At 20MHz, then yes. The internal clocks run at 128kHz, 1MHz, 8MHz, and 16MHz.
If you have already burned a bootloader/fuses for the crystal option, which it sounds like you might have, you will need to hook a crystal/resonator to the chip to change the programming or fuses.
Do you mean it is NOT possible to program a attiny 85 20 MHz without an external clock. or should it be possible to program it a 8 MHz using the internal clock?
So if it is possible what am I doing wrong?
Neither the burn boot loader or the sketch loading are working, so I wander if I can use these chips with the Arduino ISP . (note that I also did try without invoking the burn bootloader and upload a sketch directly selecting ATtiny internal 1MHz and 8 MHz)
I did the test with several ones without any success and I am sure about the pins connections with the Arduino.
So please confirm that a 20 MHz version will or will not work with the Arduino ISP (or that an external 20 MHz clock is necessary).
Thanks to confirm that it should work .
Regarding the arduino reset pin, a capacitor to the ground or a resistor to +5v doesn't help.
I will try with an older version of arduino running on window in stead of Mac .
But I don't see the kind of mistake I am doing.
Robert
I actually did something similar just now, exact same part number. I'd only just received the chips and wanted to make sure my setup would work. I used the Uno R3 as the ISP, and managed to hook everything up, run the "burn bootloader" operation (I set it to 8mhz, BOD disabled, as there's no way I need a clock freq. of 20MHz), and got a simple program up and running which blinked a bicolour LED and peeped a piezo buzzer.
I followed the instructions here: http://hlt.media.mit.edu/?p=1229 including using the 10uF cap between reset and ground on the Uno. I'm not sure exactly what you might be doing wrong but the setup ought to work!
I was confused with the explanation of http://hlt.media.mit.edu/?p=1695 using the bootloader stuff (still unclear for me and I will try this later), and I have missed some details not obvious for me like:
Loading de Arduino ISP selecting as board Arduino UNO, this WITHOUT the RESET capacitor/resistor, then
ADD the capacitor/resistor and then load the wanted sketch after selecting the Attiny85 1MHZ as board.
Practically the sequence is the following:
Connect the Arduino UNO with the serial interface via the USB cable (ATtiny already connected as describe by the URL above) but without 10uF capacitor between GND and RESET
Ensure that the board selected is the one for the Arduino (my case Arduino UNO) menu Tool>Board>Arduino UNO
Upload the Arduino ISP sketch from the menu File>Examples>ArduinoISP
Add the capacitor between GND and RESET
Select the ATtiny model with the default clock 1MHz (my case Tool>Board>Attiny85 (internal 1MHz clock))
Select one sketch to upload (e.g. File>Examples>01.Basic>Blink)
Change the settings according to the pins of the ATtiny (e.g Pin 13 becomes Pin 0>
Upload the sketch (rmk: File>Upload or File>Upload using programmer, makes no difference)
An in this case a LED connected to pin 0 of the Attiny should blink.
Pins 9, 8, and 7 on the Arduino provide status for ArduinoISP when it's running. Notably, pin 9 provides a heartbeat to show that ArduinoISP is loaded on your Arduino; that would have eliminated your primary mistake. I highly recommend it to help maintain your sanity in the future
First of all thank you darvade. I have been going round and round all day with this issue. I then came across you post and bingo it works.
I do how ever have a question for all you pros.
In the updatded post from Hi Low tech is states this.
"By default, the ATtiny’s run at 1 MHz (the setting used by the unmodified “ATtiny45?, etc. board menu items). You need to do an extra step to configure the microcontroller to run at 8 MHz – necessary for use of the SoftwareSerial library. Once you have the microcontroller connected, select the appropriate item from the Boards menu (e.g. “ATtiny45 (8 MHz)”). Then, run the “Burn Bootloader” command from the Tools menu. This configures the fuse bits of the microcontroller so it runs at 8 MHz. Note that the fuse bits keep their value until you explicitly change them, so you’ll only need to do this step once for each microcontroller. (Note this doesn’t actually burn a bootloader onto the board; you’ll still need to upload new programs using an external programmer.)"
I could never get it to work. can anyone tell me what its all about.
avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny85
avrdude: Yikes! Invalid device signature.
Double check connections and try again, or use -F to override
this check.