Uploading "blink" to external ATMEGA386P-AU with Arduino Uno R3 (beginner, getting started help)

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Hardware changes made! Added 10 uF on UNO Reset to Ground (tantalum), added 47K on target RESET to +5V, added 22 pF to ground 2 places on target pin 7/8 (at crystal.)

Here's an updated diagram of the test set-up:

help-diagram-1r1
help-diagram-1r1960×720 56.5 KB

The capacitor on the Arduino board was installed after I re up-loaded the ArduinoISP application to the board, so my understanding is that the capacitor (RESET to GROUND, 10 uF) will inhibit further changes to the ATMEGA328P-PU DIP package part on the Uno.

To avoid confusion with the flash repetition rate that seems to be in the bootloader (appears to have been 10 Hz, which is by coincidence what I had initially set Blink2 to); I changed blink2 to 4 Hz rate (from 10 Hz.)

Now (with the Uno still ostensibly set as ArduinoISP and the 10 uF capacitor in place between RESET and GROUND on the Uno, I used AVRDUDESS to upload the (modified to 4Hz) version of BLINK to the target device.

After upload completed, the LED on the Uno was flashing at 4 Hz rate, the target's RESET pin (29) is indeed pulled up to +5V, and the intended output PD7 on the SMD part (pin 11) remains at 0V output or floating (can't tell which at this point.)

So, assuming that the capacitor installed on the Uno prevents the CPU there from intercepting any subsequent firmware upload, here's the behavior after uploading the modified Blink:

  1. No target attached, power-up Uno via USB. LED blinks 3 times rapidly, then is on steadily. AVRDUDESS "detect" function reports ERROR: Unknown signature 000000.

  2. Target attached, power-up Uno via USB. LED blinks 3 times rapidly, then starts blinking at 4 Hz rate, continuously. AVRDUDESS "detect" function reports Detected 1e950f = ATmega328P. Pin 11 of target device (PD7) is not generating output voltage pulses as expected.

Given that the Uno's CPU is evidently executing BLINK2 (the 4 Hz version), I do not see how the application ended up there rather than in the target device. I also do not see how AVRDUDESS is still able to treat the Uno as "Atmel AVR ISP" if it's running Blink2 (unless both programs can run concurrently??)

I tried both hex files from the build of Blink2 (with and without bootloader); the result is the same in both cases (the Uno's LED flashes at 4 Hz after it starts up, and Pin 11 of the target remains inactive.

That's as far as I can get at this point - would appreciate another look over my shoulder for sure!

Dave