The 7200 has one fully functional serial port, with an SP213 charge pump
chip (similar to a max232).
So I can't plug that into a TTL GPS module without toasting the module.
I have a max232 adapter with 6 pins that I can use. I was just hoping
to be able to get a software serial port on one of the 5v headers....
Oh well, complexity wins the day. :)
--Yan
On 02/28/2014 02:24 PM, Didier Juges wrote:
All CMOS chips (like the processor on all TS-xxx) have small diodes on
all inputs that clamp the voltage on that input so that the voltage
cannot go much above the positive rail of under the negative rail
(usually ground). These diodes are not discrete parts that are
installed on purpose, they are a result of the CMOS fabrication
process. These junctions are very small and have very limited current
capacity, so if you connect an input of such a chip to a stiff source
that is higher than the chip's supply voltage, the diode will blow,
usually causing other damage inside the chip. However, if you drive
for instance an input of a 3.3V powered chip from another chip that
may be 5V powered through a resistor of 1 to a few kOhm, the resistor
will limit the current to a safe value.
I do that routinely. It is particularly effective when the signal is
relatively slow (like the serial data from a GPS receiver) because the
resistor has the side effect of slowing the edges of the signal, and
you could not properly transfer data a 1Mbit/s that way, but for 4800
or 9600 bauds, it is fine.
Didier
On Fri, Feb 28, 2014 at 2:21 PM, 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.
------------------------------------------------------------------------
*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.
|