my ($len, $string) = $s->read(9);
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 ) {
+ if ( $v[0] == 0xff && $sum == $checksum ) {
my $influx = "zph02,dc=trnjanska pm25_pcnt=$pcnt";
print "$influx\n";
system "curl --silent -XPOST '$influx_url' --data-binary '$influx'"