RTC not responding

[my_abousamra]

Posted on December 28, 2015 at 11:06

Hi there,

I'm writing a driver for m41t83 RTC IC. I'm trying to start communication with it over I2C (fast mode) and I have no response from the RTC (always get NACK).I don't know what might cause the problem I send the RTC address 0x68 after the start condition and send write bit but receive a NACK.Forgive me if it is not the suitable place to post this question as I can't find better section. #rtc #i2c #m41t83

[Tesla DeLorean]

Posted on December 28, 2015 at 16:16

Forgive me if it is not the suitable place to post this question as I can't find better section.

I'm not sure there is a support group for I2C users. Are you using it with an STM32 micro-controller, or something else? Your question lacks some context. Make sure you are using Open-Drain pin drivers, with external pull-ups. Understand the I2C peripheral and library for your micro-controller. Some will refer to the address as 0x68, others as (0x68 << 1), the 7-bits are the high-order bits on the bus. The NACK indicates the IC doesn't recognize that it's being addressed. Look at the signalling with a Logic Analyzer, present that plot, and any software or circuit diagrams that might assist.

[my_abousamra]

Posted on December 29, 2015 at 11:18

I was looking for a group for RTC ICs to get assist but I didn't find any one here.

This RTC data sheet mentions that its address is 0xD0 and the data figures show the address is 0x68 and I use pull up resistors for the clock and data buses.