This is a new menu item class to use with LcdMenu from forntoh. This item class displays and make changeable int values in range with defined minimal and maximal values. Negative values are also possible.

Include LcdMenu.h and ItemProgressIntMinMax. Make sure that the library required for the interface of your LCD display is also available.(LiquidCrystal.h or LiquidCrystal_I2C.h).

#include <ItemProgressIntMinMax.h>
#include <LcdMenu.h>

const uint8_t LCD_ROWS = 2;
const uint8_t LCD_COLS = 16;
LcdMenu menu(LCD_ROWS, LCD_COLS);

Create your own menu with the menu item class ItemProgressIntMinMax (and other). The parameters of the new class item in order are:

• key - The menu item displayed text.
• measure - The measure of menu item value is printed behind them. Can be NULL (not displayed).
• minval - The minimum that can be the item value.
• maxval - The maximum that can be the item value.
• start - The item value, when the menu is created.
• stepLength - The step value with which the item value is incremented or decremented by call menu.right() and menu.left().
• callback - The function that is called when editing the menu item is finished.

// Declare the menu call back functions
void bassCallback(uint16_t value);
void middleCallback(uint16_t value);
void trebleCallback(uint16_t value);
void balanceCallback(uint16_t value);
void menuExitCallback();

// Define the main menu
MAIN_MENU(
    ITEM_PROGRESS_INT_MINMAX("Bass   ", "dB", -21, 6, 0, 1, bassCallback),
    ITEM_PROGRESS_INT_MINMAX("Middle ", "dB", -21, 6, 0, 1, middleCallback),
    ITEM_PROGRESS_INT_MINMAX("Treble ", "dB", -21, 6, 0, 1, trebleCallback),
    ITEM_PROGRESS_INT_MINMAX("Balance", NULL, -21, 21, 0, 1, balanceCallback),
    ITEM_COMMAND("Exit", menuExitCallback)
);

void setup()
{
    menu.setupLcdWithMenu(0x27, mainMenu);     // LcdMenu use the LiquidCrystal_I2C library
}

To set the value of the menu item dynamically call for example:

menu[1]->setProgress(-5);    // set the bass menu item value to -5dB
menu[3]->setProgress(4);     // set the treble menu item value to 4dB
menu.update();

The LcdMenu core library works internally with unsigned data types. Therefore, using negative values ​​involves some tricks.

It is therefore necessary to cast the return value, this is from type uint16_t, in the signed type int16_t.

void bassCallback(uint16_t value) 
{
    Serial.println("Bass", (int16_t)value); 
}

In order to get the base class to work with negative values, it was necessary to redefine the two macros MIN_PROGRESS and MAX_PROGRESS.

For more Informations check the examples section and the github repro from forntoh.