + 1) % 8) == 0):
+			ptr_idx+=1
+
+	return (c[4] * 0x10) | (c[3] * 0x08) | (c[2] * 0x04) | (c[1] * 0x02) | (c[0] * 0x01)