Messages in this thread | | | Date | Tue, 23 Mar 2004 10:31:02 +0000 | From | Russell King <> | Subject | Re: synchronous serial port communication (16550A) |
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On Tue, Mar 23, 2004 at 11:09:33AM +0100, Christof wrote: > To make the story short: I see a lot of garbage on the LCD. > It looks like output would be buffered and all data would be sent at > once without giving me the possibility to check if everything's > allright. Sometimes I can send >400 Bytes and ioctl says that CTS is not > asserted, altough it certainly is.
It probably isn't, at the time you check it. When you write a byte, the call will generally return immediately because it'll be placed in a buffer. Transmission has only just started, and you then go and check the CTS line. Repeat multiple times on a slow enough baud rate, and you'll end up queueing a lot of bytes.
You could write a byte, wait for it to complete by calling ioctl(TCSETSW) without changing any parameters, and then read the CTS status.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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