Pulse widths are 16us or greater.
I am using a custom bitfile. For the pins I wanted to
connect my AD7740's to, I changed the NullTag lines
to:
IOPortTag & x"00" & QCountTag & QCountQAPin, -- I/O 21
IOPortTag & x"01" & QCountTag & QCountQAPin, -- I/O 22
The encoder #0 and #1 pin A's show up when loading
linuxcnc. I also tried adding QCountQBPin's to unused I/O's,
but that did not make any difference. Do I need to have
index pins loaded too? I didn't get any errors from the
Xilinx tools (except the sim error at the end after bitstream
generation is finished).
I've posted my configuration at:
https://gab.wallawalla.edu/~ralph.stirling/projects/linuxcnc/2gbp
-- Ralph
________________________________________
From: Peter C. Wallace [p...@mesanet.com]
Sent: Thursday, January 14, 2021 9:59 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] measuring frequency with 7i90
On Thu, 14 Jan 2021, Ralph Stirling wrote:
> Date: Thu, 14 Jan 2021 17:40:51 +0000
> From: Ralph Stirling <ralph.stirl...@wallawalla.edu>
> Reply-To: "Enhanced Machine Controller (EMC)"
> <emc-users@lists.sourceforge.net>
> To: "emc-users@lists.sourceforge.net" <emc-users@lists.sourceforge.net>
> Subject: [Emc-users] measuring frequency with 7i90
>
> I am using an AD7740 voltage-to-frequency converter
> and Mesa 7i90 encoder input to measure an analog
> voltage. The AD7740 circuit is working ok, with a 0-100kHz
> pulse train output. I have the encoder function set to
> counter-mode 1, and have the pulse train connected
> to the encoder A input. I am not getting any velocity
> or counts though. Is there some additional step needed
> to enable frequency measurement? The encoder B input
> is not connected. I have tried it with and without hires-timestamp.
>
> Thanks,
> -- Ralph
That should work, in fact, thats how our THCAD for plasma works.
what is the pulse length? if the encoder filter is enabled
it will ignore the pulses if they are shorter than 15 encoder
sample periods (nominally 600 ns at the default 25 MHz
encoder sample rate)
>
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Peter Wallace
Mesa Electronics
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