[Oberon] FTDI chips on Oberon boards

[Magnus Karlsson]

Wojtek,

Pepino, Pipistrello and Papilio Duo use FT2232H which is a high-speed 
(480 Mb/s USB transfer rate) device, while Papilio One and Papilio Pro 
use FT2232D which is a full-speed (12 Mb/s) device.  OberonStation does 
not have USB support so no FTDI chip on board (you have to use and 
external JTAG programmer if you want to reprogram the FPGA).

FT2232D and FT2232H are similar but quite different.  Both have two user 
ports but FT2232H has significantly more capabilities in addition to 
being a much faster part.  FT2232D can only do JTAG on port A while 
FT2232H can do JTAG on both port A and port B.  Both parts can do 
parallel I/O (like FT245 async FIFO mode) but only FT2232H can do 
synchronous FIFO mode (on port A) at speed up to about 30 MB/s sustained 
data transfer rate.  FT2232D is limited to about 1 MB/s in async FIFO 
mode while async FIFO on FT2232H can do about 8 MB/s.

The FT2232D and FT2232H data sheets from FTDI has many examples on how 
to connect the parts in different configurations (JTAG, UART, FIFO etc.).

Most JTAG programming software that supports FT2232D/H assume that JTAG 
is on port A (since FT2232D only supports JTAG on port A) so I would 
recommend using port A for JTAG on FT2232H as well.  The drawback is 
that this will make the sync FIFO interface unavailable since it only 
exists on port A.

>> I wonder which of these three designs is the most valuable for copying?

While Papilio, Pepino and Pipistrello all have JTAG on port A, only 
Pipstrello has the full hookup of port B so that it can be used for 
async FIFO mode.  If you need sync FIFO mode speed then just swap the 
port A and port B hookup but understand that JTAG on port B might not be 
supported by the JTAG programming software (fpgaprog does).

>> Is any other FW/SW reference design available for reusing the Pipistrello FT2232H connections?

Send me an email about what you need and I will put something together.

Magnus


On 3/31/2017 8:56 PM, Skulski, Wojciech wrote:
> Hello:
>
>    I am looking for some clarification concerning the FTDI chips on Papilio, Pepino, Pipistrello, and OberonStation. (Is the OberonStation schematic available?) The first three boards use FT2232x, where x=D or H. In all three cases the FPGA JTAG is connected the same way, but the serial port is connected differently. I would like to copy one of these designs in order to use the same software drivers for the FTDI chip (fpgaprog, for example, but also the serial ond possibly fast parallel transfer).
>
> I wonder which of these three designs is the most valuable for copying?
>
> I am tempted to reuse the Pipistrello connections, if the firmware and software is available for the fast parallel transfers over the BDBUS (FT2232H pins 38-46). I guess this is called "fifo interface mode". How difficult would it be to extract these pieces from the OpenBench Logic Sniffer? Is any other FW/SW reference design available for reusing the Pipistrello FT2232H connections?
>
> Thank you,
> Wojtek
>
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