Damage caused to arduino uno.

Projects Networking, Protocols, and Devices
1

I had connected my arduino uno directly to my gsm modem(simcomm gsm 900) using the rx and tx pins(cross wired connection).Later i came to know that i had to use a max232 chip to interface the arduino with my gsm modem.I did upload a code to send and receive a message.I sent a message too from my mobile phone.I2C protocol has +12v and-12v but TTL has 5v and 0v logic levels.Has this damaged my serial port(rx and tx pins)?Please help.

2

Has this damaged my serial port(rx and tx pins)?

Can you still upload code to the Arduino?

3

Yes,i can still upload the code to the arduino.