baud rate problem URGENT

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

Here is the example Arduino has:

void setup() {
  Serial.begin(9600);
}

void loop() {
  Serial.println("hello world");
}

Output for the code above is:

hello world
hello world
hello world
hello world
hello world
hello world
hello world
hello world
hello world.........(and so on)...........

If I change the "Serial.begin(9600)" to " Serial.begin(14400)", and choose the 14400 option in the serial monitor, then the output is:

h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù*ùè~Kt h¥êAïÁ*-!Ù ....... (and so on).....

Why is it printing junk?
I have an Arduino Nano ATmega328
mini-USB
Help! :cry:

2

Have you tried 19.2k?
Any other speeds?

3

There's someone here:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1287734947
witha very similar problem - maybe you shoulld get in contact.

4

Groove: Yes, I tried other combos as well uncluding 19.2k
AWOL: That other person is ME! :smiley:

5

Groove: Yes, I tried other combos as well uncluding 19.2k

Talk about a terse answers to the question. :wink:

Well don't hold us in suspence, what was the result of trying various other baud rates? Which speeds work and which speeds don't?

6

retro: All baud rates above 9600 produce the same " junk " values. :frowning:

7

retro: All baud rates above 9600 produce the same " junk " values.

OK, Which PC OS are you using and what version of the Arduino IDE software?

Edit PS:
The Arduino bootloader for your NANO uploads new sketches at 57600 baud, so the fact that you can upload new programs says it's not just the speeds that you are trying to use, but rather some software problem.

Lefty

8

AWOL: That other person is ME!

Really?
Why post the same question twice?

9

Are you running that actual sample code? In your other post, you say you are taking analog readings. Have you tried temproarily disconnecting the analog circuitry and just running the sample code with no other connections?

I don't think it has anything to do with the mini-USB connection. If you are setting 9600 baud in the code, the Arduino is actually using 9615.38 baud which is close enough (i.e., UBRR0 register = 103). At 14400, the UBRR0 register is 68 which gives an actual baud rate of 14492.75. That is also plenty close.

Have you tried it with HyperTerminal or some other terminal program instead of the serial monitor? Also, try 19200 instead of 14400 just for kicks. 19200 is a more commonly used baud rate anyway. Post the actual junk that comes out at 19200 in case someone wants to take the time and analyze it down to the bit level to determine what's really going on.

10

The problem was somehow fixed last night. I removed a resistor I had connected to one of the digital pins and to TX pin (I thought it was connected to ground, but I accidentally had it connected to TX). I still don't understand how this fixed the problem / why it caused the problem in the first place but thank you all for answering my questions! I am now communicating at 115200 baud rate!!!! ;D