msp430F5528: Max throughput of a SPI to USB bridge

Blake Carpenter

Part Number: MSP430F5528
Other Parts Discussed in Thread: MSP430USBDEVPACK

Hi,

I can run the numbers of max IO speed, SPI bus speed and theoretical USB Speed, but I was hoping someone could provide me with a max throughput speed I can expect with a 5528 doing nothing but moving data from USB to SPI. The customer wants to hit 5 mbit.

Full Speed USB should theoretically support 12mbit but with a 25mhz 430 clock, I was not sure we are even close to this theoretical...

e2e.ti.com/.../19746

This link above says worst case of approx 4mbit on the SPI. Can the 430 keep up moving data from the USB to the SPI at this throughput level - using DMA I assume?

Best Regards, Blake

over 8 years ago

0 Katie Pier over 8 years ago

TI__Guru* 77971 points

Hi Blake,

I'm going to look into this. I think 5Mbit is going to be tough to be honest. I think someone did some testing a while back on MSP430 USB throughput with DMA, so I'll try to see if I can find those numbers - that will at least give us the USB side of the equation.

Regards,
Katie

0 Blake Carpenter over 8 years ago in reply to Katie Pier

TI__Expert 7005 points

Thanks Katie!

I initially told the customer we couldn't get close, but then I found the SPI throughput numbers. The handoff between USB to SPI does sound too aggressive, but I would love to see if you can find some numbers.

Next week is fine.

Have a great weekend!

Blake

0 Katie Pier over 8 years ago in reply to Blake Carpenter

TI__Guru* 77971 points

Hi Blake,

I also agree with your first assessment (it's too aggressive) and now I found some results from some tests that back this up. Even with just the USB running in ideal conditions the throughput was nowhere near 12Mbit. So I don't think that is feasible even with 25MHz, DMA, etc.

Regards,
Katie

0 Katie Pier over 8 years ago in reply to Katie Pier

TI__Guru* 77971 points

For anyone coming across this later: there are some benchmarking results in MSP430USBDEVPACK in the file release_notes.html.
-Katie

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msp430F5528: Max throughput of a SPI to USB bridge