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Author Topic: Arduino board DB9 socket  (Read 830 times)
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I want my homemade arduino to communicate with my PC. Do I need a max32 chip in this diagram??? Isn't there the chip missing for the RS232 communication..?
http://arduino.cc/en/Main/ArduinoBoardSerialSingleSided3
http://arduino.cc/en/uploads/Main/ArduinoSeverinoSchematic.png

Kindly explain how to connect this board to my pc..? Without the RS232 how is that possible in the diagram.? I am a bit confused.
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This arduino schematic has RS232 (max32) chip in the circuit

http://www.vintagecomputercables.com/img/freeduino_serial_v2_schematics_L.jpg

but the above schematic (1st post) dont have the RS232 chip, so its a bit confusing. kindly assist.

thanks.
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Current Arduinos do not have any RS-232 serial, they communicate to the PC using USB.

On the PC end it looks like a virtual serial port.

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yes I know that sir, but actually I have max232 chips & DB9 socket pair in my inventory. So I want to make some useful things out of it.
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Your question was

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I want my homemade arduino to communicate with my PC. Do I need a max32 chip in this diagram?

The answer is no, you don't need a MAX232 chip, these days you would use an FTDI232 chip and talk using USB.

Quote
I have max232 chips & DB9 socket pair in my inventory. So I want to make some useful things out of it.
Now you are saying that you have these components and want to find a use for them, that's a different issue.

Yes you could connect them to an Arduino and talk to a PC, but do you actually have a computer with an RS-232 port?  They are few and far between these days.

If you don't and you really want to use the chip then you will have to find something that talks RS-232 and connect to that.

So what is the end goal, to talk to a PC, to use RS-232 with anything, or to talk to a PC using RS-232?

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You are ri8 sir, my laptop doesn't have DB9 connector. I forgot to mention 1 thing. I already have a bafo converter, so serial to usb is no an issue. I just want my homemade arduino board to talk to my laptop for uploading sketches using DB9 / RS232 protocol like the previous versions of arduino boards.

Ftdi chips are costlier & need more mastery in soldering as they are smd components. Thats why I want to avoid them. Max232 are cheaper, easy to solder, I have them in my inventory. Want to make it by myself.
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I already have a bafo converter, so serial to usb is no an issue.

So what is a bafo converter, got a link?

A common solution for people building their own boards but not wanting to use SMD chips is to use an external USB serial converter. There are many inexpensive Asian offerings on E-bay.

http://www.ebay.com/itm/New-USB-2-0-to-TTL-UART-6PIN-Module-Serial-Converter-CP2102-STC-PRGMR-Free-cable-/251159428933?pt=LH_DefaultDomain_0&hash=item3a7a44bf45

Lefty
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http://www.ebay.in/itm/USB-to-Serial-Cable-Convertor-USB-to-9-Pin-Cable-/160983558492?pt=LH_DefaultDomain_203&hash=item257b5e295c

This ia a bafo converter.

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some usb serial breakout boards have RST, some have RTS, some have DTS pinout along with Tx, Rx, Vcc, GND... Which one should I buy..?
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some usb serial breakout boards have RST, some have RTS, some have DTS pinout along with Tx, Rx, Vcc, GND... Which one should I buy..?

The arduino IDE using avrdude to upload generates a pulse on both DTR and RTS signals to trigger the on-board auto-reset function, so any USB TTL serial converter that makes either the DTR or the RTS signal available will work.

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The single sided serIal board you link to has its own transistor based rs232level converter, expects "real" rs232 voltages on the db9 port, and should not need an additional max232 converter.

Whether your bafo converter actually provides a suitable rs232 level is a separate question...
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