baud rate set to 9600 but monitor works only if set to 4800

Recently inherited a friend's "junk box". Found an unused AT-Mini board from Mikroelectronika, decided to give it a try. Seemed to flash in the Arudino IDE as a Due 328 board.

Turning a pair of pumps on and off works fine. Also Measuring temperature of fluid flow with an LM35 sensor, baud = 9600 and using the Arduino IDE to monitor ... strange problem

PROBLEM: the monitor must be set to 4800 else jiberish is printed. I tried this sketch on a Due and it printed to the monitor at 9600 baud so it must be something to do with the AT-Mini board. Thought I'd try here for understanding before swapping out to the Due.

FYI, control is via transistor switching of low current pump motors following http://www.instructables.com/id/Use-Arduino-with-TIP120-transistor-to-control-moto/.

I think the AT-mini clock is 8MHz so the serial port speed must be set to twice the desired speed. The sketch you are using sets the baud rate to 9600 which works as 9600 on 328-based boards (and on the Due) but results in 4800 on the AT-mini.

Pete

Most likely the CPU frequency for the board type that you have selected is not the actual clock frequency of your Arduino.

Check you have selected the correct board type. If you have, look up the clock frequency defined for that entry and compare it with the frequency you think your Arduino runs at. If it's different then correct the board entry, or create a copy with the correct frequency. If it's the same then perhaps you're mistaken about what the actual frequency is, so you need to resolve that.

Procyan: PROBLEM: the monitor must be set to 4800 else jiberish is printed. I tried this sketch on a Due and it printed to the monitor at 9600 baud so it must be something to do with the AT-Mini board. Thought I'd try here for understanding before swapping out to the Due.

Right from their website:

It comes in two versions: 5V and 3.3V. 5V version features 16MHz SMD crystal oscillator while 3.3V version contains 8MHz oscillator.

Is yours a 3.3V version? If so, it's got an 8 MHz oscillator.