On Thu, 3 Apr 2025, Sam Sokolik wrote:
I thought this was fixed in the pid loop.. (I thought mesa had the same
problem)
The thing that's fixed in the PID loop is to avoid a massive
output spike due to the locally calculated DDT for FF1,FF2
when the position is set to zero on index detection. This
is why the PID component has a index-enable input pin.
Mesa encoders have never had a transient wrong count bug.
On Thu, Apr 3, 2025 at 2:15??PM Jon Elson <el...@pico-systems.com> wrote:
On 4/3/25 12:21, Jon Elson wrote:
> On 4/2/25 21:25, gene heskett wrote:
>>
>> That STG card sounds like magic. So the question is, does
>> anybody have the src code for that driver? Recompiling
>> it to run on arm64 might be an amazing thing. Professor
>> Bertho S. possible??? Or already done?
>>
>>
> The STG card is a full-length ISA card, so connecting to
> an ARM CPU might not be simple. The driver is in the git
> repository under:
>
>
https://github.com/LinuxCNC/linuxcnc/blob/master/src/hal/drivers/hal_stg.c
I have not looked at the stg code in 20 years, since I moved
to using my own hardware. Looking at the code, I do NOT see
the hack to detect and suppress large position jumps.
Without that hack, you have a significant chance of getting
following error trips any time the encoder passes through
the home position. Reading the code, it LOOKS like the
latch register is not used except during the home-to-index
operation. Reading the 24-bit encoder value a byte at a
time will have a possibility of catching registers during
the change. It seems that this could possibly happen at
other times, but I was able to catch it in Halscope back
when I was still using the STG back about Dec 2004.
Jon
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Peter Wallace
Mesa Electronics
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