Re: UART
Kurt Harders wrote:
How does the UART know that the device connected to it is ready to
receive data?
It does not know anything about the connected device. The driver may
look at the handshake lines (DTR, RTS, CTS...) but thats not part of
the UART.
A lot of the time those handshaking signals run across the same chip
where the UART function is found. But it's true that simple UART need
not pay attention to them - they would merely show up in registers the
host CPU could access.
With buffered UARTs though, the buffering will not do much good in a
handshaked application unless the control circuit for the buffers
monitors and drives the handshaking signals. You could of course argue
that a buffered UART is simply a dumb UART surrounded by a buffer and
it's controller, and argue that the buffer and it's controller are
merely part of a driver transformed into hardware.
.
Relevant Pages
- Re: Serial driver hangs
... > UART in that case and throw them away. ... > there could be enough place in the other flip buffer. ... The driver usually calls tty_flip_buffer_push at ...
(Linux-Kernel) - Re: Thorny Serial Comms "UART: Overrun" error Windows CE 5.0
... Has OpenNETCF helped you? ... > a) Try and get hardware handshaking to work. ... >> Do you know if it's the UART's FIFO buffer or the Serial Driver's ... >> If it's the Serial Driver's buffer that overruns, ...
(microsoft.public.windowsce.platbuilder) - Re: Linux serial port dropping bytes
... UART is on a slow bus, you should be able to read out characters ... interrupt itself - context switches, cache misses, etc. That's ... why you use a UART with a buffer - it takes virtually the same ...
(comp.arch.embedded) - Re: Thorny Serial Comms "UART: Overrun" error Windows CE 5.0
... in my case I am actually looping back from one COM port ... I don't know if it is the serial driver or the UART. ... errorFlags has the OVERRUN bit set. ... > Do you know if it's the UART's FIFO buffer or the Serial Driver's ...
(microsoft.public.windowsce.platbuilder) - Re: Interrupt driven UART
... is why I think I have to use interrupt driven UART rather than polling ... receivebyte seems to be pretty redundant. ... rx ready flag is set, after which it just clears it. ... consider using a ringbuffer aka 'circular buffer' aka fifo for this. ...
(comp.arch.embedded) |
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