Converting a number to tens and ones comparison

[Kenrix2]

This is a comparison of three different digit conversion methods to get the tens and ones digit which I use for two digit
seven segment displays (both led and lcd glass). I needed to determine the best method to use depending on my application.
Here are the results of my comparison tests which I thought I would share. The different conversion programs are attached.

Using IF less than to determine the digits
Pros:
good conversion speed, 21us to 62us (average is about 43us, the higher the number the longer it takes)
It simulates in Flowcode
Uses little ROM space
Cons:
Conversion time is not consistent
Takes up a lot of your screen real estate
Takes awhile to setup in your program

Using a ROM lookup table
Pros:
Does not not take up much screen real estate in you program
Somewhat easy to add to your program
Conversion time is the same for any value
Cons:
Slow conversion speed, 110us
Does not simulate in Flowcode (It might in V6 but I am not sure)
Uses a lot of ROM space

Using a RAM lookup table
Pros:
Excellent conversion speed, only 32us (as expected this is the fastest)
It simulates in Flowcode
Conversion time is the same for any value
Cons:
Takes up a lot of RAM (obviously)
Takes awhile to setup
Takes up a bit more of your screen real estate than the ROM LUT
Adds a whopping 207us to the power on reset time vs the others
Uses a lot of ROM Space

If anyone has a another method to convert a number (0 to 99) into tens and ones digits, and wouldn't mind sharing, I would
like to see it.

[Spanish_dude]

There's another, easy and short, method you missed:

Code: Select all

int number, ones, tens;

if (number >= 100)
    number = 0;
else
{
    ones = number % 10; // (MOD)
    tens = number / 10;
    number++;
}

- Nicolas

[Kenrix2]

Thank you for your response Spanish_Dude. The method you posted is probably the simplest and easiest to use. It can also be put into a normal Flowcode calculation box for simulation within Flowcode. It's a great default method. However, a speed test shows it is dead last at 260us. Ouch!

[Spanish_dude]

Yes, multiplications and divisions are very slow.

- Nicolas