Arduino <> Lobotomized Arduino <> Serial monitor

Hello friends.

I'm trying to talk with an Arduino through another unchipped arduino.

The code is:

void setup() { Serial.begin(9600); pinMode(2, INPUT); }

void loop() { Serial.println("send");

if (Serial.available()) {; delay(500); Serial.println("OK"); } delay(500); }

When I connect with de chipped arduino directly with usb I get "send" every 1/2 seconds and "OK" every time I send something. PERFECT If I connect using the unchipped arduino (gnd->gnd, vin->vin, tx->tx, rx->rx) I get "send" every 1/2 seconds and "OK" only some times. 1 every 20 times or less. It's... aleatory.

Any idea?


Hello friends.

Now I’m getting correct answer if I get Rx signal directly from pin 1 of FTDI.

PC <-> USB <->Arduino w/o atmega <-> ftdi pin 1 <-> Chipped board rx pin
                                     tx pin     <-> Chipped board tx pin
                                     5v         <-> 5v
                                     gnd        <->  gnd

Why is this happening?

Why is this happening?

Because you now have the hardware connected correctly.

mnnn... but if I use arduino pin 0 instead of use ftdi pin 1, I can't get correct transmission.

Why can't I use tx and rx pins directly?

PD: Now I'm using a transmission based on Messenger library.

The connection from the "Arduino pin 1" to the FTDI pin is through the chip that you removed.


FTDI txd goes to R8 first, atmega pin 2 and j1 pin 0 later.

Am I wrong?

In my test, I can get signal from one side of R8 (ftdi side) but not from the other side.

I have used different arduinos with same result.