Troubleshooting a board that won't boot

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Steps and helpful hints to getting a booting system

SD Card Problems

Creating the micro SD card for Wandboard can lead to problems. Here are some hints.

Use the correct microSD slot

The Wandboard will only boot from the microSD card slot on the module. The microSD slot on the baseboard is only for storage.

Premature card ejection

Be patient. Ejecting the card too quickly from your host computer can cause failures because the writing process might not have completed.

Conflicting processes writing to your card

If you are using a Linux host system to write the SD card (typically using dd), ensure that any existing partitions on the card are not mounted before you write to the card. Simply unmounting the card partitions should be enough. This is usually a problem on Ubuntu desktop distributions when writing to a previously formatted card.

Serial Cable

A serial cable is an invaluable tool to help you get started. Wandboard requires a NULL modem serial cable (where TX and RX are reversed). Usually these cables have a DB-9 mail connector on both ends. Use a terminal program such as minicom, putty, or screen (on Linux) or Teraterm or Hyperterminal (on Windows) to see the console output when booting your Wandboard.

The settings for the serial port are:

  • 115200 kbits/sec
  • 8 data bits
  • No parity
  • 1 stop bit

This is sometimes abbreviated as 115200-8-n-1

No hardware flow control is used.

If there is no output on the serial port, this does not mean the Wandboard is defective: the Wandboard itself has no bootloader and won't write anything to serial on its own. It's more likely that there is a problem with the micro SD card.

There have been reports of difficulties accessing the serial port from the Mac; the pl2303 driver used by many USB/serial dongles may be faulty. Try using Linux instead to connect, e.g:

screen /dev/ttyUSB0 115200 8N1

Verify that the i.MX6 is functional using USB OTG

Without inserting an SD card into your Wandboard, you may use a USB OTG cable to verify that the i.MX6 processor is operating.
Steps

  1. Start by connecting the USB OTG cable into mini USB connector on your Wandboard.
  2. Connect the other side to your development computer.
  3. Apply power by connecting power adapter to your Wandboard.
  4. It should appear as a "Freescale Semiconductor" device. In linux you can do "lsusb" to see the attached devices.