Hi,
We have designed two variants of SOM based SBC boards for my application. The SOM we bought from the Calixto, Banglore. One variant is to interface the 7inch touch screen based LCD which will be located in the driver desk of the train set and other variant is to interface the 18.5 inch LCD display which will be located in the passenger area to display the route related information. For both the boards we are having the LVDS interface and we have selected the boot source as SD card.
We are facing one problem in both variants of PCBs. Initially these boards are worked well and after some days these PCBs are not get booted. we are receiving 'C'(8No.s) from the console port afterwards we are not get anything on the console port. We have some mismatch in the track lengths of the data lines and clock signal of the SD card in these PCBs. But my doubt is already I have done other board long back for other project, there also the track lengths are not matching even though Im not getting any problem till now and here we are getting problem in 2 boards out of 6 boards.
Today we have tested the booting from serial port by loading the u-boot-spl.bin and u-boot.img files from the serial port using xmodem1k and ymodem protocols. We are getting upto U-Boot now. After that mmc dev command is given resulting that the message "card did not respond to voltage select".
Please let us know what could be the issue also let me know if any further clarifications are required.
The track lengths of the PCBs are as below:
Variant1:
Data 0 - 72.39 mm
Data 1 - 72.31 mm
Data 2 - 72.82 mm
Data 3 - 72.82 mm
Clk - 78.34 mm
CMD - 66.78 mm
Variant 2:
Data0 - 73.68 mm
Data1 - 73.29 mm
Data2 - 73.48 mm
Data3 - 73.46 mm
CMD - 56.06 mm
Clock - 87.13 mm
