1Hz Square Wave/Clock Generator

[varunkoganti]

Hi Everybody,

The project is simple, I am trying to build a digital clock, this requires a 1Hz timing.
My idea for the 1 Hz timing is to use a 32.768KHz crystal and then count the crystal using a 15-bit counter(2^15 = 32768), this would give me 1 sec.

I built up the circuit (Pierce oscillator),
Capacitors = 18pF.
Rfeedback = 1M ohm.
The inverter is a 74HC04 by TI(Texas Instruments).

I tried measuring the wave form using my arduino's digital read and this is what i keep getting.

I need help, is this actually correct, I do not have an oscilloscope.

[perieanuo]

for 1HZ someone don't need a 1GHz capable scope, almost all multimeters today have ac freq function
to answer your question, we need oscillator's schematics, maybe osc photos, interface schematics with ardu, ardu code. not easy to digg into something with no info at all

[Zero999]

The 74HC04 isn't the best IC to use for a crystal oscillator. The 74HCU04 is more suitable. The 74HC04 has buffered outputs. Each inverter really has three logic inverters connected in series. When configured in the linear region, the extra gain and phase shift can cause it to oscillate at an unpredictable high frequency.

Why not use the 74HC4060? It contains an unbuffered gate and a counter, to give a range of lower frequencies, which are easier to use.

There are also ICs, which are specifically designed to make a crystal oscillator such as the :74LVC1404 and 74LVC1GX04.
https://www.ti.com/lit/ds/symlink/sn74lvc1404.pdf
https://assets.nexperia.com/documents/data-sheet/74LVC1GX04.pdf

[varunkoganti]

So i have looked into the suggested ICs, unfortunately I couldn't find DIP version of 74lv1404 at my location, I have had a look into 74HC4060, which was available.
I made up the schematics. I will order these parts and try it out as per below on a breadboard.

[retiredfeline]

For the CD4060 I've used 10M for the resistor and it works.