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Re^2: i2c bus contention

by anita2R (Scribe)
on Mar 30, 2020 at 13:07 UTC ( #11114796=note: print w/replies, xml ) Need Help??


in reply to Re: i2c bus contention
in thread i2c bus contention

@GrandFather I would rather not combine my scripts, as they each have very different purposes, and the two scripts are also used independently on other machines. I think that creating a daemon is worth a try. As I have no formal IT training, this is going to be an interesting learning experience.

As to the common module with a lock file, I am still stuck with how to have two scripts accessing a common module. I have now tried running a script that has package functions and calls the two test scripts. Pretty messy to put it mildly, but is was just an experiment.

#!/usr/bin/perl package Hvac::i2cAccess; use strict; use HiPi::Device::I2C; use Exporter qw( import ); our @EXPORT_OK = qw( i2c_test1 i2c_test2 ); my $copyit = "Empty"; # call test scripts # test1 just gets the $copyit value # test2 sends an i2c object and gets the voltage value in return # the voltage value is also copied into $copyit do "/home/huw/cron_scripts/test1.pl"; print "A\n"; do "/home/huw/cron_scripts/test2.pl"; print "B\n"; do "/home/huw/cron_scripts/test1.pl"; print "C\n"; while( 1 ){ sleep 1; } exit 0; # ********************************************************* # sub i2c_test2 { # i2c object passed from test2.pl my $obj = $_[0]; # read 2 bytes of data from bus voltage register (address 0x02) my @bvr; eval{ @bvr = $obj->bus_read( 0x02, 2 ); 1; } or do { $bvr[0] = 0; $bvr[1] = 0; }; # result in upper 13 bits - big-endian order my $busV = pack 'C2', $bvr[0], $bvr[1]; $busV = ( unpack 'S>', $busV ) >> 3; # scale bus voltage register value my $bv = 16; my $bvScale = 4000; $busV = $bv / $bvScale * $busV; $copyit = $busV; return $copyit; } # ********************************************************* # sub i2c_test1 { print "Test 1 subroutine\n"; return "Copy $copyit"; } # ********************************************************* # # must end modules with a 'true' value 1;

but I don't get past the first 'do'. I presume that 'do' is waiting for the script it calls to end and return a value. 'A' is never printed

The module code without the 'calls' to the two test scripts was used to test the common module approach, but as I said, it looks like each test script invokes a separate copy of the module.

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