rodan / ds3234 Goto Github PK

Hi, thanks for the great library.
I notice that nearly all routines for reading and writing the time follow the same process that "could" lead to invalid time/date reading. From the PDF it says the register value is copied upon CS to prevent rollover screwing with the time/date.
My suggestion is to Set CS, read/write all required registers then unset CS.
I know that it would probably be rare to be reading the time/date regs during a rollover.
But to be the best maybe a few adjustment to the code????

From the PDF ...
When reading or writing the time and date registers,
secondary (user) buffers are used to prevent errors
when the internal registers update. When reading the
time and date registers, the user buffers are synchronized
to the internal registers on the falling edge of CS
or and when the register pointer rolls over to zero. The
time information is read from these secondary registers,
while the clock continues to run. This eliminates the
need to reread the registers in case the main registers
update during a read.

Have you tried it on a ESP8266?
I have it working using a bit-banged version not the inbuilt SPI library.
The seconds seem to read ok, but the subsequent reads dont get the right data.
I did have some luck by setting CS, read all 7 regs then unset CS.
Any thoughts?

1900.00.00 00:48:08
1900.00.00 00:52:13
1900.00.00 00:48:18
1900.00.00 00:52:23
1900.00.00 00:48:28
1900.00.00 00:52:33
1900.00.00 00:48:38
1900.00.00 00:52:43
1900.00.00 00:48:48
1900.00.00 00:52:53
1900.00.00 00:48:58
1900.00.00 12:53:03

Line 76:

if (t.year > 2000) {

should be

if (t.year >= 2000) {

This is the output im getting off the example with 2 changes (cs set to 7 and "pinMode(10, OUTPUT);" since pin 10 has to be output for SPI for some reason...):

GET time
1917.05.20 68:24:45
1917.05.20 68:24:50
1917.05.20 68:24:55
1917.05.20 68:25:00
1917.05.20 68:25:05
1917.05.20 68:25:10
1917.05.20 68:25:15
1917.05.20 68:25:20
1917.05.20 68:25:25
1917.05.20 68:25:30
1917.05.20 68:25:35
1917.05.20 68:25:40
1917.05.20 68:25:45

Month, day and seconds seem to be right. First 2 digits of Year and first digit hour obviously not, minutes are 10 too low, so first digit.
Correct output would be eg:
2017.05.20 18:35:45 (where this is GMT and i would currently have GMT +2h here, but thats no issue since the problem exists with summer time saving anyway...

Edit:
If the time is set outside of this library I can correctly read it back with the this library - only with 1917 instead of 2017 as the year:
1917.05.20 21:39:31
1917.05.20 21:39:36
1917.05.20 21:39:41
1917.05.20 21:39:54

This post fixed the problem, you may want to update the library/examples to reflect this.
Thanks for this library
http://forum.arduino.cc/index.php?topic=309872.0