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Help me make a UART serial communication between the PC and EMX Development System


#1

Hello I have a map EMX development system I want to make communication between the PC and EMX SYSTEM DEVELOPMENT
I made a program that send characters from EMX Development System to the PC through the com2
the question:
is that I need a circuit MX 232 (TTL TO RS232) or not ?
Knowing that I measured the output com PC (-12v, +12v) and EMX Development System (-5v, +5v) (the sorites TX com 2)
My EMX development system:
https://www.ghielectronics.com/catalog/product/129


#2

Simplest way is to use a FTDI cable.

http://uk.farnell.com/ftdi/ttl-232r-3v3/cable-usb-to-ttl-level-serial-conv/dp/1329311


#3

MY QUESTION
is that the communication in the PC and DS EMX is feasible with RS 232 cable
connect directly


#4

my PC have a port COM


#5

I would not recommend to connect it directly. As you measured, PC is standard RS232 12V and EMX is TTL level (5V, or even 3.3V!?)
There is a n extra RS232 module available, which does the voltage level adjustment (and has a standard 9pin DSub connector:
https://www.ghielectronics.com/catalog/product/355
If you go to the resources tab -> schematics, you can see what this modules does.
It’s just a ST3222ETSSOP plus some additional passive elements.
You could also use a USB, serial module, by this you don’t need RS232 on PC side, which is quite rare nowadays.
On SW side it’s exactly the same.
COM (UART) on EMX and (virtual) COM port on PC.
https://www.ghielectronics.com/catalog/product/287

Of course: Every module is open source and you can build a similar thing on your own.


#6

thank you,
but this is the output (-5V, 5V) is output is TTL or RS232
I look in the NET I find that the TTL is (0-3.8v or v)


#7

if you have emx devsys https://www.ghielectronics.com/catalog/product/129 then it has an rs232. so just use an rs232 cable. +/- 5v is an rs232 level not ttl


#8

thank you
but my PC have voltage (-12, +12)
is that I can connect directly with EMX Development System or there is a circuit to convert the signals to (+12,-12V) to (5, 5v)


#9

its an rs232 signal, it is within rs232 spec.


#10

its an rs232 signal, it is within rs232 spec.
sorry I did not understand
SPEC: what this is:…?


#11

spec=specification

it is an rs232 signal coming from the PC, and its an rs232 signal coming from the EMX DevSys. The Devsys has the necessary TTL to RS232 conversion. Just plug an rs232 cable between them and youre done.


#12

thank you very much for your help @ Brett
my greetings