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Using NACK & ACK
Testing the sensor for an ACK should be done prior to sending any commands or queries. It is
only necessary to send the address byte with the associated sensor number. A write with no data
should be used, if a read is utilized and the sensor ACK's indicating that it is ready, it will expect
further data causing an error when it is not sent.
●The list below details how to use ACK & NACK for testing. At the end of this section is a
complete measurement example. ACK.NACK should be utilized prior to beginning any
commands or queries to assure readiness. For example after sending a measurement command use
ACK/NACK prior to any further communication.
1. Write sensor address only (one byte). Bit 0 = 0 (write) - do not use read (bit 0=1)
2. Test for ACK if NACK
a. If NACK Wait 1ms minimum or expected cmd execution time – then retry
i. Optional time out testing
b. If ACK proceed
DOC: SPII2CHDWBrief - V2.71 07/25/2017
Figure 11 - ACK & NACK Tests
PAGE 15
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