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I'm running a simple program on an ATtiny26l but if i disconnect my AVRISP MK2 programmer it stops working completely. I'm supplying 5.4v to both VCC and AVCC pins (chcecked voltage).If i reconnect the avrisp it starts working again, and it also doesn't work if the programmer is not powered. Reseting the MCU or power doesn't help it simply refuses to work without an active programmer.

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    \$\begingroup\$ Schematic? Sounds like Reset needs pulled up. \$\endgroup\$
    – Matt Young
    Mar 30, 2016 at 20:41
  • \$\begingroup\$ Please provide additional info, have you checked your vcc when you have the programmer plugged in vs not? \$\endgroup\$
    – Voltage Spike
    Mar 30, 2016 at 20:51

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Solved! It seems that my power supply provides unreliable voltage or something. Adding a capacitor between vcc and ground solved everything.

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    \$\begingroup\$ It's called a "Decoupling Capacitor" and it is there to remove noise from the power supply rails that can otherwise upset the operation of the IC. You'll find them in every circuit that involves digital logic like MCUs. \$\endgroup\$ Mar 30, 2016 at 22:00

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