PNI SENtral - Manual (Page 47)

PNI Sensor Corporation Doc #1018049 R03
SENtral Technical Data Sheet Page 46
Now the host can read the RetrieveParamByte registers to obtain the parameter value. Note
the host can read the ParamAcknowledge and RetrieveParamByte registers using a single
five-byte read transaction. Also, the RetrieveParamByte values are given in little Endian
format, such that RetrieveParamByte3 contains the least significant byte of the parameter’s
4-byte float value. The host can continue reading other parameters by varying (normally
incrementing) the parameter number contained in the ParamRequest registers. Reading the
ParamAcknowledge register is optional for subsequent parameters. The procedure is
terminated by the host writing 0x00 to the ParamRequest and AlgorithmControl registers.
Interleaving Parameter Load and Retrieve
The host can interleave the Parameter Load and Parameter Retrieve processes during a single
process invocation. This can be done for each parameter by setting the MSB bit of the
ParamRequest register appropriately. Note that SENtral can be copying a new value into a
RetrieveParamByte register while a Parameter Load operation is requested. Interleaving can
be utilized by the host as an additional check that the parameter value was updated correctly.
Parameters
The parameter numbers and associated names are given below in Table A3-2. A discussion
on the WarmStart, SensorRange, and DriverID parameters follows.
Table A3-2: Parameter Numbers
Parameter
Number
Parameter Name
ParamRequest
Value
Load Retrieve
1 – 35
WarmStart[1] to
WarmStart[35]
0x81 to
0xA3
0x01 to
0x23
36 – 73 Reserved
74 SensorRange[mag:accel] 0xCA 0x4A
75 SensorRange[gyro] 0xCB 0x4B
77 DriverID[mag:accel] -- 0x4D
78 DriverID[gyro] 0x4E
80 AlgorithmID -- 0x50
WarmStart
A significant number of parameters are used in the SENtral algorithm as it executes,
and these parameters are refined as the SENtral device is used. These include