PJE,
Thanks for the info. I'd be really curious about using the x4
counting, I'd be interested in learning how one would modify the FPGA
to accomodate this.
I've been using a similar approach for calculating the velocity. I'm
using the TC4 debug 4-bit timer as well. 983.04 kHz is what I read as
well. Unfortunately, I am not calculating RPM's correctly using this
appraoch. At least I this is what I think. I am verifying my
calculated velocity by measuring rotation with a non-contact optical
tachometer. Unfortunately, our encoder onlyhas 64 ticks per rev and
this is challenging to accurately calculate a velocity from.
Did you perform any verifications on the T4 clock to ensure that your
timings are accurate/consistent? Did you develop a kernel module or
user space program to perform the velocity calculations.
Our project is for a commercial application, so we may not be able to
use your code. I may be over simplifying thigs, but it should be
fairly straightforward to go from a x1 counter to a x4 counter.
-Ira.
--- In "PeterElliot" <> wrote:
>
> Hi Ira,
>
> I'm using the quadrature for monitoring multiple servo drives. For
> our application we're soon to be getting Technologic Systems to
> create a custom FPGA module for the TS-7300 which will enable four
> 2048 line encoders to be monitored. I'm likely to be adding X4
> counting as an option as well as a revolutions and position within
> revolution mode when used with an index pulse.
>
> This module is being set to capture the encoder reading into a FIFO
> buffer at a preset rate (normally between 1 and 10kHz). The velocity
> is then proportional to the counts between consecutive readings. I'm
> considering having velocity generated in the FPGA, but so far it
> seems fine calculated by the main CPU if the samples are taken with
> an accurate clock.
>
> At present I've been reading the TC4 counter (983.04kHz? clock)
> repeatedly after a trigger condition and then every 983 counts
> reading the XDIO quadrature, which produces reasonable results but is
> not a viable method for the finished system.
>
> If your application is non-commercial I might let you use our FPGA
> code in your application.
>
> Regards,
>
> PJE
>
> --- In "drrock77" <ihoffman@> wrote:
> >
> > All,
> >
> > Is there a way to perform 4x quadrature counting using the TS-7x00
> > XDIO interfaces? It seems that the XDIO quad counter is only a 1x
> quad
> > counter. We are using a fixed gear with Hall Effect Sensor that has
> 64
> > teeth. We need better resolution, and are unable to change the gear.
> > Any ideas?
> >
> > Is there a way to generate and handle an interrupt for each counter
> > change and perform a delta time using the high res timer?
> >
> > It'd be great to be able tp pick someone's brain who has used quad
> > counting for odometry.
> >
> > Thanks,
> > Ira
> >
>
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