Saturday, June 15, 2024

ESP32 RTC Millisecond clock display

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Clock is my fascination. I have made clocks of several variety & themes but I never made any clock which have millisecond display. The reason being the huge load of processing power which always falls short for the demand of fast changing display.

However, the first success came when I successfully could run the 3.5” ILI9488 TFT display on 8 bit mode with ESP32. On 8 bit mode it needs 12 GPIO pins to run the display and it is really very fast and there lies the success of this millisecond display clock.

The “3.5 inch TFT LCD Touch Screen Display Shield for Arduino Uno” is available at & for INR:1400 only.


Although the TFT display fits very easily on an Arduino UNO but this millisecond display is not possible on Arduino UNO as it lacks the computing power.

The TFT ILI9488 pin connections detail is like this.

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TFT Pin ESP32 Pin TFT Pin ESP32 Pin
3.3V 3.3V D5 4
Gnd Gnd D6 5
D0 7 D7 6
D1 8 CS 15
D2 1 DC 0 [keep empty]
D3 2 RST 14
D4 3 WR 17



The time is calculated from the RTC DS3231. This RTC have capability of measuring temperature as well which is also displayed on the TFT. The time duration between consecutive seconds is divided by 1000 to calculate the millisecond and displayed on the TFT. The simple line drawing is tricked to created thick line which is put into variable function.

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Aftermath: The project is built up on a general purpose PCB. The power supply is a 5 volt smart phone power supply. The cost of the project is about INR:2000 [$25 USD]

Download Source Code


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