The DS1302 library examples didn't work in Arduino IDE.

[mianqi2016]

I tested your DS1302 in Arduino IDE, the "ds1302" and "datecalc" were all not work,

the former prompted:

'DS1302' does not name a type,

the latter:
'const class DateTime' has no member named 'tostr'

Sorry, I confused this library with another "RTCLib by NeiroN", the prompt was:RTC lost confidence in the DateTime!

[Makuna]

What Arduino Board are you using?

What sketch are you using?
Include at least several lines of the serial output.

The most common cases of this message are the pins are not connected correctly and/or the onboard battery is dead.
https://github.com/Makuna/Rtc/wiki/FAQ-%235

[mianqi2016]

I found the reason:

`
//ThreeWire myWire(4,5,2); // IO, SCLK, CE

ThreeWire myWire(17,16,26); // IO, SCLK, CE

// Since the board in experiment was Espduino

// (Arduino UNO based on ESP32)

// so pin-numbers according to Arduino UNO(4,5,2)

// are IO(17,16,26)
`

[mianqi2016]

I used a new components of breadborad+DS1302+Crystal and then it was OK, thanks for your answer to my issue. I think you were right - " the pins are not connected correctly " although I haven't start to find why the former group didn't work. Your code is clear and would be more useful when added the weekday info. Thanks.

[Makuna]

Just confirmed it works with ESP32.

ThreeWire myWire(17,16,5); // IO, SCLK, CE

This equates to in order, as labeled on my ESP32 Dev board; TX2, RX2, and D5.
Note my RTC module labels CE as RST.
ESP boards sometimes label D pins that don't match their GPIO number.

Also note, the spec sheet for the chip states to make sure the crystal is backed by GND plane and the wires leading to it as also well shielded.

[mianqi2016]

I tried it just now, it works:
ThreeWire myWire(27,16,17); // IO, SCLK, CE

[mianqi2016]

[mianqi2016]