Analog Devices ADXL180 iMEMS Manual page 33

Table 32. Phase 2 Mode 2 User Bit Mapping
User Bit Device Data Bit Name
U11 SYEN
U10 RG2
U09 RG1
U08 RG0
U07 UD7
U06 UD6
U05 UD5
U04 UD4
U03 UD3
U02 UD2
U01 UD1
U00 UD0
Mode 3
Device Data
In Phase 2 Mode 3, the 10-bit data codes, −512 (0x200) to −481
(0x21F), are used to transmit the device data. The data coding
is shown in Table 34 and in Figure 25. One 4-bit nybble of the
device data (encoded as one of 16 nybble codes) is transmitted
in each 10-bit message. The number of the data nybble is identi-
fied by the preceding nybble number (NN) code as detailed in
Table 33. This allows a total of (16 × 4) = 64 unique bits of device
data to be transmitted during Phase 2. Each message is repeated
PHASE 1
NN1 DATA1
Table 33. Phase 2 Mode 3 Device Data Mapping
Device Data Nybble No.
1
1
2
3
4
5
6
7
8
9
10
NN1 DATA1 NN2 DATA2
32 MESSAGES 32 MESSAGES
Figure 25. Mode 3 Device Data Transmission
Protocol ID
Number of nybbles sent
Manufacturer
Sensor type
2
Sensor range
BDE and RS
User data (UD Bits[7:4])
User data (UD Bits[3:0])
Serial number (Bits[31:28])
Serial number (Bits[27:24])
32 times for each nybble number. The specific meaning of each
data nybble is defined in Table 33. The total number of messages
transmitted during Phase 2 in Mode 3 is (32 × 16) = 512.
User Register (UREG)
The User Register UREG[7:0], in Mode 3 transmit during
Nybble 7 (UREG[7:4]) and Nybble 8 (UREG[3:0]).
Use with State Vector Enabled
When Mode 3 is selected with the state vector enabled and the
auto-zero not enabled, the full range sensor data coding is used
(see the Data Frame Transmission Format section). Therefore,
the positive and negative full-scale ends of the sensor data range
overlap with the device data and status data codes. The state vector
distinguishes between the types of transmitted data. The state
vector identifies the device data (state vector = 001b) and status
codes as status/error data (state vector = 110b). Normal opera-
tion sensor data has a state vector of 000b (see Table 19).
Illegal Configuration: Mode 3 and 8-Bit Data
A configuration error is flagged if Phase 2 Mode 3 is selected
and the configuration register is programmed to select the 8-bit
data mode. In this case, the error state is entered immediately
instead of Phase 1. See the Error Detection section for more
information.
PHASE 2
NN2 DATA2 NN16
Definition
16
Analog Devices
Accelerometer
100 g
50 g
200 g
Other
RS = 0, BDE = 0
RS = 0, BDE = 1
RS = 1, BDE = 0
RS = 1, BDE = 1
0 to 255
0 to 255
Rev. 0 | Page 33 of 56
PHASE 3
DATA DATA
NN16
16 16
32 MESSAGES
Binary Code Nybble Sent
001 0011
10000 0000
101 1010
00001 0001
0000 0000
0001 0001
0010 0010
0011 0011
0000 0000
0001 0001
0010 0010
0011 0011
3
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ADXL180