1284P MightyCore 2x timing issue - 9600 baud rate transfers at 19200

Hi guys,

I’m having a great time with the 1284P. I’m not sure what I’ve done but it appears the timing is off by a factor of 2. I first noticed that delay(1000) took 500ms, and then I realized that if I set Serial to 9600, I’d have to select 19200 (9600 x 2) to read the transmission in the serial monitor. I made as simple sketch:

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

void loop() {
Serial.println("TEST");
delay(1000);
}

Can’t get any simpler than that. I’m using a 16MHz external osc, which must be right because on a hunch I tried to write the program after selecting 8MHz internal it wouldn’t sync. So the chip is indeed running at 16MHz.

This is with Mightycore 1.0.2 and Arduino 1.6.7. I’m quite confused because I have another 1284P based project at work that doesn’t have this problem. I would have been using Optiboot and an older version of Arduino though…

With the new board manager, if I do Arduino as ISP then select the Mightcore bootloader, it automatically downloads the bootloader to be burned right? I don’t need to replace some default one on my drive somewhere?

Should be explained here: http://forum.arduino.cc/index.php?topic=379427.15 :slight_smile: :