Real Time Clock Module DOA

Other Miscellaneous
1

I just received the real time clock module based around the DS1307 and it appears to be dead on arrival. The I2C interface is non-responsive to clean looking read/write commands (slave address 0x68). When I probe the X2 oscillator pin, there is only DC out (not oscillating). I’m assuming that I should see some activity on that pin if the oscillator circuit within the chip is functioning properly.

The battery measures 3.0V so it looks good. I took the crystal off the board and tested it in a test circuit I built. It resonates at 32.768kHz as expected. That pretty much leaves the IC as the issue.

All this testing was done with a 5V source connected to the board.

Does anyone have any other suggestions for troubleshooting before I open a return request?

2

Nope, those are the same steps I’d suggest…sounds like a dead IC - head over to www.sparkfun.com/returns if purchased from us, or contact your vendor if purchased elsewhere for a replacement

3

Well this is embarrassing. It turns out it was user error. I was using an FT232H to interface with the RTC module and I didn’t realize that I needed to connect ADBUS1 and ADBUS2 to SDA (one drives the line and the other reads the line). I only had ADBUS1 connected which explained why I was able to drive the correct waveform on the bus but not read the slave’s ACK.

Also, after enabling the oscillator via an I2C command the X2 pin oscillates at 32.768kHz.

Everything is working as it should.