Hi Don
great to have your skills. they are ideal...
Agreed on the form factor. I liked the SM1000 idea. The question is do
we do a board that can fit in SM1000 case ? I'd like to. That solves the
problems for the ham without metalwork facilities.
The board will have headers for different IO. maybe I end up with a base
PCB and a mezzanine PCB on headers that has either a) a SM1000 /
discrete audio interface stuff, or (b) the digital radio interface. The
IO will be the same.....bunches of LVDS pairs, and some of the ADC pairs
bought up to the mezzanine.
VHDL yes. I have a commercial seat, maintained, of VHDL Modelsim... But
this does not stop anyone producing Synthesised Verilog modules and
including those into the block design in Vivado. Vivado is a bit of a
learning curve...
Ultimately on occassions, you do want to be able to support stand alone
debugging, since there are things that happen that are real time and
their behaviour is hard to emulate on a PC (but it is possible).
glen
On 20/07/2020 1:23 am, Don wrote:
There are two (at least) choices for the form factor and that will drive
a lot of the rest of the design.
1) A small box that a user can pick up and use as the microphone. This
limits the complexity (at reasonable build cost) and power dissipation.
It also limits the user interface quite a bit. The built in mic and
speaker will be rather limited too.
2) A small-ish box with connectors for the users choice of microphone and
speaker, or headset... This can be much larger that the first option
and still be easy to set on a desk or on top of a radio. It can
still be nearly instant on and avoid all of the problems people have
installing software on a desktop computer.
I'd like to second the suggestion of using a dedicated real time OS like
FreeRTOS, Chibios, etc. Maybe a very stripped down Linux would do as well
I have not worked with that. I don't think the box should support local
compiles or much stand-alone debugging. Build in an interface (Ethernet
or USB) and do those things on a desktop system.
I'd volunteer to help with the FPGA part, but I am afraid you will want to
use VHDL and all of my experience is with Verilog :-) . Seriously, I have
been wanting to do a Zynq project for quite a while and would be interested
in working on that. I could probably even learn VHDL. I have built
things like AXI bus interfaces, FIFO channels, and integrated DSP blocks.
Those were for image processing not audio but a lot should carry over.
I also agree with your comments about the current code being written
for development in a PC environment. Not a bad thing, just what it is.
There are many opportunities to streamline, reduce data size and copying,
etc. That is how we got 700D into the SM1000.
In my past work life we did 80% integer/fixed-point math and 10-15%
"pseudo FP". That took a lot more work up front to verify behavior against
the higher level models but there were also benefits. Besides smaller
implementations it is pretty easy to compare an integer implementation
to an integer model when you can expect an exact match bit for bit.
So verification and debugging in simulations or on hardware is a lot simpler.
Don Reid - W7DMR
Oregon, USA
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Glen English
RF Communications and Electronics Engineer
CORTEX RF
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Pacific Media Technologies Pty Ltd
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