Invalid Device Signature when using Arduino as ISP

Other Hardware 3rd Party Boards
1

Hi everyone – I’ve programmed for a while but I’m just getting into embedded programming and I’m following a book that uses avrdude with attiny85 but I keep getting a bad response when I try to setup my system.

Here’s the background on my system and what I’ve done so far:

  • Running windows 11
  • Installed avr-gcc and avrdude, both show correct versions when called from command line
  • Uploaded the Arduino ISP sketch to my Arduino Mega2560
  • Added 10uF cap from Arduino RESET to GND
  • ATTiny85 pin 1 → D10, pin 5 –> D11, pin 6 –> D12, pin 7 –> D13
  • D9 I’ve connected to a resistor and LED so that when the ISP program is running it slowly blinks

With that setup, I run the command:
avrdude -c arduino -p t85 -P COM3 -b 19200 -v

This is the output I get:
Avrdude version 8.0-20250112 (e3403b585)
Copyright see avrdude/AUTHORS at main · avrdudes/avrdude · GitHub

System wide configuration file is C:\tools\msys64\mingw64\etc\avrdude.conf

Using port : COM3
Using programmer : arduino
Setting baud rate : 19200
AVR part : ATtiny85
Programming modes : SPM, ISP, HVSP, debugWIRE
Programmer type : Arduino
Description : Arduino bootloader using STK500 v1 protocol
HW Version : 2
FW Version : 1.18
Topcard : Unknown

AVR device initialized and ready to accept instructions
Device signature = 00 00 00 (retrying)
Device signature = 00 00 00 (retrying)
Device signature = 00 00 00
Error: invalid device signature
Error: expected signature for ATtiny85 is 1E 93 0B. double check connections and try again, or use -F to carry on regardless

Avrdude done. Thank you.

I have verified that Arduino ISP sketch is 19200 baudrate
I have verified it is on COM3
The AT chip is new so I don’t see why it would be having clock issues
I also have two of the AT chips and tried both of them, so its not a chip failure
I have verified the wires are not loose
I have verified that AT is getting 5V

Any suggestions on what to try next?

Any help is appreciated. Please be kind – I’m new here.

2

Pins 10/11/12/13 are not the SPI pins on the Mega; check the Mega's schematic.

3

Thank you for your help. I’ve looked at the schematic and I’ve rewired it such that
AT pin 7 –> 52 (SCK), pin 5 → 51 (MOSI), pin 6 –> 50 (MISO). However, I was a bit confused about where AT pin 1 should go. I tried using D53 but that did not work however using D10 did work. Why is that? Thanks again for the help!

4

Pin 10 is used as used as the reset pin for the ATtiny and is coded in the ArduinoISP sketch

#define RESET 10  // Use pin 10 to reset the target rather than SS