Qwiic Keypad Hookup Guide

Contributors: QCPete, santaimpersonator

Arduino Library

The easiest way to install the Arduino library is by searching SparkFun Qwiic Keypad inside the Arduino library manager. To manually install, head on over to the GitHub repository or feel free to download the library here!

Library Functions

The Arduino library is commented and the functions should be self-explanatory. However, below is a detailed list of the available library functions.

.begin() or .begin(Wire, deviceAddress)
Creates a connection to an I²C device over the I²C bus using the default or specified I²C address.

.isConnected()
Tries to connect to the device at the I²C address stored in the library.

.getVersion()
Returns a string of the firmware version number.

.setI2CAddress(newAddress)
Changes the I²C address to newAddress. Once changed, the new I²C address is saved in the EEPROM of the Qwiic Keypad. Reconnects to device using new I²C address. (The new address is printed out in the Serial Monitor.)

.getButton()
Returns the button at the top of the stack (aka the oldest button). In order to read this register for the first time, the FIFO needs to be incremented with the .updateFIFO() function first.

.getTimeSincePressed()
This function reads the register that holds the time since the button (at the top of the FIFO stack) was pressed. In the firmware, the ATtiny85 actually responds to a request event (register read) and calculates the time since the button was pressed at that moment and updated the register. Like the .getButton() function, in order to use this function for the first time, the FIFO needs to be incremented with the .updateFIFO() function first.

.updateFIFO()
Used to increment the FIFO stack- In the library, this function sets the updateFIFO register to 0x01. Once there is a request event (i.e .getButton() or .getTimeSincePressed()), the FIFO is incremented and the firmware clears the updateFIFO register back to 0x00.

Examples

There are six examples in the Qwiic Keypad Arduino Library to get you started with using Qwiic Keypad. These example files are named with self-explanatory titles, but in case you want more information, see the descriptions below.

• Example1_ReadButton

  This example connects to the Qwiic Keypad using the default I²C address saved in the library. The sketch loops through reading the register for the button at the top of the FIFO stack and incrementing the FIFO. The example then prints out the value over the Serial Monitor. The * is represented by a space and the # is represented with a new line (or carriage return).

• Example2_ReadWithTime

  This example operates exactly like the Example1_ReadButton, except the time since the button was pressed is outputted with the button that was pressed in the Serial Monitor. With a ~1 second delay between checks for button presses.

• Example3_ChangeI2CAddress

  Caution: Will not work if I²C address jumper is bridged.

  This example connects to the Qwiic Keypad using the default I²C address set in the library and then prints out the I²C address and firmware version over the Serial Monitor. The sketch then, takes an input from the Serial Monitor to change the I²C address using a decimal value (DEC). Once the I²C address is changed, it is stored in the EEPROM of the Qwiic Keypad. After, the sketch connects to the keypad using the new I²C address and reads the registers for the firmware version again. The example then prints out those values over the Serial Monitor again.

• Example4_I2CScanner

  This example is from the I²C scanner example from the Arduino Playground webpage. The sketch scans for devices on the I²C bus and reports them on the Serial Monitor. This is useful for users who have forgotten the changed I²C address of their boards.

• Example5_InterruptRead

  Note: This example is requires soldering. A wire must be soldered to the INT pin and connected to an interrupt pin on your microcontroller. As written, the example assumes you are using a Arduino UNO based board, like our RedBoard. The sketch designates Pin 2 as the interrupt pin.

  This example operates exactly like the Example1_ReadButton, except that instead of constantly polling the keypad for button presses in the main loop, it responds to the interrupt (INT) pin. Utilizing an interrupt allows the MCU to execute a specific set of instructions (i.e. button read), outside of the main loop. For more details on interrupts, check out this tutorial on Processor Interrupts with Arduino .

• Example6_Keycode

  This example is a use case example, in which the user must input the correct key code: 1, 2, 3, 4. The sketch also implements a timeout, so that the user must input the correct code within 30 seconds.