I will describe my problem as best I can, starting with the ATtiny85. Apologies if it is a bit long, Programming is via Arduino IDE (version 1.8.7) together with DrAzzy’s ATtiny core.
Program is a version of the original DCC++ base station adapted to run on the 85. All code apart from that associated with Mobile Decoder control is stripped to make it fit in the 8Kb of flash memory. I use a second ATtiny85 as controller. Communication between the two is via I2C. The system works great and I am running my small layout using it. (Original discussion is here.)
I now started experimenting with a new version to control Accessory Decoders - need to control those turnouts (this time stripping the mobile decoder code). I started by just loading my original mobile version onto an ATtiny85. Uploading is done using Arduino ISP with an UNO. Upload worked fine and the DCC signal LED light as expected. To verify I am looking at the correct LED, and shows what it is assumed to show, I added the normal diagnostic code to slow the DCC signal down to about 2.5Hz. Diagnostic is normally enabled via an instruction from the controller. Since that is not connected yet, I added it to the end of the Setup() function. Sketch uploaded fine and the LED slowed down to the expected approximate 2.5Hz.
When the processor is slowed down (by 256x), all communications obviously cease and it is necessary to either reset or recycle the power. Restarting, however, runs the same slowed down version so I need to upload the code again with the slowdown removed. This is where the problem started. The ISP programmer now gives an “Invalid device signature” error. I substituted the 85 with a different one and the upload works fine (confirming there is no connection problems). Replace the problem 85 and the error is back (the code is still running pulsing the LED).
Setup is very minimal. ATtiny85 on breadboard with 5V and 0.1uf cap to pin 8, ground to pin 4 and ISP to respective pins. LEDs with resistors to pins 1 and 3.
I initially started with an ATtiny84 (with adapted code), followed the same procedure as above and had the same resulting error message. I thought my little home-made breakout board might have gone faulty, hence the switch to the 85.
Attached the verbose output from the aborted IDE upload.
I would appreciate any ideas to get the upload working again.
ErrorMessage.txt (3.82 KB)