[hpsdr] New Hermes 2M Board.

[John Marvin]

On 5/28/2017 1:33 PM, Kjell Karlsen wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> 6 New FPGA. Phil, VK6PH is looking for a more modern FPGA to replace the
> Cyclone III that is used today

....
>
> When the construction is tested and found OK, we can make a list and
> produce fully populated and tested boards. Also bare boards will be
> offered for the brave ones.
>
1) Could we drop the requirement that the FPGA not be a BGA version? I 
know that means that people who want to assemble their own boards would 
have to be really really brave :), but it opens so many more options, 
and the number of people who want to build their own are significantly 
in the minority.

I'd like to see the board laid out for a BGA FPGA. Pick a family of 
FPGA's that are pin compatible but have a large range of capacities.  
Then when people reserve a board they can pick which size FPGA they want 
to have, and as long as there are enough people at each size, we can 
have runs done for multiple FPGA sizes, but everything else being the 
same. The people testing/writing the FPGA code can choose one particular 
size to test / develop on, and they can make that size known in advance, 
for those who want to make sure they get the "supported" size. People 
who have the other sizes can get the base firmware, change a few 
parameters and build a version that supports their larger capacity board 
without having to know much of anything about FPGA programming, i.e. 
just enough to run the tools (of course they could run into timing 
closure issues). My FPGA skills are fairly weak, but I would certainly 
be willing to create new Hermes FPGA's for at least whatever size I buy 
and make it available to others, given a release of the RTL code for the 
"supported" size.

For example, we could choose the Cyclone V E FPGA family in the 484 pin 
BGA package.  Using the 484 pin package allows the full range of Cyclone 
V E FPGA capacity to be available. The cheapest FPGA's within that 
package are the one's with no hard PCIe controller or hard memory 
controller, with the slowest fabric speed grade of "8". That allows for  
5 pin compatible FPGA's:


Product Code    LE's   Price
     5CEBA2F23C8N     25   $37.76
     5CEBA4F23C8N     49   $53.30
     5CEBA5F23C8N     77   $88.04
     5CEBA7F23C8N    150  $159.36
     5CEBA9F23C8N    301  $209.76

The A4 variant is about equivalent (slightly better) to the size of the 
Cyclone 3 FPGA used on the current Hermes board, so perhaps we shouldn't 
offer the A2 variant at all.  The prices are single quantity Digi-Key 
prices, are are presented purely to give an idea of relative pricing vs. 
size.  Perhaps to keep it simple some options might be eliminated, e.g. 
perhaps only the A5 and A9 variants, i.e. "better than Hermes", or 
"max". Anyway, this is just an example of what I am suggesting.

I for one would like a newer generation Hermes with a much larger 
capacity (at least enough capacity to run one receiver slice on every 
ham band at the same time), but I don't think that should be done by 
forcing everyone to pay an additional $100-$200 for the largest capacity 
FPGA.

2) Either make sure the new power regulators can handle powering the 
largest possible FPGA, or at least continue to make it possible to 
bypass the SMPSU(s) if necessary (i.e. I don't mind still needing to 
provide external regulated power for 5V and 3.3V if it is required for 
those who want the largest possible FPGA capacity).

3) Although I think it's great that other boards may be done that will 
be compatible with the new Hermes, but please make sure that the new 
Hermes remains completely independent like the old one, in order to 
maximize flexibility. My Hermes is the only OpenHPSDR board in my 
current setup.

4) Consider taking the ACC port connector off of the edge and placing it 
on the top or bottom of the board. Many people don't use the features on 
this board, or if they do, they could bring it out with an internal 
connector wired to an external connector on their custom chassis as they 
see fit.  This would leave more space available for other feature / 
external connector alternatives.

5) If there is any thought of adding a second ADC, please make that an 
alternate fill option (possibly requiring those who want it to exercise 
their SMD soldering skills). My guess is that a majority of people don't 
care for the extra expense for a feature they have no plans to use.

6) Try to keep the budget for the final production board relatively 
close to the previous Hermes price, at least with the smallest supported 
FPGA (still that should be >= current Hermes capacity).

73,

John
AC0ZG
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