This is a long-term experiment running thirteen RTCs for some time in order to see how they live up to their specifications.
Ground truth is delivered by a DCF77 receiver and the deviation is measured in msecs every day at midnight. In addition, temperature is measured every hour. All that is stored in a serial EEPROM with space for 1024 days. The plan is to let the experiment for a year or two.
The RTCs that will participate are:
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DS1307,
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DS1337,
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DS3231SN,
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DS3231M,
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MCP79410,
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PCF8523,
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PCF8563,
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RS5C372,
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RV-3028,
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RV-3032,
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RV-8523,
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RV-8803, and
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SD2405.
This is how it looks before I started to connect the RTCs to the I2C multiplexers and the MCU.