The Ekdahl FAR - Command language: Difference between revisions

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If we look in the list of ''[[The Ekdahl FAR - Command langue#Variables|variables]]'' above we can see that the ''pitch bend MIDI message'' will set the ''pitch variable'' which is indeed used. Now what is the '''*4''<nowiki/>' all about? Well the ''bchsh''-command expects a ''16-bit signed'' value, meaning that a full ''harmonic shift'' downwards is equal to -32767, a full ''harmonic shift'' upwards is 32767 and no ''harmonic shift'' is 0. The ''pitch bend MIDI message'' however is only 14-bits, meaning its range is -8192 to 8192, so in order to be able to use the entire range we have to multiply ''pitch'' by 4.

This whole thing about number of bits can seem confusing but in the end it's all about how fine control you have over things; the more possible values, the more detailed control. In fact, most ''MIDI'' values are only 7-bit (!) meaning a range of 0 - 127. While this may sound like a lot of detail for something like a volume control, it is not even close to enough resolution to for instance set the ''bowing speed''. Imagine that our lowest possible note frequency is 50 Hz, that means that with a 0-127 range we can only go from 50 Hz to 127 + 50 = 177 Hz - and with no decimals! This meager range and the very coarse steps of only 1 Hz would mean the instrument would never be able to sound in tune and wouldn't even have two octaves of range.

This whole thing about number of bits can seem confusing but in the end it's all about how fine control you have over things; the more possible values, the more detailed control. In fact, most ''MIDI'' values are only 7-bit (!) meaning a range of 0 - 127. While this may sound like a lot of detail for something like a volume control, it is not even close to enough resolution to for instance set the ''bowing speed''. Imagine that our lowest possible note frequency is 50 Hz, that means that with a 0-127 range we can only go from 50 Hz to 127 + 50 = 177 Hz - and with no decimals! This meager range and the very coarse steps of only 1 Hz would mean the instrument would never be able to sound in tune and wouldn't even have two octaves of range. The idea of limiting the Ekdahl FAR to what is possible through ''MIDI'' seemed like a poor choice thus it was decided that <u>most</u> parameters will instead be 16-bit.

Now lets look at a more complex example, the <u>default</u> ''Note On MIDI message''. On a stock Ekdahl FAR, executing<pre>

rqi:mev:noteon

</pre>Will return something like<pre>

[irq]mev:noteon:'m:0,b:0,bchb:note,bmr:1,bpid:1,bpe:1,se:(velocity*512)*(1-notecount),bcsm:0'

</pre>As can be seen, there's a lot of stuff going on here! Let's break down what happens when this ''MIDI message'' is received, i.e. when a ''MIDI'' key is pressed down:

# ''m:0'' - Sets ''module'' to 0. The ''module''-command is a command that is intended for future versions of the Ekdahl FAR that may contain more than one string. For now ''0'' is the only valid value that will be accepted

# ''b:0'' - Sets ''bow'' to 0. The ''bow''-command is a command that is intended for versions of the Ekdahl FAR that may have more than one ''bow'' per string. For now ''0'' is the only valid value that will be accepted

# ''bchb:note'' - Invokes the ''bowcontrolharmonicbase-''command with the first ''parameter'' set to the ''variable note''.

# ''bmr:1'' - Sets the ''bowmotorrun''-command to '1', starting the ''bow motor''

# ''bpid:1'' - Sets the ''bowpid''-command to '1', making sure the ''PID'' is used

# ''bpe:1'' - Sets the ''bowpressureengage'' to '1' which moves the ''bowing jack'' to the ''engage position''

# ''se:(velocity*512)*(1-notecount)'' - This quite complicated equation uses the ''solenoidengage''-command, this ''command'' engages the ''hammer'' and uses the first and only ''parameter'' as the force used. Like with most ''commands'' the ''se''-command is 16-bit (0 - 65535) but the ''MIDI velocity variable'' is 7-bit (0 - 127), so to get the ''velocity'' variable to cover the entire range it needs to be multiplied with 512. The ''<nowiki/>'*(1-notecount)'''-part is a way of making sure that we are using ''legato'' mode, i.e. that the ''hammer'' is not triggered if a key is already held down when a new key is already depressed. The ''notecount''-variable

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 If we look in the list of ''[[The Ekdahl FAR - Command langue#Variables|variables]]'' above we can see that the ''pitch bend MIDI message'' will set the ''pitch variable'' which is indeed used. Now what is the '''*4''<nowiki/>' all about? Well the ''bchsh''-command expects a ''16-bit signed'' value, meaning that a full ''harmonic shift'' downwards is equal to -32767, a full ''harmonic shift'' upwards is 32767 and no ''harmonic shift'' is 0. The ''pitch bend MIDI message'' however is only 14-bits, meaning its range is -8192 to 8192, so in order to be able to use the entire range we have to multiply ''pitch'' by 4.
-This whole thing about number of bits can seem confusing but in the end it's all about how fine control you have over things; the more possible values, the more detailed control. In fact, most ''MIDI'' values are only 7-bit (!) meaning a range of 0 - 127. While this may sound like a lot of detail for something like a volume control, it is not even close to enough resolution to for instance set the ''bowing speed''. Imagine that our lowest possible note frequency is 50 Hz, that means that with a 0-127 range we can only go from 50 Hz to 127 + 50 = 177 Hz - and with no decimals! This meager range and the very coarse steps of only 1 Hz would mean the instrument would never be able to sound in tune and wouldn't even have two octaves of range.
+This whole thing about number of bits can seem confusing but in the end it's all about how fine control you have over things; the more possible values, the more detailed control. In fact, most ''MIDI'' values are only 7-bit (!) meaning a range of 0 - 127. While this may sound like a lot of detail for something like a volume control, it is not even close to enough resolution to for instance set the ''bowing speed''. Imagine that our lowest possible note frequency is 50 Hz, that means that with a 0-127 range we can only go from 50 Hz to 127 + 50 = 177 Hz - and with no decimals! This meager range and the very coarse steps of only 1 Hz would mean the instrument would never be able to sound in tune and wouldn't even have two octaves of range. The idea of limiting the Ekdahl FAR to what is possible through ''MIDI'' seemed like a poor choice thus it was decided that <u>most</u> parameters will instead be 16-bit.
+Now lets look at a more complex example, the <u>default</u> ''Note On MIDI message''. On a stock Ekdahl FAR, executing<pre>
+rqi:mev:noteon
+</pre>Will return something like<pre>
+[irq]mev:noteon:'m:0,b:0,bchb:note,bmr:1,bpid:1,bpe:1,se:(velocity*512)*(1-notecount),bcsm:0'
+</pre>As can be seen, there's a lot of stuff going on here! Let's break down what happens when this ''MIDI message'' is received, i.e. when a ''MIDI'' key is pressed down:
+# ''m:0'' - Sets ''module'' to 0. The ''module''-command is a command that is intended for future versions of the Ekdahl FAR that may contain more than one string. For now ''0'' is the only valid value that will be accepted
+# ''b:0'' - Sets ''bow'' to 0. The ''bow''-command is a command that is intended for versions of the Ekdahl FAR that may have more than one ''bow'' per string. For now ''0'' is the only valid value that will be accepted
+# ''bchb:note'' - Invokes the ''bowcontrolharmonicbase-''command with the first ''parameter'' set to the ''variable note''.
+# ''bmr:1'' - Sets the ''bowmotorrun''-command to '1', starting the ''bow motor''
+# ''bpid:1'' - Sets the ''bowpid''-command to '1', making sure the ''PID'' is used
+# ''bpe:1'' - Sets the ''bowpressureengage'' to '1' which moves the ''bowing jack'' to the ''engage position''
+# ''se:(velocity*512)*(1-notecount)'' - This quite complicated equation uses the ''solenoidengage''-command, this ''command'' engages the ''hammer'' and uses the first and only ''parameter'' as the force used. Like with most ''commands'' the ''se''-command is 16-bit (0 - 65535) but the ''MIDI velocity variable'' is 7-bit (0 - 127), so to get the ''velocity'' variable to cover the entire range it needs to be multiplied with 512. The ''<nowiki/>'*(1-notecount)'''-part is a way of making sure that we are using ''legato'' mode, i.e. that the ''hammer'' is not triggered if a key is already held down when a new key is already depressed. The ''notecount''-variable