My Custom A31s Board RAM Problem

Banana Pi SBCs design BPI-M2(A31s)
1

Hello to everyone.

I designed a custom board with AllWinner A31s. I referenced BPI-M2-V3_1 open source schemas. The PCBs were produced and I placed the materials. I had a soldering problem for a while.then 3 boards worked without problems.

I used the axp221s power chip. The voltages on the pcb are correct(and I can change the voltage values with Uboot). I connected the computer with usb. I have previously compiled linux-sunxi sun6i uboot(I did not change any settings). I use the sunxi tools to install uboot. Using sunxi-fel, I tried loading uboot like this:

        sunxi-fel.exe uboot u-boot-sunxi-with-spl.bin

but the error was in case of ram init. Data coming from uart debug :

U-Boot SPL 2017.11 (Feb 03 2018 - 12:58:59)

DRAM:Training error initialising DRAM

resetting …

I added printf to debug uboot source code, and I compiled again. I see the reset in mctl_channel_init function.

I using 2 x 256MB IS43TR16128B-125KBL DDR3 1.5v DDR3 reference voltage ~0.750v

I use 256MB of NAND flash. My next target is to boot using nand flash.But I did not finish the ram end. Can you help me? Is the problem hardware or software? Are there places I need to organize in uboot source code? thank you everyone…

2

My answer to my question. this problem is the problem of ram soldering.

My advice to those who want to design a special board; Be careful during the cpu selection phase. I made a mistake using a31s. GPU and sound problems. The existing linux kernels did not provide a solution. Do not start with this if you do not have sufficient knowledge. Use the popular cpu if you want to start such a project. (eg A20)The board circuit you designed to get a circuit that is more pre-tested. for example (bpi-m1). If you use different circuitry, you may have to deal with dts and fex files. If you don’t have enough information, all of this can exhaust you.

Thanks…

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