From a25b1d3919cbaf5ac569df06a5c35e32c0445af3 Mon Sep 17 00:00:00 2001
From: Dobrica Pavlinusic <dpavlin@rot13.org>
Date: Tue, 7 Jan 2020 16:25:34 +0100
Subject: [PATCH] MH-Z19B Co2 sensor

---
 mh-z19b.pl | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100755 mh-z19b.pl

diff --git a/mh-z19b.pl b/mh-z19b.pl
new file mode 100755
index 0000000..b71b365
--- /dev/null
+++ b/mh-z19b.pl
@@ -0,0 +1,55 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+# sudo apt install libdevice-serialport-perl libdata-dump-perl
+use Device::SerialPort;
+use Time::HiRes;
+use Data::Dump qw(dump);
+
+my $port = shift @ARGV || '/dev/ttyUSB0';
+my $influx_url = shift @ARGV || 'http://10.13.37.229:8186/write?db=telegraf';
+$influx_url = 'http://10.13.37.92:8086/write?db=rot13';
+
+my $s = new Device::SerialPort( $port ) || die $!;
+$s->baudrate(9600);
+$s->databits(8);
+$s->parity('none');
+$s->stopbits(1);
+$s->handshake('none');
+$s->read_char_time(0);
+$s->read_const_time(10);
+$s->debug(1);
+
+$s->write("\xFF\x01\x86\x00\x00\x00\x00\x00\x79");
+
+while (1) {
+
+	my ($len, $string) = $s->read(9);
+	my $t = int( Time::HiRes::time() * 1_000_000_000 );
+	die $! if ! defined($len);
+	if ( $len > 0 ) {
+		my @v = unpack('C*', $string);
+		#warn "# $len ",dump($string), dump( @v ), $/;
+
+		my $sum = 0;
+		foreach my $i ( 1 .. $#v - 1 ) {
+			$sum += $v[$i];
+			$sum = $sum & 0xff;
+		}
+		$sum = 0xff - $sum + 1;
+
+		my $checksum = $v[8] || die "no checksum";
+		my $co2 = $v[2] * 255 + $v[3];
+		if ( $v[0] == 0xff && $sum == $checksum ) {
+			my $influx = "mh-z19b,dc=trnjanska co2=$co2 $t";
+			print "$influx\n";
+			system "curl --silent -XPOST '$influx_url' --data-binary '$influx'"
+		}
+		sleep 1;
+		$s->write("\xFF\x01\x86\x00\x00\x00\x00\x00\x79");
+	}
+
+};
+
+
+$s->close;
-- 
2.20.1