On March 12, 2017 5:31:42 AM MDT, MH <mhemc2nos...@googlemail.com> wrote:
>
>Hello,
>
>I have a question about the behaviour of the halui bit pins and would
>like to confirm that I understand the code correctly. I could not
>answer
>my question from the halui documentation.
>
>Do these pins activate on both a rising and a falling edge ?
>
>It like to use the input pin halui.program.pause to pause a running
>program if I get a signal that might indicate that the material sheet
>*might* have moved and the operator needs to check.
>
>Having a cursory look at the linuxcnc source code I suspect the halui
>pins come from linuxcnc-dev/src/emc/usr_intf/halui.cc
>
>And in halui.cc these line (with lines numbers):
>
> 1114 static int sendProgramPause()
> 1115 {
> 1116 EMC_TASK_PLAN_PAUSE emc_task_plan_pause_msg;
> 1117
> 1118 return emcCommandSend(emc_task_plan_pause_msg);
>
>...
>
> 1544 static int check_bit_changed(bool halpin, bool &newpin)
> 1545 {
> 1546 if (halpin != newpin) {
> 1547 newpin = halpin;
> 1548 return halpin;
> 1549 }
> 1550 return 0;
> 1551 }
>
>...
>
> 1654 if (check_bit_changed(new_halui_data.program_pause,
>old_halui_data.program_pause) != 0)
> 1655 sendProgramPause();
>
>That line 1654 looks to me as if both edges would trigger the msg
>emc_task_plan_pause_msg to be send.
>
>Is that correct ?
Almost. Look at line 1548, if the pin has switched state it turns the new
state. So that function returns True on a positive edge, only.
I notice now that the names of the variables inside the function are the
opposite of what it seems they should be, that's confusing...
--
Sebastian Kuzminsky
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