[SOLVED] Having issue with ATtiny85 @ 8MHz

Other Hardware 3rd Party Boards
1

I am attempting to get my sketch to run on an ATtiny85, using the core from Google Code Archive - Long-term storage for Google Code Project Hosting. and the board configuration for ATtiny85 @ 8MHz (internal oscillator).

Here are the steps are am attempting

  1. Select board, ATtiny85 @ 8MHz (Internal oscillator, NO BOD)
  2. Uploaded bootloader
  3. Upload this sketch
#include <Entropy.h>

void setup()
{
  Serial.begin(38400);
  Entropy.Initialize();
}

void loop()
{
  Serial.println(Entropy.random());
}
  1. Monitor the output of pin7 with a serial program (minicom) and an oscilliscope

With the above steps I received no data on the serial terminal, nor does the oscilliscope see any signals (see image capture attached). When I use the same circuit, sketch, and core with the ATtiny85 @ 16MHz (Internal PLL, etc...) board configuration, I receive the expected data on the serial terminal and see the signal on the oscilliscope (see attached image capture). Originally we thought it might be not receiving data on the serial terminal due to the error associated with the internal clock at a frequency different from what it was calibrated on, but the lack of signal on the oscilliscope would indicate that something else is going on. Any suggestions?

85_8mhz.bmp (146 KB)

85_16mhz.bmp (146 KB)

2

At the time I wrote Tiny Debug Serial, I did not know about the ability to run the processor at 16 MHz using the internal oscillator.

So, I assumed if the clock speed was 16 MHz, a crystal or resonator must be connected to the XTAL pins and the serial output pin is moved to the other side of the processor (pin 7; PB2). The normal serial output pin for the ATtiny85 is pin 2; PB3.

In case you're especially curious, the code of interest is here...
http://code.google.com/p/arduino-tiny/source/browse/trunk/hardware/tiny/cores/tiny/TinyDebugSerial.h#607

3

Thanks! That worked perfectly!