USB Interface Chip Vs FPGA Implementation

Hello all,

We are trying to decide whether or not to purchase a cheap USB host controller to handle a single peripheral device or setup a Spartan 3E 500 gate FPGA to act as the host.

.. we are relatively sure that trying to implement Host code on a spartan

3E is a terrible idea... but cannot actually confirm why other than common sense.

Could you guys help us out with some reasons why the dedicated host chip or FPGA solution might be better? (code or physical layout might be too difficult?)

Thanks in advance

khex

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Reply to
khex
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n

or

Isn't this answered by the cost of the FPGA resource ?

If half the device is sitting there unused, and the project worries more about final cost than engineering time, then a FPGA USB is a good fit.

Conversely, if the FPGA is ~full, and adding USB bumps you up to be next device, then it is expensive. Likewise if your project worries more about completion time, than parts costs.

-jg

Reply to
-jg

I'd say go for an external controller chip, unless you are in for the educational experience of designing one.

Writing the code (driver + stack) to talk to a device through an external chip already amounts for quite a challenge. Also, I'd consider it a helpful prerequisite before rolling your own fully custom controller.

Reply to
Marc Jet

n

or

USB host is mostly about software, the hardware isn't too much different, but there is a lot of s/w involved, especially once you start pulling in drivers for things like the HID class. You might be better served using something like a cpu module that gives you a whole cpu-memory-usb complex and has the code done, then implementing your special stuff in the FPGA.

Reply to
Andy

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mon

p or

I'm sure if you only have to support one specific device you could make a lot of short cuts with the fpga implementation, with the external host chip that might not be so easy, but it will most definitely take more time to get it to work

-Lasse

Reply to
langwadt
2010-11-16 04:14, khex skrev:

Why not get a Microcontroller with USB host? You can either use it as the main processor, or as an auxiliary processor which will handle the USB protocol fully. That is what the "cheap hosts" are doing, but this gives you more flexibility.

Best Regards Ulf Samuelsson

Reply to
Ulf Samuelsson

That's cool that people can get the loan moreover, it opens up new opportunities.

Reply to
WISENINA22

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