MIKROE-2152 Datasheet MIKROE-2152 | P1-P3

2x2 Key click

IC/Module

SN74HC14 datasheet

[1]

74HC32 datasheet

[2]

Interface AN, RST, CS, PWM, INT

Power supply 3.3V or 5V

Product page

2x2 Key click

[3]

Schematic

2x2 Key click schematic

[4]

2x2 Key click has a 4 PCB button keypad. It carries the SN74HC14 Hex Schmitt-Trigger Inverter from Texas

Instruments and 74HC32 quad 2-input OR gate from NXP. The click allows multiple key presses and is designed to

use either 3.3V or 5V power supply.

The silkscreen markings on the click let you know which button is which. The buttons that can be independently

read.

Features and usage notes

The debounce circuit

In electronics, two metal components tend to bounce or create multiple signals when they are in contact with each

other, like when you push a button before they get to a stable state. You want a single contact to be recorded, but the

microcontroller records this as if you pressed the button many times.

So debouncing is, as the name states, the removal of bounces or spikes of low and high voltages. Graphically

speaking, you want a clean line, not spikes. A debounce circuit makes sure that there are no voltage changes on the

output.

2x2 Key click

Interrupt service routine

All four Schmitt-trigger outputs are connected to input pins of the logic OR gate 74HC32, whose output is directly

connected to the INT pin on mikroBUS. This pin is used to signalize an interrupt to the MCU any time a button is

pressed.

In this way, the MCU software can be implemented as a simple polling routine, without any delays programmed in

the code, like it would be necessary if there wasn’t a hardware debouncing circuit present.

Thanks to the INT pin you can easily program a common interrupt service routine, in order to detect when a button is

pressed (the state of the button changes from low to high logic level).

Key features

•• 74HC32 quad 2-input OR gate

•• High noise immunity

•• Low power dissipation

•• SN74HC14 Hex Schmitt-Trigger Inverter

•• Outputs Can Drive Up to 10 LSTTL Loads

•• Low Power Consumption, 20-μA Max ICC

•• 4 black PCB buttons onboard

•• Interface: PWM, INT, AN, RST, CS pins

•• Runs on either 3.3V or 5V power supply

Additional information

•• J2 is the interrupt enable pin (by default it is in the enable status).

•• J1 is the power selection pin.

Pinout diagram

This table shows how the pinout on 2x2 Key click corresponds to the pinout on the mikroBUS™ socket (the latter

shown in the two middle columns).

Notes Pin

mikroBUS

Pin Notes

When button T1 is pressed the pin is

active

T1-OUT 1 AN X PWM 16 T4-OUT When button T4 is pressed the pin is active

When button T2 is pressed the pin is

active

T2-OUT 2 RST INT 15 TINT Interrupt pin that notifies the MCU that a button is

pressed

When button T3 is pressed the pin is

active

T3-OUT 3 CS TX 14 NC

NC 4 SCK RX 13 NC

NC 5 MISO SCL 12 NC

NC 6 MOSI SDA 11 NC

Power supply +3.3V 7 +3.3V +5V 10 +5V Power supply

Ground GND 8 GND GND 9 GND Ground

2x2 Key click

Programming

The demo initialises the TFT display and sets pins to operate in input direction. The main fucntion of the demo uses

the polling method to check if inputs are on an active level. The TFT display shows the button state according to

detect level.

void main()

{

system_init();

Draw_Taster(X1, Y1, RELEASED, "T1");

Draw_Taster(X2, Y1, RELEASED, "T2");

Draw_Taster(X1, Y2, RELEASED, "T3");

Draw_Taster(X2, Y2, RELEASED, "T4");

while(1)

{

if(Taster_Pressed(TAST1, &t1_state))

Draw_Taster(X1, Y1, PRESSED, "T1");

if(Taster_Released(TAST1, &t1_state))

Draw_Taster(X1, Y1, RELEASED, "T1");

if(Taster_Pressed(TAST2, &t2_state))

Draw_Taster(X2, Y1, PRESSED, "T2");

if(Taster_Released(TAST2, &t2_state))

Draw_Taster(X2, Y1, RELEASED, "T2");

if(Taster_Pressed(TAST3, &t3_state))

Draw_Taster(X1, Y2, PRESSED, "T3");

if(Taster_Released(TAST3, &t3_state))

Draw_Taster(X1, Y2, RELEASED, "T3");

if(Taster_Pressed(TAST4, &t4_state))

Draw_Taster(X2, Y2, PRESSED, "T4");

if(Taster_Released(TAST4, &t4_state))

Draw_Taster(X2, Y2, RELEASED, "T4");

t1_state = TAST1;

t2_state = TAST2;

t3_state = TAST3;

t4_state = TAST4;

Delay_ms(POLLING_PERIOD);

}

P1-P3 P4-P5

MIKROE-2152

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Manufacturer:

Mikroe

Description:

Daughter Cards & OEM Boards 2x2 Key click

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MIKROE-2152