Tag Archives: ds3231

STM32F411 RC Calibration Using a DS3231 TCXO 1HZ Signal

STM32 RC oscillator frequency varies from one chip to another due to manufacturing process variations. ST claim each device is factory calibrated for 1% accuracy at 25°C. Thus, after reset this factory calibration value is loaded in the HSICAL[7:0] bits … Continue reading

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STM32F411 Nucleo I2C DS3231 1Hz Square Wave with External Interrupt

Bare metal like. A very basic demonstration of STM32 I2C communications with a DS3231 chip (in the form of a ChronoDot). The program uses I2C to communicate with the DS3231 chip. It sets the DS3231 date and time, and commands … Continue reading

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Modified DS3231 ChronotDot

Version 1.0 of the ChronoDot has a critical flaw. It does not fit on a standard breadboard. Because of it’s round shape, one can’t use pins outboard of the PCB. To fix this shortcoming, I decided to shave it down … Continue reading

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Arduino Crystal vs. DS3231 TXCO

I tested the accuracy of a crystal on one of my Arduino Duemilanove (ATmega168 version) boards. I compared the crystal against a TXCO (ChronoDot). The following graph shows the results. Note: I’m not sure about the “3 glitches” present in … Continue reading

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