wow. neat trick. thanks all who answered. so the operating instructions are:
for low bandwidth pulsed signals (under 9600bps) putting a 4.7k resistor inline
is a poor-man's voltage converter.
so if you had a gpio pin and a 5v supply with a 4.7k resistor in line, this
would not work because the 100% duty cycle 5v input would burn out the diode
correct?
>________________________________
> From: Jim Jackson <>
>To: "" <>
>Sent: Friday, February 28, 2014 5:52 PM
>Subject: Re: [ts-7000] TTL serial on a TS7200
>
>
>
>
>
>
>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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