Serial library... can select with or without RS-232 transceiver?

Development Libraries
1

Is some way to implement a serial port at Arduino without use a RS232 transceiver chip or transistors?

At Serial library I din't see nothing about select this issue, I see only at a soft-serial library.

Best Regards
Frank

2

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3

Yes, you can have 0 to 5V level serial connection to other boards.
Either use D0/D1 & Serial.begin() and NOT connect the USB connector (or use it for +5/Gnd only, like with a wall charger), or use one of the software serial libraries with 2 other pins.

4

Hi all!
I'm talking about invert or not the serial levels from the at the Arduino's USART. All the RS-232 transceivers always invert the signal level so the first way to get out the transceiver is always a couple of transistor of a HEX inverter (74hc04).

What i want to know if I can connect to a RS-232 port without any of these inverter buffers. Generally when you do this trick only use two resistors, 100E for TX and 10K for RX. But you must set the level invert that TTL.

Best Regards
Frank

5

If you are going Arduino to Arduino, no inversion is needed.
D0 to D1, D1 to D0, Gnd to Gnd. +5 to +5 if not separately powered.

6

No no that is the issue.... connect the D0-D1 two resistors directly to any RS-232 port.
To do not use inverters or transceivers... Set inverted at the arduino

Best Regards
Frank

7

That is not good - RS232 has up to +/-15V levels. You can't take arduino pins past -0.5V to VCC +0.5V or you blow the protection diodes and pins.
If you want to connect to RS232, use a MAX232 or MAX3232 chip:
Examples:

(one works with 0.1uF caps, the other with 1.0uF).

8

FrankRadio:
No no that is the issue.... connect the D0-D1 two resistors directly to any RS-232 port.
To do not use inverters or transceivers... Set inverted at the arduino

There is no option in the Arduino's processor to invert the output of the UART, or indeed invert the input to it.

You could hack the software serial library if you want. However, the sort of circuits you are talking about only work on computers with piss poor RS232 implementations.