treadmillData

See the next phase of this project at https://github.com/eborchardt/BluetoothTreadmill

The objective of this project was to reverse engineer the serial communication from the treadmill user interface to the treadmill motor control board to see if I can extract the current speed and incline data. I have a Livestrong LS8.0T, which is manufactored by Johnson Fitness. I was initially intending to use a magnet or rotary encoder to collect the speed, but upon disassembly, I discovered a MAX3085 that appeared to connect the controls to the motor control board. After a little investigating, I found the serial communication between the controls and the motor controller to be easy to decode.

I wrote this program for an ESP32, since it has three serial ports and I had one laying around. The Serial2 Rx pin of the ESP32 is connected directly to the low side of the MAX3085 Tx IC inside the control panel and I also connected the ground pins to improve the reliability of the data.

I found what appears to be four types of commands being transmitted to the motor controller, speed, incine, stop, and one that I'm assuming is simply a keep-alive heartbeat. The basic idea seems to be that all commands begin with 0 255. Byte3 will determine the type of command, speed is 241, incline is 246. It's possible that byte4 carries some meaning as well, but I didn't investigate any further.

There is no terminating character on each command, so I needed to look for the pattern of 0 255 to detect the start of a command. Then I used byte3 to determine how many more bytes to expect and grabbed that many more bytes from the serial buffer. In the case of the speed and incline commands, they are both a total of 7 bits. Here is what I found for my treadmill:

Speed Table

byte1	byte2	byte3	byte4	byte5	byte6	byte7	Observed Speed When Sent (mph)
0	255	241	2	0	0	221	0
0	255	241	2	0	161	16	0.5
0	255	241	2	0	195	201	0.6
0	255	241	2	0	230	186	0.7
0	255	241	2	1	8	144	0.8
0	255	241	2	1	42	116	0.9
0	255	241	2	1	76	105	1
0	255	241	2	1	111	188	1.1
0	255	241	2	1	145	33	1.2
0	255	241	2	1	179	197	1.3
0	255	241	2	1	213	216	1.4
0	255	241	2	1	248	18	1.5
0	255	241	2	2	26	156	1.6
0	255	241	2	2	60	188	1.7
0	255	241	2	2	94	101	1.8
0	255	241	2	2	129	79	1.9
0	255	241	2	2	163	171	2
0	255	241	2	2	197	182	2.1
0	255	241	2	2	231	82	2.2
0	255	241	2	3	10	43	2.3
0	255	241	2	3	44	11	2.4
0	255	241	2	3	78	210	2.5
0	255	241	2	3	112	8	2.6
0	255	241	2	3	147	154	2.7
0	255	241	2	3	181	186	2.8
0	255	241	2	3	215	99	2.9
0	255	241	2	3	249	250	3
0	255	241	2	4	28	96	3.1
0	255	241	2	4	62	132	3.2
0	255	241	2	4	96	229	3.3
0	255	241	2	4	130	70	3.4
0	255	241	2	4	165	87	3.5
0	255	241	2	4	199	142	3.6
0	255	241	2	4	233	23	3.7
0	255	241	2	5	11	64	3.8
0	255	241	2	5	46	51	3.9
0	255	241	2	5	80	212	4
0	255	241	2	5	114	48	4.1
0	255	241	2	5	148	87	4.2
0	255	241	2	5	183	130	4.3
0	255	241	2	5	217	38	4.4
0	255	241	2	5	251	194	4.5
0	255	241	2	6	29	136	4.6
0	255	241	2	6	64	186	4.7
0	255	241	2	6	98	94	4.8
0	255	241	2	6	132	57	4.9
0	255	241	2	6	166	221	5
0	255	241	2	6	200	121	5.1
0	255	241	2	6	235	172	5.2
0	255	241	2	7	13	63	5.3
0	255	241	2	7	47	219	5.4
0	255	241	2	7	81	60	5.5
0	255	241	2	7	116	79	5.6
0	255	241	2	7	150	236	5.7
0	255	241	2	7	184	117	5.8
0	255	241	2	7	218	172	5.9
0	255	241	2	7	253	189	6
0	255	241	2	8	31	135	6.1
0	255	241	2	8	65	230	6.2
0	255	241	2	8	99	2	6.3
0	255	241	2	8	134	54	6.4
0	255	241	2	8	168	175	6.5
0	255	241	2	8	202	118	6.6
0	255	241	2	8	236	86	6.7
0	255	241	2	9	15	48	6.8
0	255	241	2	9	49	234	6.9
0	255	241	2	9	83	51	7
0	255	241	2	9	117	19	7.1
0	255	241	2	9	152	158	7.2
0	255	241	2	9	186	122	7.3
0	255	241	2	9	220	103	7.4
0	255	241	2	9	254	131	7.5
0	255	241	2	10	33	132	7.6
0	255	241	2	10	67	93	7.7
0	255	241	2	10	101	125	7.8
0	255	241	2	10	135	222	7.9
0	255	241	2	10	170	20	8
0	255	241	2	10	204	9	8.1
0	255	241	2	10	238	237	8.2
0	255	241	2	11	16	132	8.3
0	255	241	2	11	51	81	8.4
0	255	241	2	11	85	76	8.5
0	255	241	2	11	119	168	8.6
0	255	241	2	11	153	118	8.7
0	255	241	2	11	188	5	8.8
0	255	241	2	11	222	220	8.9
0	255	241	2	12	0	105	9
0	255	241	2	12	34	141	9.1
0	255	241	2	12	69	161	9.2
0	255	241	2	12	103	69	9.3
0	255	241	2	12	137	155	9.4
0	255	241	2	12	171	127	9.5
0	255	241	2	12	206	49	9.6
0	255	241	2	12	240	235	9.7
0	255	241	2	13	18	188	9.8
0	255	241	2	13	52	156	9.9
0	255	241	2	13	87	116	10
0	255	241	2	13	121	237	10.1
0	255	241	2	13	155	78	10.2
0	255	241	2	13	189	110	10.3
0	255	241	2	13	224	92	10.4
0	255	241	2	14	2	210	10.5
0	255	241	2	14	36	242	10.6
0	255	241	2	14	70	43	10.7
0	255	241	2	14	105	131	10.8
0	255	241	2	14	139	32	10.9
0	255	241	2	14	173	0	11
0	255	241	2	14	207	217	11.1
0	255	241	2	14	242	80	11.2
0	255	241	2	15	20	195	11.3
0	255	241	2	15	54	39	11.4
0	255	241	2	15	88	131	11.5
0	255	241	2	15	123	86	11.6
0	255	241	2	15	157	49	11.7
0	255	241	2	15	191	213	11.8
0	255	241	2	15	225	180	11.9
0	255	241	2	16	4	119	12

Incline Table

byte1	byte2	byte3	byte4	byte5	byte6	byte7	Observed Incline when Sent (%)
0	255	246	2	0	40	112	0
0	255	246	2	0	80	49	0.5
0	255	246	2	0	120	14	1
0	255	246	2	0	160	179	1.5
0	255	246	2	0	200	177	2
0	255	246	2	0	240	205	2.5
0	255	246	2	1	24	65	3
0	255	246	2	1	64	134	3.5
0	255	246	2	1	104	185	4
0	255	246	2	1	144	130	4.5
0	255	246	2	1	184	189	5
0	255	246	2	1	224	122	5.5
0	255	246	2	2	8	47	6
0	255	246	2	2	48	83	6.5
0	255	246	2	2	88	81	7
0	255	246	2	2	128	236	7.5
0	255	246	2	2	168	211	8
0	255	246	2	2	208	146	8.5
0	255	246	2	2	248	173	9
0	255	246	2	3	32	228	9.5
0	255	246	2	3	72	230	10
0	255	246	2	3	112	154	10.5
0	255	246	2	3	152	226	11
0	255	246	2	3	192	37	11.5
0	255	246	2	3	232	26	12

Stop Command

byte1	byte2	byte3	byte4	byte5	byte6
0	255	245	1	0	182

Unknown Command (Possibly a keep-alive heartbeat)

byte1	byte2	byte3	byte4	byte5
0	255	249	0	144