arduinoledpins
In my project I need to use
7x tact switches
6x LEDs
3x 7 led segments
1 arduino uno board
my prof says we can use any ICs
but arduino uno's pins cannot accomodate all those needed values.
I need to manipulate all the tact switches and the 6 LEDs so the only thing that can be reduced is the issue with 7 led segment.
Can you suggest a way that I can reduce the number of pins needed to be used in arduino uno?
You could use a 74HC595 shift register and this circuit, courtesy of Roman Black.
That will buy you 8 outputs with a single 25-cent chip.
8 parallel strands of 2 LEDs each and a 150ohm resistor. All loose anodes should be connected to V+. The loose cathodes should be connected to the collector of a TIP31 NPN transistor. The emitter should be connected to ground. The base should be connected to a 100ohm resistor, and the other side of the resistor should be connected to a digital output. 16 LEDs, 9 resistors, 1 transistor, 1 digital output.
(12V−(3.2V⋅2+1.2V))/30mA = 146.66667 Ω
30mA⋅8 = 240 mA
(5V−1.8V)/(30mA⋅8/10) = 133.33333 Ω
simulate this circuit – Schematic created using CircuitLab
Best Answer
For 7 switches , MM74HC164M SHIFT REG 8BIT PISO 14-SOIC
For 6 LEDs and 2 LED digits , (3) SIPO's MM74HCT164MX SHIFT REG 8BIT 14SOIC
For (3) LED digits choose LEDs with BCD to 7seg decoder integrated.
The clk & data lines are shared but a chip selector is needed,.