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Topic: RTC & Arduino NANO not working :( (Read 194 times) previous topic - next topic

Schmerol

Hi

Please help me, i don't get it.

i made a simple sketch, with which i can set a fan on low or highspeed for a quiet sleep.
now, it is working fine on my arduino leonardo. but the rtc is not working on the nano.

i have some arduino nanos and they dont have the SDA & SCL pins.
on the internet i found various tutorial how you have to connect the SDA % SCL to Pin A4 & A5 of the Nano

but yeah, it doesn't work. i can't even ask myself the question, what the reason could be. i'm just new to this all.
maybe a damaged arduino nano?

thank you for any help!

ps.
the RTC is an Grove Seeed RTC

http://wiki.seeed.cc/Grove-RTC/

CrossRoads

SDA & SCL come from A4 & A5 on '328P based boards. They are duplicated as SCL & SDA on the Uno for example.

Do you have 4.7K resistor from SCL to 5V, and from SDA to 5V? Those are needed for I2C. I don't know if they are included on the Grove-RTC.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Schmerol

SDA & SCL come from A4 & A5 on '328P based boards. They are duplicated as SCL & SDA on the Uno for example.

Do you have 4.7K resistor from SCL to 5V, and from SDA to 5V? Those are needed for I2C. I don't know if they are included on the Grove-RTC.
hey, thank you very much for the input.
so how is that wiring exactly? just normal SDA to A4 and SCL to A5, AND 5V over 4.7k resistors as well to these analog pins.
i tried this, but it is not working.

OR SDA, SCL plus 5V together over 4.7k pins? i don't really understand that...

the grove-website says: "The RTC module is based on the clock chip DS1307, which supports the I2C protocol"
http://wiki.seeed.cc/Grove-RTC/

so... does that mean there are resistors already on the RTC?

this is way beyond my understanding of electronics:)

PaulRB

#3
Apr 22, 2017, 08:42 am Last Edit: Apr 22, 2017, 08:56 am by PaulRB
4K7 Pull-up resistors are included on the Grove module, so that's not the problem. Schematic.

You should connect A4 to SDA, A5 to SCL, 5V and ground to the Nano. Then try running the i2c scanner sketch and watch the serial monitor.

Schmerol

4K7 Pull-up resistors are included on the Grove module, so that's not the problem. Schematic.

You should connect A4 to SDA, A5 to SCL, 5V and ground to the Nano. Then try running the i2c scanner sketch and watch the serial monitor.
Thank you PaulRB, cool tool.
unfortunatelly no I2C found...
i tried another nano i have, it works!

i really only want to use the leonardo in the project as last alternative. for the final projects i specially bought the nanos, as small controllers, and the leonardo as sketching-board.

so, very happy this works now. thank you both!

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