[En-Nut-Discussion] UART Flow Control Broken?

Harald Kipp harald.kipp at egnite.de
Thu Aug 23 09:39:51 CEST 2012

Hi Ole,

On 22.08.2012 22:46, Ole Reinhardt wrote:
> I think his intention was to set the modeflags depending on the
> handshake mode given as parameter to the ioctrl and then call the
> dcb_set_flow_control accordingly. But as the modeflags contain many more
> flags beside of the flow-control, we should not pass them unfiltered to
> the dbc_set_flow_control, right?

Yes, but to make it clear: Flow control means both, hardware (RTS/CTS as well as DTR/DSR) _and_ software (XON/XOFF) handshake.

Actually, UART_SETFLOWCONTROL can be used to set all mode flags, including UART_SETHDPXMODE or the newly introduced USART_MF_BLOCKREAD/WRITE, which may be seen as flow control too.

> Sorry, I did not use it for a long time.

I'm trying to use a GPRS modem. It works fine without handshake, but I'm not sure, if missing handshake may be a problem in the field. Unfortunately removing the "if (bv)" part didn't fix my problems. It's Ethernut 3 and I'm not sure, whether this is a software or a CPLD problem. I'll need more time to evaluate this.



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