HC-SR04 and 1602

Simple ultrasonic sensor module HC-SR04 and 1602 LCD display were combined into useable digital yardstick.

Two versions of the sensor module from different suppliers worked similar way. The right one sometimes (name printed in the middle) had sometimes tendency to keep once entered “out of range” state forever. Simple transistor to switch on/off VCC did the trick – if the “out of range” state was longer than 1 second the module was switched off and switched on back.


The sensor is ooperated by standard Arduino commands, and  the display is controlled by the object from LiquidCrystal_I2C library https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads/LiquidCrystal_V1.2.1.zip

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LCD Keypad Shield

A display and buttons shield (but BTW: have you checked other Displays on this site?) well suited as the human interface for a number of “compact design standalone” projects.


Similar to already described 16×2 LCD module (using the same display), but with 6 built into the shield buttons (RESET, SELECT; and 4 directions: LEFT, UP, DOWN, RIGHT).

The shield leaves a lot of pins at your disposal. Used pins are only:

Analog 0 Button (select, up, right, down and left – see the code comments)
Digital 4 – 7 DB4 – DB7
Digital 8 RS (Data or Signal Display Selection)
Digital 9 Enable
Digital 10 Backlit Control

So the user has free access to Analog 1-5, and Digital 0-3 and 11-13. Out of these, the most important are 0 and 1, which can be used as RX and TX, 3 and 11 with are PWM capable, as well as standard LED 🙂 output on digital pin 13.

Also whole ISCP connector, which is normally blocked by the shield body is repeated on the side.

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