Yes, it looks like Albert's CTS reset circuit, but applied to RTS (cap)

Seb



2009/8/14 funlw65 <[email protected]>

>
> Look at Sanguino schematic, maybe helps:
> http://sanguino.cc/hardware
>
> On Aug 13, 10:47 pm, Sebastien Lelong <[email protected]>
> wrote:
> > Hi Albert,
> >
> > Thanks for your suggestion, but Tiny software requires to reset via RTS,
> not
> > CTS.
> > Anyway, do you have a link with a schematic for what you describe ? (just
> to
> > make sure I understand clearly what you say)
> >
> > Cheers,
> > Seb
> > --
> > Sébastien Lelonghttp://www.sirloon.nethttp://sirbot.org
> >
> > 2009/8/13 a.faber <[email protected]>
> >
> >
> >
> > > Hi Seb,
> > > Mostly I used a simple but effective reset circuit, just connect the
> CTS
> > > line with a 10uF capacitor  with the reset line (and using a diode +
> 10K
> > > resistor to pull up the reset line). The cap only initiates a pulse
> when
> > > the
> > > CTS line is changed from high to low, the reset line will be pulled
> high
> > > after a couple of milliseconds even when the CTS line stays low.
> > > Albert
> >
> > > ----- Original Message -----
> > > From: "Sebastien Lelong" <[email protected]>
> > > To: <[email protected]>
> > > Sent: Thursday, August 13, 2009 9:00 PM
> > > Subject: [jallib] Re: jaluino (resetting via RTS)
> >
> > > I tried to prototype the "reset using RTS" thing on a breadboard, but I
> got
> > > troubles (as expected...). I followed the schematic and connected D2,
> R2,
> > > R3
> > > and Q1 onto the breadboard.
> >
> > > It's as though it's acting the reverse: when I plug the serial module,
> it
> > > keeps resetting the PIC.
> >
> > > When I plug the serial module:
> > >  - Vrts ~ 4.1V (5V without hardware D2, R2, ...)
> > >  - PIC doesn't blink the LED (keeps resetting)
> >
> > > For my tests, I used python serial module:
> >
> > >   import serial
> > >   ser = serial.Serial(port="/dev/ttyUSB0",baudrate=115200)
> >
> > > by default, when the serial connection is created by this command, RTS
> = 1,
> > > and Vrts ~ 0V. The PICs starts !
> >
> > >   ser.setRTS(1)  -- will reset the PIC, Vrts ~ 4.1V
> > >   ser.setRTS(0)  -- will start the PIC, Vrts ~ 0V
> >
> > > So, it seems to work but on the contrary expected behavior. I would
> expect
> > > that by default the PIC starts.
> >
> > > Does it seem weird to you too ? Or did I miss something ?
> >
> > > Cheers,
> > > Seb
> >
> > > > > > Also ask by Seb is the reset option by RTS (J7).
> >
> > > > > OK this is where I'm lost... I have few questions about this:
> >
> > > > >   - RTS and CTS in serial connector are connected to RD5 and RD4.
> Why ?
> >
> > > > If you want handshake you can use RD5 and RD4, if you dont need
> > > > handshake you
> > > > Can use RD4 and RD5 on connected I/O4
> >
> > > > >   - when I want to reset the board using RTS, I need to switch RTS
> J7
> > > > > trigger to position 1-2, as in the schematic. Is that right ?
> >
> > > > Yes, if you put it in position 2-3 you cant use reset but you can use
> > > > handshake.
> > > > If I did not use the switch (is jumper) than you could not use RD4 as
> > > > normal I/O
> > > > because PIC would reset as soon as RD4 becomes high.
> >
> > > > >   - All the serial modules I've used or built have their RTS
> connected
> > > > > to
> > > > > CTS. No flow control, quite common I think. Like in this article:
> > > >http://www.lynxmotion.com/images/html/build125.htm. Now imagine I use
> > > such
> > > > > a module with RTS and CTS connected. I plug it to the board. Will
> this
> > > > work
> > > > > ? Or should RTS and CTS remain unconnected from each other ? In
> that
> > > > case,
> > > > > do I have to deal with flow control ? (hope not...)
> >
> > > > Yes this will work and No you dont need flow control, but like in
> > > > your link dont connect the RTS end CTS from the serial module to the
> > > > serial connector of the Main Board else you cant use RD4 and RD5 for
> > > > other purpose.
> >
>

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