DS3231 reads are not consistant

[wyojustin]

HW: ClockIOT First 5 complete protos (and no LED protos)
SW: ClockIOT (9/26/2018)

Problem:
When DS3231 is set, and subsequently read, the values can be very different.

OUTPUT: CASE 1, the absolute difference between ntp and ds3231 is greater than 5 seconds, so update ds3231. After update the incorrect value is read. A second later, the ds3231 is off my a large value, so reset it again with same result

abs diff: 111011100111111110110110000
master: 1011011101010110001110000000001
backup: 1010100001101110001111001010001
backout wrong: 1010100001101110001111001010001
SET THE BACKUP to master: 1011011101010110001110000000001
got: 1010100001101110001111001010001

abs diff: 111011100111111110110110001
master: 1011011101010110001110000000010
backup: 1010100001101110001111001010001
backout wrong: 1010100001101110001111001010001
SET THE BACKUP to master: 1011011101010110001110000000010
got: 1010100001101110001111001010001

[wyojustin]

Good news: I rejiggered the code to only request time from the ds3231 every 10 minutes (rather than several times per second) .
so the problem is reduced by a factor of 1000
for the long term fix, this looks like it is in the right area:

espressif/arduino-esp32#912

[wyojustin]

Clock is now working fine. Issue closed.