On 8/17/24 04:47, Marc Schink wrote:
I would imagine many embedded developers have a PCI or PCIe
serial+parallel card laying around. You never know when it might be
useful. I personally have like 3.
Can you provide me the names of your parallel port interface cards?
What mode (i.e SPP, ECP, EPP) must be supported for OpenOCD? USB-based
parallel port adapters do not work at all, right?
I have one of the Oxford OX16PCI954 (conventional PCI) quad UART +
parallel port cards that Michael Schwingen mentioned as well as a
"Nanjing Qinheng Microelectronics Co., Ltd. Device 3250" PCI IDs
1c00:3250 (PCI Express). Both seem to work in Linux with the usual
parport_serial driver without any extra fuss.
I couldn't find my third one - it's around here somewhere. It's a
different model PCIe card. It uses the same parport_serial driver under
Linux. They all basically just clone the classic PC parallel port IO
address set and place it somewhere else in the IO space using PCI IO
addressing.
I only expect bit banged operation using SPP. I don't have any "smart"
parallel port adapters at this point. There's not much reason for them
IMO given that you can do the same thing with a lot more convenience
over USB. The usefulness of a parallel port "adapter" is the ability to
whip one up at the bench in 10 minutes with nothing but some connectors,
wire, maybe some resistors or diodes, and a soldering iron - i.e. all
stuff you could easily have laying around.
Getting USB parports to work would be useful in that regard, but I don't
expect it. The timing and configurability of a typical USB parallel
adapter just isn't predictable (enough). They were all intended to run
printers and nothing more. I know some of them don't even support bit
twiddling of the handshaking lines and implement all of the handshakes
in hardware from a data FIFO making them fundamentally incompatible with
bit-banging serial protocols.
--
Brandon Martin
