Creating a custom Linux BSP for an ARM Cortex-A9 SBC with Yocto 1.8 - Part III

In part III of this guide, the installation of the final image to the SD card will be covered.  The SD card will then be booted on the target.  Finally, audio recording and playback will be tested.

Part III of this guide consists of the following sections.

1. Write the GNU/Linux BSP image to an SD card.
2. Set the physical switches on the RioTboard (Internet of Things) to boot from the uSD or SD card.
3. Connect the target to the necessary peripherals for boot.
4. Test audio recording, audio playback, and Internet connectivity.

1.  Write the GNU/Linux BSP image to an SD card

At this point, the build should be complete, without errors.  The output should be as follows.

 real 254m28.335s
 user 737m9.307s
 sys 133m39.529s

Insert an SD card into an SD card reader, connect it to the host, and execute the following commands on the host.

 host]$ cd $HOME/src/fsl-community-bsp/build /tmp/deploy/images/imx6dl-riotboard
 host]$ sudo umount /dev/sd<X>
 host]$ sudo dd if=bsec-image-imx6dl-riotboard.sdcard of=/dev/sd<X> bs=1M
 host]$ sudo sync

2. Set the physical switches on the RioTboard to boot from the uSD or SD card.

For booting from the SD card on the bottom of the target, set the physical switches as follows.

SD (J6, bottom) 1 0 1 0 0 1 0 1

For booting from the uSD card on the top of the target, set the physical switches as follows.

uSD (J7, top) 1 0 1 0 0 1 1 0

3. Connect the target to the necessary peripherals for boot.

There are two options

Option 1

Connect one end of an ethernet cable to the target. Connect the other end of the ethernet cable to a hub or DHCP server.  

Connect the board to the host computer via the J18 serial UART pins on the target.  This will require a serial to USB breakout cable.  Connect TX, RX, and GND to RX, TX, and GND on the cable. The cable must have an FTDI or similar level shifter chip. Connect the USB end of the cable to the host computer.

Connect the speakers to the light green 3.5 mm audio out jack and the microphone to the pink 3.5 mm MIC In jack.

Connect a 5V / 4 AMP DC power source to the target.

Run minicom on the host computer. Configure minicom at 115200 8N1 with no hardware flow control and no software flow control. If a USB to serial cable with an FTDI chip in it is used, then the cable should show up in /dev as ttyUSB0 in which case, set the serial device in minicom to /dev/ttyUSB0.

If this option was chosen, drop into U-boot after power on by pressing Enter on the host keyboard with minicom open and connected.

If enter is not pressed after power-on, the target will boot and a login prompt will appear.

A login prompt will not appear.

Option 2

Connect one end of an ethernet cable to the target. Connect the other end of the ethernet cable to a hub or DHCP server.  

Connect a USB keyboard, USB mouse, and monitor (via an HDMI cable) to the target.

Connect the speakers to the light green 3.5 mm audio out jack and the microphone to the pink 3.5 mm MIC In jack.

Connect a 5V / 4 AMP DC power source to the target.

A login prompt will now appear.

4. Test audio recording, audio playback, and Internet connectivity

Type root to log in to the target. The root password is not set.

Execute the following commands on the target

 root@imx6dl-riotboard: alsamixer 

Press F6.
Press arrow down so that 0 imx6-riotboard-sgtl5000 is highlighted.
Press Enter.
Increase Headphone level to 79<>79.
Increase PCM level to 75<>75.
Press Tab.
Increase Mic level to 59.
Increase Capture to 80<>80.
Press Esc.

 root@imx6dl-riotboard: cd /usr/share/alsa/sounds
 root@imx6dl-riotboard: aplay *.wav 

A sound should be played through the speakers.

 root@imx6dl-riotboard: cd /tmp
 root@imx6dl-riotboard: arecord -d 10 micintest.wav

Talk into the microphone for ten seconds.

 root@imx6dl-riotboard: aplay micintest.wav

A recording should play through the speakers.

 root@imx6dl-riotboard: ping riotboard.org

An ICMP reply should be received.