4. (10 pts.) Interface an external switch to Port A pin 0 which operates using negative logic by using the required elements in the following schematic. Assume the design requires the TM4C microcontroller to limit the current flow into it to 1 mA (this is the maximum current that can flow along a path connected to the PA0). The TM4C microcontroller input low Viu ranges between (0V,1.155V) and input high VH ranges between (2.145V,3.3V). Another design constraint is that intenal pull up/down circuits will not be used. The 7406 driver's Volmax is 0.5V. Calculate an appropriate value for R. Show that voltages being applied to the PAO are within range for both logic levels for a negative logic switch interface. Draw the circuit by connecting needed elements, the ground and the power supply. You must show formulas, derivations and calculations to claim any credit. +3.3V +5V Microcontroller PAO 7406 4. (10 pts.) Interface an external switch to Port A pin 0 which operates using negative logic by using the required elements in the following schematic. Assume the design requires the TM4C microcontroller to limit the current flow into it to 1 mA (this is the maximum current that can flow along a path connected to the PA0). The TM4C microcontroller input low Viu ranges between (0V,1.155V) and input high VH ranges between (2.145V,3.3V). Another design constraint is that intenal pull up/down circuits will not be used. The 7406 driver's Volmax is 0.5V. Calculate an appropriate value for R. Show that voltages being applied to the PAO are within range for both logic levels for a negative logic switch interface. Draw the circuit by connecting needed elements, the ground and the power supply. You must show formulas, derivations and calculations to claim any credit. +3.3V +5V Microcontroller PAO 7406