Lpc2000

At 04:47 PM 4/22/05 +0100, Robert Wood wrote:
>I'm setting up comms between an LPC2194 and an FTDI USB chip. It would
>appear that the CTS of the LPC can be connected to the RTS of the FTDI
>device as the FTDI device sets its RTS high when its receive buffer only
>has 32bytes of space left in it. It can thus tell the LPC to stop
>transmitting and it seems that taking the CTS line high on the LPC will,
>indeed, stop the LPC from sending data out.
>
>So, it looks like the RTS of the FTDI chip is really a ready to receive
>signal.
>
>However, it looks like the RTS on the LPC is not quite the same. It
>seems that it really is a request to send, rather than a ready to
>receive signal. The closest pin I can find would seem to be DTR, but I
>don't think it's the same thing at all.
>
>Do I understand correctly? Does the LPC simply not have a pin that can
>drive an external device to tell that external device that it [the
>external device] may send data into the UART of the LPC?

I think you are expecting too much of the UART.  As I recall the pins are 
assigned there function by convention only.  You can make them mean 
anything you want them to.  They are controlled strictly by software not by 
the HW.

As a side note, strictly speaking the pins are not defined as flow control 
pins.  They are used that way frequently though and the 232 interface long 
ago lost its connection to the standard definition.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
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