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Re: [bluetooth-dev] Large file transfert with CSR and BCSP



> ... But sometime, the link is stopped, even with BCSP. :-(
> I don't understand why, as I was thinking the BCSP protocol is for
> having a reliable connection. After the tests I have done, I agree the
> BCSP link is a lot more reliable than with H4, but not enough to have a
> safe link.

Check that you are using CRCs with BCSP. The host controller can be
configured to send them or omit them. Sometimes devices are shipped with
CRCs turned off. If you read the persistent store key
HOSTIO_UART_PS_BLOCK ("UART settings block", 0x0191) and look at the
sixth word, it's a boolean controlling whether the host controller will
send CRCs. If it's set to 0 then set it to 1 and try again. If you access
it through key 0x0191 then make sure you write the rest of the words back
correctly.

If you're using a CSR tool to alter persistent store then there's
a single word alias to the same control. It's called UART_USE_CRC_ON_TX
("UART: CRCs used on BCSP tx?", 0x0408).

Obviously, this will make a difference only if the host stack is
checking the CRCs. You should also make sure that the host stack is
appending the CRCs when it sends data to the host controller.

Without CRCs, BCSP will detect just parity and framing errors. So
it should still be noticeably better than H4, however, with CRCs
it should be better still. My guess is it's the framing errors
(probably due to the host UART discarding bytes due to FIFO overruns
or parity errors) that are giving the 'Incorrect length, discarding
data' error message.

If you're still having problems then try to get a trace of the bytes
being sent over the UART. You want to get the data in both directions
just before the crash. Probably the last 10k each way is sufficient,
but the more the merrier.

Out of interest, can you tell me which CSR firmware version you're
using as reported by HCI_Read_Local_Version_Information?

	- Steven


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