Firmware-75 Command-094

MIDI STATUS (94, 5Eh)

This command enables / disables MIDI running status and active sensing, and the sending of a MIDI byte each time the USB-microDig's sampling loop starts.

When running status is enabled the USB-microDig will always send the MIDI status byte each time it sends a MIDI message. For example, if the running status feature of the USB-microDig is ON then the output MIDI message from the USB-microDig for two MIDI Note-On message (9xh where x is a number from 0 to 15 representing the MIDI channel number between 1 and 16) on MIDI channel 1 will be “90h n1 v1 90h n2 v2”. Where 90h is the running status byte for a Note-On message on channel 1, n1 & n2 are the note number values between 0 to 127 (for MIDI Note-On 1 and 2) and v1 & v2 are the velocity values between 0 and 127 for MIDI Note-On 1 and 2. When the MIDI running status feature is disabled the USB-microDig will only send a running status byte when it is different from the last one that was sent. For example the running status for two Note-On messages would be: “90h n1 v1 n2 v2”. This feature is useful when the data stream is large. It removes unwanted repetition of the current status so that this can slightly reduce the latency and the amount of MIDI data flow.

When active sensing is enabled the USB-microDig will send a single MIDI System Exclusive Realtime byte 254 (FEh) every 300 ms. Connected MIDI devices can use this information to turn off MIDI notes if the active sensing message is not received, and hence avoid "hanging notes".

When sampling interval marking is enabled the USB-microDig will send a single MIDI System Exclusive Realtime byte 253 (FDh) each time the sampling loop is started. By measuring the time passed between the receipt of these bytes it's possible to more accurately determine the actual sampling interval of the USB-microDig. This may be useful when the sampling interval is below 10 ms and many sensors are connected and/or many processing features are enabled.

Upon completion of the MIDI STATUS command the same message is sent out by the USB-microDig.

The [BODY] of the MIDI STATUS command is:

00000zyx:	x = 0; MIDI running status disabled
	x = 1; MIDI running status enabled
	y = 0; MIDI active sensing disabled
	y = 1; MIDI active sensing enabled
	z = 0; Sampling interval marking disabled
	z = 1; Sampling interval marking enabled