L3G4200D raw data

[ger]

Hi,

 

I'm having a bit of trouble understanding the output of the L3G4200D Gyroscope.

 

When I run the sample program I get an output on all axis between 0 and 255. It doesn't seem to distinguish between clockwise rotation and anti-clockwise rotation.

 

Here's an example of the output from running https://github.com/jrowberg/i2cdevlib/blob/master/Arduino/L3G4200D/Examples/L3G4200D_raw/L3G4200D_raw.ino (excluding Serial.print("angular velocity:\t"); )

 

Does anyone know if this is correct?

Initializing I2C devices...
Testing device connections...
L3G4200D connection successful
	183	213	32
	8	253	19
	9	255	23
	11	0	26
	8	252	17
	11	255	24
	11	253	16
	7	252	20
	8	253	17
	12	254	17
	8	1	18
	10	255	17
	12	250	19
	5	251	19
	13	0	22
	10	254	19
	13	254	18
	10	254	18
	13	254	15
	13	1	25
	10	254	20
	14	255	17
	13	250	20
	18	255	21
	11	0	19
	14	1	14
	14	255	16
	12	0	17
	7	255	19
	10	252	19
	13	254	18
	10	248	14
	7	254	15
	10	252	20
	8	253	19
	10	251	14
	11	254	18
	11	3	19
	10	255	12
	9	252	18
	13	3	20
	9	255	18
	9	4	24
	13	1	18
	8	4	17
	16	0	16
	10	0	22
	7	1	12
	15	255	16
	10	1	21
	11	255	23
	6	0	19
	9	252	23
	11	4	15
	7	252	20
	8	1	20
	5	1	20
	11	254	15
	7	252	16
	15	255	15
	11	254	18
	14	250	20
	14	254	20
	6	255	25
	8	250	21
	7	255	22
	12	253	23
	11	0	14
	11	252	20
	8	253	24
	10	251	16
	5	251	18
	12	254	20
	18	254	18
	15	254	24
	3	255	22
	5	251	15
	9	0	18
	7	249	20
	12	255	22
	7	252	21
	12	3	19
	11	253	22
	13	253	17
	13	1	15
	13	1	21
	8	251	16
	7	255	16
	13	250	23
	8	255	16
	10	252	18
	9	1	20
	10	255	17
	14	252	18
	9	251	13
	11	254	19
	12	253	22
	9	1	15
	13	251	19
	9	255	20
	6	249	16
	8	253	17
	10	1	24
	8	253	18
	9	253	16
	10	248	22
	7	251	21
	8	3	21
	10	253	19
	10	0	23
	10	250	19
	5	255	19
	11	250	20
	11	252	26
	10	250	19
	11	251	12
	10	254	15
	12	0	18
	10	255	23
	7	0	21
	9	250	22
	13	251	16
	8	248	22
	9	0	18
	9	255	24
	15	254	17
	7	255	25
	10	255	19
	14	253	19
	13	252	25
	11	2	17
	9	255	18
	12	5	21
	13	254	20
	13	254	17
	13	0	20
	12	0	20
	11	250	25
	6	255	16
	16	1	17
	14	253	19
	10	255	19
	11	255	19
	9	254	24
	10	1	17
	12	250	18
	7	5	13
	9	255	21
	4	249	20
	15	255	15
	9	245	16
	7	248	18
	9	1	17
	9	252	21
	7	0	16
	14	252	17
	9	255	18
	10	1	20
	12	251	17
	14	253	19
	10	1	17
	12	255	13
	10	252	14
	10	254	16
	11	255	17
	7	255	21
	10	0	21
	10	254	21
	9	0	20
	9	254	16
	10	0	15
	12	254	13
	8	250	16
	14	0	11
	12	255	16
	12	3	19
	7	251	25
	11	255	18
	10	255	22
	9	255	15
	11	254	19
	12	251	17
	13	255	18
	8	253	19
	14	0	17
	9	254	19
	16	250	19
	7	1	20
	11	1	17
	8	255	20
	7	1	16
	11	0	15
	17	1	19
	11	0	22
	12	254	20
	13	253	17
	12	255	17
	12	254	28
	11	252	21
	13	252	20
	14	254	18
	12	251	18
	11	251	22
	10	253	18
	9	0	23
	15	248	20
	13	0	15
	10	254	20
	10	255	19
	10	254	18
	7	249	21
	10	251	21
	7	1	23
	7	252	15
	6	253	19
	9	254	18
	13	253	18
	8	246	21
	11	255	14
	12	0	13
	7	254	22
	12	252	20
	7	254	20
	13	251	18
	12	254	13
	9	249	17
	8	253	20
	13	255	20
	11	253	17
	14	254	21
	16	2	19
	12	255	15
	10	255	17
	11	0	20
	9	253	17
	12	0	21
	11	247	16
	11	0	22
	8	0	15
	8	254	17
	13	253	20
	9	1	14
	13	253	17
	8	252	19
	13	255	18
	11	252	23
	9	252	18
	14	253	16
	9	4	24
	18	253	25
	9	251	18
	6	0	18
	12	1	21
	18	254	17
	10	2	19
	14	254	17
	10	255	24
	9	251	18
	10	0	16
	11	3	18
	7	254	24
	8	1	16
	7	255	18
	10	1	16
	9	254	20
	15	249	20
	6	0	14
	13	252	23
	10	253	18
	7	254	20
	10	254	19
	10	1	19
	11	255	20
	13	250	17
	17	253	15
	13	251	18
	6	255	19
	7	249	15
	11	253	16
	12	252	16
	9	254	18
	10	2	19
	7	3	23
	10	252	19
	8	2	12
	6	255	17
	14	254	15
	11	251	16
	14	2	14
	7	1	22
	9	253	17
	14	0	17
	15	252	16
	11	250	21
	5	255	16
	8	253	18
	8	253	25
	11	253	18
	10	253	13
	9	252	15
	7	0	20
	11	255	19
	11	253	21
	5	255	16
	13	251	15
	13	254	19
	10	5	9
	9	1	17
	4	254	15
	12	254	11
	9	1	17
	10	254	19
	11	254	22
	13	254	16
	12	5	20
	11	1	20
	13	252	21
	13	252	18
	8	254	22
	16	253	20
	10	253	22
	8	252	17
	9	253	15
	14	255	17
	11	0	14
	8	252	14
	11	0	17
	8	249	20
	8	247	17
	12	1	20
	9	255	21
	11	0	26
	10	255	22
	10	3	15
	9	0	18
	8	253	17
	10	252	14
	6	255	15
	11	248	21
	10	255	25
	5	254	20
	8	254	17
	13	252	21
	13	254	17
	9	254	17
	7	1	23
	4	253	20
	13	254	20
	9	254	18
	5	251	21
	10	2	17
	9	2	21
	16	252	16
	15	253	16
	6	255	15
	12	254	20
	11	0	19
	10	254	17
	13	1	19
	11	255	17
	11	251	21
	10	0	19
	9	2	21
	10	0	21
	14	249	18
	14	250	16
	14	250	18
	12	1	14
	13	254	16
	9	254	16
	10	252	19
	9	250	13
	6	255	17
	7	251	16
	16	2	23
	13	253	20
	8	2	20
	9	3	22
	12	0	27
	16	255	94
	11	1	120
	13	3	104
	238	88	101
	0	226	240
	52	142	52
	242	158	234
	66	128	179
	137	235	17
	234	154	7
	117	1	152
	25	76	231
	189	157	44
	1	121	104
	122	198	127
	102	126	232
	216	201	119
	95	174	108
	255	122	49
	115	129	78
	108	56	218
	140	135	143
	121	206	161
	61	187	0
	13	216	107
	80	45	51
	165	187	158
	69	135	29
	44	97	142
	9	171	119
	6	49	157
	81	109	232
	41	185	148
	5	232	242
	146	242	217
	20	252	146
	103	211	101
	27	135	253
	235	202	30
	173	252	118
	41	127	59
	203	43	63
	102	45	105
	189	218	142
	121	158	213
	15	190	44
	39	82	34
	173	69	128
	239	221	38
	13	123	193
	110	170	216
	114	32	34
	144	115	36
	17	76	104
	251	224	5
	1	240	197
	74	61	36
	166	236	64
	3	59	236
	163	120	138
	123	107	236
	192	27	0
	147	51	196
	118	125	191
	9	227	224
	220	170	24
	61	189	61
	13	249	96
	143	116	131
	21	32	56
	15	3	44
	18	10	40
	25	3	52
	23	251	148
	18	249	88
	18	250	64
	136	168	78
	9	250	170
	19	238	162
	12	247	52
	6	220	15
	10	15	19
	12	17	16
	7	1	20
	8	247	20
	8	248	23
	15	253	16
	12	12	18
	10	255	17
	9	254	18
	13	2	19
	14	249	17
	9	0	18
	11	252	16
	10	4	18
	13	251	14
	11	0	18
	6	0	20
	12	0	24
	8	255	17
	14	252	22
	12	252	20
	11	0	21
	8	255	19
	11	252	19
	8	0	14
	6	0	19
	5	6	19
	11	254	16
	4	250	207
	13	0	25
	9	250	26
	13	252	25
	9	254	20
	17	7	40
	10	0	246
	15	2	245
	12	248	18
	5	249	25
	10	0	20
	11	3	35
	10	6	251
	8	255	62
	11	0	75
	10	245	95
	9	238	47
	11	249	18
	14	245	23
	40	225	47
	128	229	66
	224	64	96
	196	252	72
	41	230	164
	162	125	48
	227	241	27
	226	245	249
	237	230	232
	120	96	120
	162	100	67
	7	9	241
	112	172	13
	30	224	140
	102	162	244
	63	53	56
	89	228	166
	248	173	152
	14	94	190
	153	6	96
	137	227	199
	124	199	77
	56	146	228
	68	250	158
	3	5	135
	165	210	67
	13	13	78
	32	17	225
	150	208	168
	129	112	69
	184	240	152
	236	231	29
	42	129	193
	207	8	32
	70	206	85
	57	223	14
	111	228	242
	176	6	141
	121	130	167
	55	103	163
	245	62	71
	133	246	243
	69	210	46
	51	182	4
	118	126	223
	14	60	213
	223	71	224
	237	16	252
	10	13	11
	29	66	20 

[deamonata]

it sounds like you are using a unsigned short type variable, It would be strange for you to be getting such a perfect range otherwise. I would assume that you would be better of using a signed int data type that would give you a range of -32768

 to 32767.

[ger]

it sounds like you are using a unsigned short type variable, It would be strange for you to be getting such a perfect range otherwise. I would assume that you would be better of using a signed int data type that would give you a range of -32768

 to 32767.

 

Hi Deamonata,

 

Thanks for the reply, I've tried changing the variable type to a number of different ones and nothing seems to change. From http://www.nongnu.org/avr-libc/user-manual/group__avr__stdint.html it looks like int16_t (what's currently being used) is a signed integer.

 

Since posting this I've tried using the L3G library (https://github.com/pololu/L3G/tree/master/L3G) and that seems to be giving a more reasonable range. (I thought it was -65,535 to 65536, which is a bit strange so I'll check when I get home, I'm probably mistaken).

[deamonata]

-65,535 to 65536 would be the range of a 32 bit int (long). hmm bit strange that it is capping out at 255 do you have a logic analyser, it would be useful to sniff the data line and see what the data is that you are getting from the L3G4200D