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 $port = shift @ARGV || '/dev/serial/by-path/platform-3f980000.usb-usb-0:1.5:1.0';
+my $influx_url = shift @ARGV || 'http://10.13.37.92:8086/write?consistency=any&db=rot13';
my $s = new Device::SerialPort( $port ) || die $!;
$s->baudrate(9600);
while (1) {
+ alarm 3;
+ # Usb serial which I'm using is buggy and blocks from time to time.
+ # This will ensure that we have passed here every 3 seconds
+ # or we will be killed and systemd will restart us
+
my ($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 ), $/;
+ #warn "# $len ",dump($string), dump( @v ), $/;
+
+ my $sum = 0;
+ # -2 is specified in datasheet, next byte is 0 so it's same as -1
+ foreach my $i ( 0 .. $#v - 2 ) {
+ $sum += $v[$i];
+ $sum = $sum & 0xff;
+ }
+ $sum = ~$sum & 0xff;
+
+ my $checksum = $v[8];
my $pcnt = $v[3] + ( $v[4] / 100 );
- if ( $v[0] == 0xff ) {
- my $influx = "zph02,dc=trnjanska pm25_pcnt=$pcnt";
+ if ( $v[0] == 0xff && $sum == $checksum ) {
+ my $influx = "zph02,dc=trnjanska pm25_pcnt=$pcnt $t";
print "$influx\n";
system "curl --silent -XPOST '$influx_url' --data-binary '$influx'"
}