Based on this quite good description I’ve made a circuit to program Attiny85.
In this way, it is reposted with rather little additional value, but perhaps in a more understandable way.
It will be fun!
Required parts:
- Arduino Nano
- Attiny85
- 10 uF electrolytic capacitor
- LED
ISP (In-system Programming) mode
Put the Arduino Nano in ISP mode. Fortunately, you can find an example of this in the Arduino IDE: File -> Examples -> ArduinoISP - upload without modification.
Add Attiny85 support to Arduino IDE
Under File -> Preferences -> Additional Boards Manager URLs, enter the following: https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json. (mirror)
(If you find the URL unusable in the meantime, check out David A. Mellis’ Github.)
Under Tools -> Board -> Boards manager choose “attiny” (by David A. Mellis) and install it.
If all goes well, you will see “Attiny” under Tools->Board.
Connecting Attiny85 with Arduino
Check Attiny85 pinout:
(source)
Arduino Nano - Attiny85 connection:
- 5V - VCC
- GND - GND
- D13 - PB2
- D12 - PB1
- D11 - PB0
- D10 - PB5 (RESET)
- RST - 10 uF C - GND*
*The original description incorrectly states that the anode (+) of the electrolytic capacitor should be connected to GND, of course the cathode should be connected to GND.
Prepare uploading Attiny85
In Arduino IDE select the following options:
- Tools -> Board: Attiny25/45/85
- Tools -> Processor: Attiny85
- Tools -> Clock: Internal 8MHz
- Tools -> Programmer: Arduino as ISP*
*Note that we usually use AVRISP mkii for Arduino…
By default Attiny85 runs at 1MHz, so you need to Tools -> Burn Bootloader.
Test it!
If everything went well so far, open the blink example (File -> Examples -> Basics -> Blink). Change the pin from 13 to 0. (Or from LED_BUILTIN to 0.) Upload.
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin LED\_BUILTIN as an output.
pinMode(0, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(0, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(0, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
Now, this is harder to test than an usual Arduino app, because you need a separate power source to drive the Attiny. In the original descripton, a 3V button cell is used. But you can also draw the required current from the Arduino (disconnect the original wiring, of course):
- PB0 - LED - GND
- 3.3V - VCC
- GND - GND
Profit!
Errors
Under Arduino IDE 2.x you may get “A programmer is required to upload” error. Use Sketch -> Upload Using Programmer when uploading to your ATtiny85. (ref)
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