On Mon, 30 Mar 2020, Curtis Dutton wrote:
Date: Mon, 30 Mar 2020 16:33:13 -0400
From: Curtis Dutton <[email protected]>
Reply-To: EMC developers <[email protected]>
To: EMC developers <[email protected]>
Subject: [Emc-developers] Mesa Sigma5ABS module
Hi all,
I'm working out the design for the Yaskawa Sigma V absolute encoders.
Within hostmot2-firmware,
I've been studying the code and I'm not sure of the exact interface between
the mesa pci cards and linuxcnc.
It seems that the pci card is mapping registers into memory and that each
module is reserving a register address so that the hostmot2 driver knows
where to look for them to control them.
In IDROMConst.vhd, I'm looking for register address space to use. But I'm
getting the feeling that it is all used up. Perhaps that is the reason that
pkuart chose to use the same address's as the uart module.
The DPLLFreqLowAddr comments "note overlaps translate RAM" and "will fix in
the greate re-alignment"....
Does anyone know what the great re-alignment will be?
Can anyone shed some light on the addressing scheme used with the mesa
cards. Any other overview of how it works would be useful too.
At one time there was only 32K of useable address space because the EPP
interfaced cards used the MSB of the address as an address autoinc flag. Since
EPP interfaced cards are basically legacy devices at this point, newer hm2
modules use addresses > 0x7FFF and currently B000,C000,D000,E000,F000 are all
free.
At some point, complile time allocation of module addresses might make sense,
but that's a fairly large change so I think I'll wait until I run out of address
space until I do that.
Note, there's no harm in overlap as long as you dont expect to use the
overlapping modules in the same configuration
Thanks,
Curt
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Peter Wallace
Mesa Electronics
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