I notice there is a 3 pulses/spikes on the UNO D11 (MOSI), D12 (MISO) and D13 (SCK) each time i press the reset button.
This is not observed in other IOs.
All above IOs are set as output.
D11 - 1.5V spike, 124ms between each
D12 - 3V spike, 124ms between each
D13 - 5V pulses, ~8Hz, 124ms pulse width (50% duty cycle).
Anyway to prevent this?
I used these pins at OUTPUT to trigger another circuits.
This caused false trigger when power up or reset.