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ziutek / ftdi

Go binding for libFTDI
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Added in MPSSE constants for SPI bus support #22

Closed AndreRenaud closed 2 years ago

AndreRenaud commented 2 years ago

These are from https://www.intra2net.com/en/developer/libftdi/documentation/ftdi_8h_source.html#l00100

ziutek commented 2 years ago

Looking quickly didn't find information about MPSSEDivValue. What is this function for? Where the calculated value is used?

AndreRenaud commented 2 years ago

It's used to construct the value to pass as the clock divisor after MPSSETCKDivisor. However I've just done a minimal transfer of the C Macro, and to be honest it's pretty useless (both the macro and the function I've created). The return value is only usable as two bytes, so you always need to cast it. And it only copes with the 60MHz clock, so if you've set MPSSEEnableDiv5 then it is of no help at all. It's a trade off between maintaining a very thin wrapper on top of libftdi and providing something a little more functional - I went with the thinnest of wrappers. I could add some explanatory comments to it though?

ziutek commented 2 years ago

Yes, a comment will be useful. Even some hardware SPI example in examples directory would be nice.

I'm personally interested in this topic because I plan to use the fast FT2232H SPI in near future instead of slow bitbanged one with FT232R. It would be a pleasant surprise to see how it works with this package.

AndreRenaud commented 2 years ago

I'm out-of-office for a bit, so have no access to hardware to confirm. However I've put together what I think is a working reference example. I'll double-check it on actual hardware later in the week and update this PR then.

ziutek commented 2 years ago

Ok. Thanks!

AndreRenaud commented 2 years ago

Ok - this example now works (confirmed the signals on a scope). It doesn't show how to do reads, just writes, but hopefully gives a head start on people trying to use MPSSE/SPI on the FT4232H & FT2232H families.

I've used this library to successfully talk to various SPI chips on a custom PCB - thanks for writing this.

ziutek commented 2 years ago

Thanks! Especially for the example code.