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Topic: The arduino mega serial communication (Read 2207 times) previous topic - next topic

new99

To the communication serial of the arduino mega, I have that connect a max232 or the arduino already it has?

Do pins which connect the max232 db15 connector?

Many thanks for your help

(google translate)

sterretje

The serial ports an the Mega are TTL level, not RS232

Mega schematic; found via the Mega product page

If you understand an example, use it.
If you don't understand an example, don't use it.

Electronics engineer by trade, software engineer by profession. Trying to get back into electronics after 15 years absence.

new99

The serial ports an the Mega are TTL level, not RS232

Mega schematic; found via the Mega product page


That mean that I can connect them pin tx, rx  without need of a max232?

Many thanks for your response. Good day / night.

new99

I need to send data by the RS232 port, through the pines RX1... n, TX1... n; can I do it directly without using the MAX232?

Budvar10

Arduino - serial converter (MAX232) - computer RS232.
Arduino has TTL signal level. It cannot be connected directly to the computer. You will need level converter based on MAX232 or similar.
Arduino clone with ATmega1284P   http://forum.arduino.cc/index.php?topic=277260.0

new99

Hello, I want to transfer data from the Arduino to the computer.

But before I want to say, that my arduino mega, will be constantly fed with 7v.

My question is that if to send data, can I use a connector (USB-to-DB9 CONNECTOR) as shown in the image (this is to avoid using a max232 in the ports of the arduino)?

my other question is that if I use the USB-to-DB9 connector, I don't get any extra power that harms my arduino. This is because to my arduino is powered with a supply voltage of 7v.

(translate.google)

CrossRoads

DB9 also has a Ground connection, on pin 5. Power is usually not supplied on any pin.
If you connect the DBP and leave the power supply off, the Arduino should not have power. Try it.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Southpark

Hello, I want to transfer data from the Arduino to the computer.
So, you don't want to just transfer data from arduino to computer using direct USB connection between computer and arduino, right?

Do you specifically want to use RS232 as the middle guy?

new99

So, you don't want to just transfer data from arduino to computer using direct USB connection between computer and arduino, right?

Do you specifically want to use RS232 as the middle guy?
Not necessarily, I just want to transfer data from the arduino to the computer. The problem of making them from arduino USB to computer USB is that the computer supplies power to arduino.

And my arduino will be connected to a 7v volt source.

new99

DB9 also has a Ground connection, on pin 5. Power is usually not supplied on any pin.
If you connect the DBP and leave the power supply off, the Arduino should not have power. Try it.
Hi, I need to send arduino data to the computer. Normally connected the arduino and the computer through USB works correctly but the problem is that through USB the computer supplies arduino electrical power.

My arduino is powered apart by a 7v voltage source.

How do I send data from the arduino to the computer without the computer supplying electrical power?

Please help, I'm new.

larryd

The Arduino has a built in power switch.
Your 7 volt to the power jack takes precedent over the USB 5v from the USB cable.



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Wawa

The Arduino has a built in power switch.
Your 7 volt to the power jack takes precedent over the USB 5v from the USB cable.
7volt on the DC socket is not enough to switch off USB power.

7.5volt (7.3) or more is needed for that.
Leo..

larryd

Maybe the OP is using Vin.
Maybe they are not measuring the voltage to the decimal.


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If you are asked a question, please respond with an answer.
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Wawa

Maybe the OP is using Vin.
Maybe they are not measuring the voltage to the decimal.
7volt on V-in would be above the switchpoint (2 * the 3.3volt pin), but the picture shows the DC socket as entry point.
Leo..

larryd

Perhaps the OP has some adjustment on that power supply potentiometer seen in the image I missed.


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