- Generally speaking, yes. It's safe to try because a higher resistance results in a lower current in the circuit (Ohm's law) and 330Ω is relatively close to the desired 200Ω resistor.
- The higher resistance has resulted in less current to the point that there is not enough current for the circuit to operate reliably.
- The amount of power to be dissipated by the resistor exceeds the resistor's power rating. In addition to using Ohm's law to determine a resistor value, you also need to calculate the expected power dissipation of the resistor and ensure that the resistor's power rating (in watts) exceeds your calculated value.
- 1 (one). An input GPIO pin connected to +3.3 volts is a logical high.
- GPIO 21 is floating. It's not pulled up to +3.3 volts by a physical resistor or via code using a function call such as pi.set_pull_up_down(21, pigpio.PUD_UP).
- You must use a logic level converter. This could be a simple resistor-based...