Re: [uCsimm] UART Hardware flow control.

From: David Williams (
Date: Thu Mar 30 2000 - 17:37:22 EST

Tom Walsh wrote:

> wrote:
>> As I know, uClinux (linux-2.0.38) verion seems not implement
>> UART hardware flow control for 68EZ328.
>> Does someone implemented it ??
>> Can I get the patch from somewhere ?
>> Or .. beside of specification of 68EZ328 user's manul,
>> where can I get the program guide for UART hardware flow control
>> for uClinux ?
>> Thank you very much!
>> Bobby Lai.
>> This message resent by the list server
> Flow control is a function of the hardware UART, check the users
> manual for the 68EZ328 and look over the section dealing with the UART
> for the programming details. There is no software intervention
> necessary to implement RTS / CTS flow.
> TomW

Only partially true. If CTS is enabled then the UART will manage this
for you stopping transmission whenever CTS is negated (HIGH). However to
get RTS to control flow in to the UART you must manage this yourself in
software. Ie when buffer gets close to full RTS must be negated (HIGH).
Remember that the levels mentioned here are at the microprocessor and
the RS-232 level are inverted (and magnified).

Dave Williams.

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