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sensor. Warning: The Sensor uses interrupts to process SPI communications; requests should be
limited to less than one per millisecond. This will allow the sensor sufficient time to respond as
well as process the commands.
Sensor Status Byte (STB)
Once Busy/Ready indicates the sensor is ready to process a command, the status byte can be
utilized to determine if a measurement is complete. Status byte meaning is detailed in the
sensor's programming guide. Bit 4 (Value 16) indicates that data is available. An alternate
method is to use the three return length bytes, if these are zero, no data is ready. This indicates
that the sensor has not completed the measurement (if one is in process).
Bit
Value Meaning
0
1
Not in use
1
2
Device Status Condition-Future implementation
2
4
One or more errors are present in the error queue
3
8
Questionable Status Summary– Future implementation
4
16
The output buffer contains a message
5
32
Event Status Bit– Future implementation
6
64
Master Summary Status-Future implementation
7
128
Status Summary-Future implementation
Measurement Processing Time
To assure the fastest measurement, the user should determine the time required to make the
measurement in advance, and then limit requests to the sensor until such time has elapsed
(during the measurement). The use of READ? or FETCh? are recommended. MEAS? will cause the
sensor to adjust the number of averages and will result in a varying measurement time that could
be very long if the measured power level is low.
Header Details
Command Headers are used to manage SPI communications. The headers include data length,
Busyness information and status so that the user can properly communicate with the sensor.
The maximum allowable SPI baud rates allow communication at rates that are greater than
power measurements can be made. As a result of this and other factors, checking the sensor for
busyness is an important part of SPI communication.
Additional communication information is provided in example code and demonstration kits.
DOC: SPII2CHDWBrief - V2.71 07/25/2017
Figure 23 - Sensor Status Byte
PAGE 25
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