First cut

diff --git a/CurrentCost.pl b/CurrentCost.pl
new file mode 100755 (executable)
index 0000000..327b60b
--- /dev/null
+++ b/CurrentCost.pl
@@ -0,0 +1,77 @@
+#!/usr/bin/perl -w
+
+# Reads data from a Current Cost device via serial port.
+# Run me from /etc/crontab with a line like:
+#     @reboot root /usr/local/rrd/CurrentCost.pl
+
+use strict;
+use Device::SerialPort qw( :PARAM :STAT 0.07 );
+
+my $PORT = "/dev/ttyUSB0";
+# TODO: If multiple ttyUSBs around, autodetect which is which...
+
+my $BAUD = "57600";
+my $RRD = "/var/lib/collectd/rrd/currentcost.rrd";
+
+my $a = shift @ARGV;
+if (defined $a && $a eq "--create-rrd") {
+my $cmd = <<EOT;
+mkdir -p `dirname $RRD`
+rrdtool create "$RRD" --step 6 \\
+DS:Power:GAUGE:180:0:U \\
+DS:Temperature:GAUGE:180:U:U \\
+RRA:AVERAGE:0.5:1:3200 \\
+RRA:AVERAGE:0.5:6:3200 \\
+RRA:AVERAGE:0.5:36:3200 \\
+RRA:AVERAGE:0.5:144:3200 \\
+RRA:AVERAGE:0.5:1008:3200 \\
+RRA:AVERAGE:0.5:4320:3200 \\
+RRA:AVERAGE:0.5:52560:3200 \\
+RRA:AVERAGE:0.5:525600:3200 \\
+RRA:MIN:0.5:1:3200 \\
+RRA:MIN:0.5:6:3200 \\
+RRA:MIN:0.5:36:3200 \\
+RRA:MIN:0.5:144:3200 \\
+RRA:MIN:0.5:1008:3200 \\
+RRA:MIN:0.5:4320:3200 \\
+RRA:MIN:0.5:52560:3200 \\
+RRA:MIN:0.5:525600:3200 \\
+RRA:MAX:0.5:1:3200 \\
+RRA:MAX:0.5:6:3200 \\
+RRA:MAX:0.5:36:3200 \\
+RRA:MAX:0.5:144:3200 \\
+RRA:MAX:0.5:1008:3200 \\
+RRA:MAX:0.5:4320:3200 \\
+RRA:MAX:0.5:52560:3200 \\
+RRA:MAX:0.5:525600:3200
+EOT
+       system($cmd);
+       exit 0;
+}
+
+die "unknown argument" if (defined $a);
+
+die "No RRD ($RRD)" unless -f $RRD;
+
+my $ob = Device::SerialPort->new($PORT);
+unless (-c $PORT && defined($ob)) {
+       die "no serial port!";
+}
+
+$ob->baudrate($BAUD);
+$ob->write_settings;
+
+unless (open(SERIAL, "+>$PORT")) {
+       die "opening serial port: $!";
+};
+
+while (my $line = <SERIAL>) {
+    if ($line =~ m!<tmpr> *([\-\d.]+)</tmpr>.*<ch1><watts>0*(\d+)</watts></ch1>!) {
+        my $watts = $2;
+        my $temp = $1;
+               $watts="U" unless defined $watts;
+               $temp="U" unless defined $temp;
+               my $rv = system("rrdupdate", "$RRD", "N:$watts:$temp");
+               die "rrdupdate failed (system $rv, process return ".($rv>>8).")" unless $rv==0;
+    }
+}