On Fri, 28 Feb 2014, Jonathan Leslie wrote:
> wait a sec, the resistor will fix the the 5v to 3.3 volt issue by limiting
> the current? I don't understand.
It's a common trick when interfacing 5v logic to 3.3v logic devices. Nearly
all devices have, effectively, forward diodes between inputs and the +power
line and a reverse diode to ground. By just using a resistor from a 5v
ouput to a 3.3 volt input you use the forward diode to the 3.3v supply to
clamp the output. See Tip #10 of Microchip's 3v Tips and tricks. A copy be
had at...
http://www.newark.com/pdfs/techarticles/microchip/3_3vto5vAnalogTipsnTricksBrchr.pdf
cheers
Jim
>
>
>
> >________________________________
> > From: Didier Juges <>
> >To:
> >Sent: Friday, February 28, 2014 3:08 PM
> >Subject: Re: [ts-7000] TTL serial on a TS7200
> >
> >
> >
> >
> >Be careful that some GPS modules output 5V TTL. That will fry rour TS-xxxx
> >in a hurry. I know that for a fact.
> >
> >
> >You do not need RS-232 level shifters, but you may need one to go from 5V to
> >3.3V. Usually, a 4.7k resistor in series with the Tx output of the GPS is
> >all you need. The input of the TS-xxxx will clamp at 3.3V and the resistor
> >will limit the current to a safe value. No need to do anything with the Tx
> >output of the TS-xxxx. The 5V device will accept 3.3V inputs just fine.
> >
> >
> >Didier
> >
> >
> >
> >
> >On Fri, Feb 28, 2014 at 9:46 AM, Jonathan Leslie <> wrote:
> >
> >
> >>
> >>I dont' know the ts7200 specifically, but the ts7500 you just solder onto
> >>the RX and GND pins to the gps modules TX and GND pins and you are hardware
> >>ready to go. The GPS module broadcasts 1 a second a dump at 4800 BPS.
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>>________________________________
> >>> From: Yan Seiner <>
> >>>To:
> >>>Sent: Friday, February 28, 2014 10:40 AM
> >>>Subject: [ts-7000] TTL serial on a TS7200
> >>>
> >>>
> >>>
> >>>
> >>>I have a TS7200 that I'd like to interface with a GPS module. Most of
> >>>the bare modules are TTL - 3.3 to 5V. Is there a way to set up a serial
> >>>port on the 7200 with ttl levels?
> >>>
> >>>I need RX, TX, and DCD pins active on the serial port for the GPS.
> >>>
> >>>
> >>>
> >
> >
> >
> >
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