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Added DTMF.sh to read on /dev/stdin for DTMF tones. Stops/starts radioafsk upon receiving "BAD99" tones.

DTMF.sh

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+#!/bin/sh
+
+# Shell script for reading DTMF signals on stdin. 
+# Checks for consecutive DTMF signals to create shutdown code "BAD99" 
+# Each character must come within a specific time threshold of one another. (Currently 200 ms, for 100 ms tones and 100 ms spaces)
+# This threshold can be changed by altering the TIME_THRESH variable
+
+B="DTMF: B"
+D="DTMF: D"
+NINE="DTMF: 9"
+SHUTDOWN_CODE="BAD99"
+CUR_CODE="NA"
+TIME_THRESH=210000000 #time threshold for receiving DTMF codes in nanoseconds
+LAST_CODE="NA" #previous input from stdin
+STOPPED=0
+
+while IFS='$\n' read -r line; do # read from stdin
+	DT=$(echo $line | cut -d':' -f 1) # cut first part of text
+	if [ "$DT" = "DTMF" ]; then # if input is DTMF signal
+		if [ "$line" = "$B" ]; then # No need to check time threshold if B, just start over
+			CUR_CODE="B"
+		else
+			T=$(date +"%s%N")  #get current time
+			DELTA_T="$((T-LAST_TIME))" #time change
+			THRESH="$((TIME_THRESH-DELTA_T))" 
+			if [ "$THRESH" -ge 0 ]; then # check threshold
+				case "$line" in
+					$A)
+						if [ "$CUR_CODE" = "B" ]; then
+							CUR_CODE=$CUR_CODE"A"
+						else
+							CUR_CODE="NA"
+						fi
+						;;
+					$B)
+						CUR_CODE="B"
+						;;
+					$D) 
+						if [ "$CUR_CODE" = "BA" ]; then
+							CUR_CODE=$CUR_CODE"D"
+						else
+							CUR_CODE="NA"
+						fi
+						;;
+					$NINE) 
+						if [ "$CUR_CODE" = "BAD" ] || [ "$CUR_CODE" = "BAD9" ]; then
+							CUR_CODE=$CUR_CODE"9"
+						else
+							CUR_CODE="NA"
+						fi
+						;;
+					*) 
+						CUR_CODE="NA"
+						;;
+				esac	
+			else # Time expired, reset code
+				CUR_CODE="NA"
+			fi
+		fi
+		LAST_TIME=$(date +"%s%N") # Update previous time
+		
+	fi
+	echo $CUR_CODE
+	if [ "$CUR_CODE" = "BAD99" ]; then # Check for complete code
+		CUR_CODE="NA"
+	#	echo "Termination code received" # Replace this with actual termination command
+		ID = $(pgrep radioafsk) 
+		if [ "$STOPPED" -eq 0]; then
+			kill -TSTP $ID 
+			STOPPED=1
+		else
+			kill -CONT $ID
+			STOPPED=0
+		fi 
+
+	fi
+done
+
+# while IFS='$\n' read -r line; do #read from stdin
+# 	if [ "$line" = "$SHUTDOWN_CODE" ]; then #check for code
+# 		if [ "$line" = "$LAST_CODE" ]; then #check if second in a row
+# 			T=$(date +"%s") #current time
+# 			DELTA_T="$((T - LAST_TIME))"
+# 			THRESH="$((TIME_THRESH-DELTA_T))"
+# 			if [ "$THRESH" -ge  0 ]; then
+# 			fi
+# 		fi
+# 	fi
+# 	LAST_CODE=$line #update previous input and timestamp
+# 	LAST_TIME=$(date +"%s")
+# done 
+