Command Code:

cmdMPD_SET = 46

The Packet:

0		1		2		3		4
address		3		cmdMPD_SET		CtrID		NPULSES

CtrID -	Index of the counter.  Range is 0-7.
NPULSES -	1-byte pulse count failure limit (1-127)

Description:

This command initializes a missing-pulse detector for use by reflexes.  A counter ID that is out of range will generate an error message.  A pulse count failure limit that is out of range will generate an error message.  There is no reply packet.

A missing-pulse detector is a special type of counter.  The 8 counter resources available to the BrainStem may be used as normal counters or missing-pulse detectors.

A normal counter generates a raw input when the count reaches zero after a decrement or increment operation.  A missing-pulse detector generates a raw input after several consecutive cmdMPD_CHK commands fail to detect a valid pulse.  This number of failures is the pulse count failure limit mentioned above.  The cmdMPD_CHK command automatically resets the failure limit to the initial value after detecting a valid pulse.

A typical application for this function is to detect cycles in a varying digital or analog signal.  A reflex loop must sample the signal at a constant rate and apply the cmdMPD_CHK function to check for pulses.  Valid pulses, characterized by 0-1 transitions, continually reset the missing-pulse detector.  A lack of pulses will cause a raw input.  Then another reflex may act in response to the lack of pulses.