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Topic: ONEWIRE to RS232 with arduino and some more features (Read 244 times) previous topic - next topic

sirwiz

My goal is to get code from onewire reader (DS1990A transmision emulation) do some modification and send it to RS232 port. When arduino will do modification i want also light up/down 2 leds and make sound from buzzer  in reader which are controled by connecting to ground.

I made schema as attached.



Can someone check my schema cos im not electronic ninja?

MAS3

Hi.

How are you powering this ?

I see some 2 pin 12 volt connector (J4), with both pins to 12 volt and none to GND.
These 12 volts go to your 6 pin connector J3 and nowhere else, is that what you meant to happen ?

The red and green LED are connected to J3's 12 volt via a resistor i must assume ?

What's the function of J1 ?

Transistor T1 will invert your serial communications, you need to take that in consideration.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

sirwiz

Thank you for response.

5V to VIN and 12V are from computer power supply (5 and 12 have common GND).

J1 is from old project, to make board more uniwersal for me,

RED/GREEN/BUZZ have own volatge regulator and rezistors inside redaer.



J4 to J3 is only for connect 12V from CPS to reader.


Ron_Blain

You my want to read up on RS232 with a focus on levels. RS232 does not use 5 volt TTL levels.

Ron

sirwiz

That why i use BC547 as level converter for TX. RS232 works from 3V to 15V, so 5V is OK, i test above solution and works better then cheap max232 (for TTL TX to RS232 RX) i dont need full tansmission, just send data from arduino direct to RS232 on main unit.

Paul_KD7HB

That why i use BC547 as level converter for TX. RS232 works from 3V to 15V, so 5V is OK, i test above solution and works better then cheap max232 (for TTL TX to RS232 RX) i dont need full tansmission, just send data from arduino direct to RS232 on main unit.
That is why Ron suggested you review RS-232. IT uses +-3 to +-25 volts, not just +3 to +15.

Paul

sirwiz

I do not "borrow" negative from TxD, but most of modern rs232 chips accept 0V as logic high and 5V as low. I test it with some rs232 cables and also build in rs232 port on computer. It works.
http://www.radanpro.com/Radan2400/PC/RS232C%20level%20Converter%20using%20Transistors.htm

Paul_KD7HB

I do not "borrow" negative from TxD, but most of modern rs232 chips accept 0V as logic high and 5V as low. I test it with some rs232 cables and also build in rs232 port on computer. It works.
http://www.radanpro.com/Radan2400/PC/RS232C%20level%20Converter%20using%20Transistors.htm
Obviously, you do not need more help.

Paul

raschemmel

#8
Jun 08, 2020, 03:41 am Last Edit: Jun 08, 2020, 04:00 am by raschemmel
Quote
Some people just can't stay on the road...
Point being: Don't mention a communication protocol that has been around longer than you have if you
are not going to respect the protocol. Either respect the protocol by following it or don't mention it.
If you are going to invent your own protocol , fine, but don't call it RS232 or expect us to consider it as
RS232 because as ANYONE who knows ANYTHING about RS232 can tell you, it is a bipolar voltage protocol.
You labeled one pin RS232_TX but you have only positive voltages in your circuit, so your label is WRONG.
You CANNOT label that pin RS232_TX if you have NO RS232 circuitry, regardless of your "it works " claims.
Either follow the protocol or don't discuss it. It's really that simple.

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