Hello there,
I was recently testing a real time clock (RTC) breakout board with the DS3231 chip on it, and it also has a 32k bits EEPROM chip.
So far so good, the RTC is doing less than 1 second error in 8 hours, but we'll see how it goes after a longer time period.
My temperature is fairly constant around room temperature, and 2 parts per million translates to about 1 minute per year which is about 5 seconds per month which is about 0.1752 seconds per day, so it's hard to measure over only 8 hours, but i've seen much worse than this is showing already. Because it works pretty well over 8 hours it will be more than good enough for my little dual timer project, which is intended to count days, hours, minutes, seconds over maybe a week at the longest. So the error over a week should not be more than about 1.2 seconds, but again, we'll see how this goes.
The nice thing is, it has a battery backup on board, so turning off the power does not lose time which makes experimentation very easy because the power can be shut down for days at a time, then the time can be checked at the later date and compared to a known good clock. This will make it easy to check after say a week.
I was also surprised that the library downloaded for it WORKED the first time! That's not always the case as many people know. So there was very little rework to do except maybe changing the display format a little and adding a blink LED to indicate activity even when the time is not being displayed.
I have not gotten to try the on board EEPROM though yet, which is a 32k bit unit which translates to 4096 bytes of EEPROM, 8 bits per byte. That provides for a little extra non volatile storage space.
Some good points about this breakout board:
1. 2 parts per million stability translates to about 1 minute per year, about 1.2 seconds per week.
2. Has on board EEPROM, 4096 bytes.
3. Runs on 3.3v or 5v or anything in between.
4. Has on board battery backup, rechargeable Li-ion cell which will keep time for years on a full charge due to the low current requirement during power down.
5. I2c interface which allows other I2C devices to operate off of the same two microcontroller pins, although some might prefer SPI.
6. Fairly small, the whole board is only about 0.75 inches by about 1.5 inches.
Accuracy looks good so far, but i'll post more at a later date once i have more time data.
I was recently testing a real time clock (RTC) breakout board with the DS3231 chip on it, and it also has a 32k bits EEPROM chip.
So far so good, the RTC is doing less than 1 second error in 8 hours, but we'll see how it goes after a longer time period.
My temperature is fairly constant around room temperature, and 2 parts per million translates to about 1 minute per year which is about 5 seconds per month which is about 0.1752 seconds per day, so it's hard to measure over only 8 hours, but i've seen much worse than this is showing already. Because it works pretty well over 8 hours it will be more than good enough for my little dual timer project, which is intended to count days, hours, minutes, seconds over maybe a week at the longest. So the error over a week should not be more than about 1.2 seconds, but again, we'll see how this goes.
The nice thing is, it has a battery backup on board, so turning off the power does not lose time which makes experimentation very easy because the power can be shut down for days at a time, then the time can be checked at the later date and compared to a known good clock. This will make it easy to check after say a week.
I was also surprised that the library downloaded for it WORKED the first time! That's not always the case as many people know. So there was very little rework to do except maybe changing the display format a little and adding a blink LED to indicate activity even when the time is not being displayed.
I have not gotten to try the on board EEPROM though yet, which is a 32k bit unit which translates to 4096 bytes of EEPROM, 8 bits per byte. That provides for a little extra non volatile storage space.
Some good points about this breakout board:
1. 2 parts per million stability translates to about 1 minute per year, about 1.2 seconds per week.
2. Has on board EEPROM, 4096 bytes.
3. Runs on 3.3v or 5v or anything in between.
4. Has on board battery backup, rechargeable Li-ion cell which will keep time for years on a full charge due to the low current requirement during power down.
5. I2c interface which allows other I2C devices to operate off of the same two microcontroller pins, although some might prefer SPI.
6. Fairly small, the whole board is only about 0.75 inches by about 1.5 inches.
Accuracy looks good so far, but i'll post more at a later date once i have more time data.