TE0720 RTC and custom carrier

[S20]

Hi - I have a standalone application written which uses the RTC on the TE0720 (-03-CF). It is functioning correctly when plugged into a TE0703-05 carrier. When I plug it into my custom carrier it fails to communicate with the RTC.

The carrier is basic at this stage, there are no devices on my carrier using I2C. JB1 pins 94,96 (MIO11/10) are floating. No customisation to MIO defaults.

Given the RTC is on the SoM I'm not sure what interface pins (on JB1/2/3) could be causing this issue.

[JH]

Hi,
can you scan bus with i2cdetect? What did you see?
we provide also reference design with linux, so you can use this one to test(prebuilt boot.bin and image.ub are included):
https://wiki.trenz-electronic.de/display/PD/TE0720+Test+Board
This design use also RTC, can you check if it's recognize the RTC?
https://wiki.trenz-electronic.de/display/PD/TE0720+Test+Board#TE0720TestBoard-Linux

br
John

[Oleksandr Kiyenko]

Hi,

RTC chip is not connected to Zynq MIO, it routed like
[Zynq MpSoC - EMIO - PL]-{X1,X5,X7 signals}-[U19 System controller]-{SCL,SDA}-[U20,U22]
Only external signals which can affect to this path are VBAT_IN and 3.3V power. Please check it.

Best regards
Oleksandr Kiyenko

[S20]

Thank you for your suggestions and information. The issue was tracked down to be a noisy 3.3V line during power up. An external SMPS was being used in bench testing which was the route of the noise.