SerialReadTest.csd

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-n  ;;;no output
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o serialRead.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr  = 44100
ksmps = 500 ; the default krate can be too fast for the arduino to handle
nchnls = 2
0dbfs  = 1

instr 1

iPort serialBegin "COM6", 9600			;connect to the arduino with baudrate = 9600

kGain init 16							;read our knob value
kVal serialRead iPort
if (kVal != -1) then
    kGain = kVal/128
endif

aSig in								;get our audio input and get its rms
kRms rms aSig*kGain

kRms = kRms*kRms*255						;scale the rms to a good value for the LED and send it out
serialWrite iPort, (kRms < 255 ? kRms : 255)			;must be in range: 0-255

endin
</CsInstruments>
<CsScore>
f 1 0 1024 10 1 1 1 1 1 1

i 1 0 200
e
</CsScore>
</CsoundSynthesizer>