Re: configuring an Efinix T20

On Sat, 7 Sep 2024 19:29:41 +0100, John R Walliker
<jrwalliker@gmail.com> wrote:

On 07/09/2024 16:58, john larkin wrote:

On Sat, 7 Sep 2024 15:19:59 +0100, John R Walliker
<jrwalliker@gmail.com> wrote:
 

On 06/09/2024 23:50, john larkin wrote:

>
I'm planning to use a Raspberry Pi RP2040 processor chip to configure
and then talk to an Efinix T20-FG256 FPGA.
>
Has anyone done this, or at least configured a T20 from a
microprocessor?
>
The RP2040 only has 30 GPIO pins, and many are dedicated to other
stuff, so we want to share a lot of things on one giant SPI bus,
including the FPGA config and then an SPI port on the FPGA to read and
write registers.
>
It looks like four of the T20 config pins need pullups. I wonder why
their guidelines show four separate resistors. Why not one resistor?
Why have resistors at all?
>
SS_N needs a pulldown. Why not ground it?
>
https://www.dropbox.com/scl/fi/x0gvvwqg42vhryu6610ve/Efinix_Config_1.jpg?rlkey=udy24brtumvdzfd2sp4l6yhwf&raw=1
>
>
It's always a moment to celebrate when a "config done" LED lights up.
>
I could easily get this wrong, so it would be great if I posted some
schematics and notes and someone could eyeball them for me.

>
If you need some more i/o pins, why not use the RP2350B?  They
definitely exist - I have one in front of me:
https://shop.pimoroni.com/products/pga2350?variant=42092629229651
>
John

 
It only has two more package pins, as I recall. How many GPIOs?

>
No.  The RP2354B has 24 more package pins and 18 more GPIOs than
the RP2040.
>
Its an 80-pin package with 48 GPIOs.

I was thinking about the RP2350, which has 60 pins. That's the chip on
the Pico 2.

I didn't even know that there was another small chip, the 2354B. That
might be the next step for our product line, in a year or two after
the new chips are debugged and available in quantity.

The 2350 data sheet is 1349 pages, possibly a world record.

I can't immediately find a data sheet for the 2354B.

>

It's new and a bit buggy and not widely available, so we'll stick with
the 2040. The only upsides are the higher clock rate and the faster
floats, which aren't critical in the product line that we are
developing now.

>
Yes, there are some bugs.  The most critical is probably the one
relating to on-chip pull-downs, but it can be solved with external
resistors.  The ADC is improved.  There are more and better
i/o state machines.  There is a lot more on-chip RAM and there
will soon be the option of flash in the same package.
There may not be production quantities of the RP2354B readily
available yet, but there are certainly some around for prototypes.
As I mentioned, I have one.

Does the 2350 have a switching regulator on-chip? Microns away from
the ADC?