BlueBill
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CTS, RTS & DTR in hardware?

Wed Nov 21, 2012 4:05 pm

Does the console serial port have CTS, RTS & DTR pins on the GPIO connector?
Bill

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tedhale
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Location: Williamsburg, VA, USA
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Re: CTS, RTS & DTR in hardware?

Wed Nov 21, 2012 4:09 pm

No. It has only TX and RX.
If you need hardware handshaking, you will have to use a USB-Serial adapter.
- Ted B. Hale
http://raspberrypihobbyist.blogspot.com

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jojopi
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Re: CTS, RTS & DTR in hardware?

Wed Nov 21, 2012 7:01 pm

You can configure CTS,RTS on GPIO30,31 (as alternate function 3). These signals are on the P5 header on a Rev2 board, but previously they were connected to the unused configuration resistors R3..R10 and would need some delicate soldering to access.

(RTS can also be configured on GPIO17, which is available on both boards, but GPIO16 is used for the status LED.)

DTR should be easy to implement in software.

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rew
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Re: CTS, RTS & DTR in hardware?

Sun Nov 25, 2012 8:23 pm

Anybody working on getting that going? What GPIO should I chose? Suggestions?
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dhbarr
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Joined: Fri Dec 28, 2012 4:30 pm

Re: CTS, RTS & DTR in hardware?

Fri Dec 28, 2012 9:10 pm

So I have an ST3232C, and I'm planning to hook it up as follows:

VCC <-- RED --> P1:02 ( 5V )
GND <-- BLK --> P1:06 ( GND )
TXD <-- BLU --> P1:08 ( GPIO14 )
RXD <-- YEL --> P1:10 ( GPIO15)
CTS <-- GRN --> P5:05 ( GPIO30 )
RTS <-- ORG --> P5:06 ( GPIO31 )

Does this seem essentially sane? Please be gentle, this is my first pi project :)
Cheers,
-dh.

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rew
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Re: CTS, RTS & DTR in hardware?

Sat Dec 29, 2012 8:23 am

Yes, that sounds very "sane": Those are the proper pins. You don't get much choice for RXD and TXD, and similarly, the other options for CTS and RTS are not available on headers, so 30/31 is a good choice.

Oh, and by the way: I've modified the driver to provide software-DTR. I've chosen DTR on GPIO 18 on my setup.

The code is up on github, I've posted a pull request, but so far nobody has responded. https://github.com/rewolff/linux

We needed that to allow "avrdude" to reset the AVR processor on the raspduino. Works like a champ!
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Re: CTS, RTS & DTR in hardware?

Thu Oct 02, 2014 11:37 pm

On Raspberry Pi model B+, there are GPIO 16 and 17 pins exposed at the GPIO pins which can be used as CTS and RTS respectively when switched to ALT3.

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