attenuation_measurement

#! /bin/bash

#find the photodiode directory with help_num as an input argument
help_num=$1
SYSFS_ADC_DIR="/sys/devices/ocp.3/helper."$help_num"/AIN0"

#find and touch the file_name that it will output to it
file1=$2
touch $file1

#set up averaging variables
toAverage=25
average=0
rms=0
count=0

#set trigger level to loop over
Trigger3="/sys/class/gpio/gpio46"
trig3=`cat "$Trigger3/value"`
buf1=2
buf2=3
buf3=4
#always loops while trigger3 is activated
while (( $trig3 == 1 )); do
	
	  #gets the value of trigger3 from the directory
	  buf1=`cat "$Trigger3/value"`
	  if [ $buf1 == $buf2 ] && [ $buf2 == $buf3 ]; then
		trig3=$buf1
	  else
		buf3=$buf2
		buf2=$buf1
	  fi
	  total=0
	  
	  #finds the voltage from the photodiode and reads 25 times
	  for i in {0..24}; do
	  	  adc=`cat "$SYSFS_ADC_DIR"`
		  volts[$i]=$adc
		  total=$(( $total + $adc ))
		  sleep 0.02
	  done
	  
	  #finds the average from the total voltage read over 25 times
	  averages=`./divide $total $toAverage`

	  #finds the error on the mean for the voltage
	  rmsSum=0
	  k=0
	  for k in {0..24}; do
		  foilvar=`./foil ${volts[$k]} $averages`
		  rmsSum=`./add $rmsSum $foilvar`
	  done
	  rms=`./find_error $rmsSum $toAverage`
	  
	  #temperature=`./temp_read`	  
	  #reads the values out to the file_name
	  echo `date +%s.%3N`" "$averages" "$rms>> $file1
	  echo `date +%s.%3N`" "$averages" "$rms

	  #increments the time count
	  count=`./add $count 0.5`
done