3. Using the DEVKIT#

This chapter provides instructions for using HAIKOU CB-MINI-ITX, such as booting and how to configure and use I/O peripherals (e.g. serial console, Ethernet).

3.1. HAIKOU CB-MINI-ITX Overview#

An overview of the available connectors and devices on HAIKOU CB-MINI-ITX is shown below.

_images/baseboard_with_module_screws_top.png

Fig. 3.1 HAIKOU CB-MINI-ITX with PUMA SOM-RK3399-Q7#

3.2. Power Supply#

HAIKOU CB-MINI-ITX can operate with a single 12V DC power supply.

_images/board_connect_power.png

Fig. 3.2 12V Power connector#

Power can be controlled manually from the board using the Power control buttons and switches, located on the lower right side of the board (see HAIKOU CB-MINI-ITX Overview).

Depending on the setting of Normally On / Normally Off switch, HAIKOU CB-MINI-ITX will boot as soon as it receives power.

3.3. Control Buttons and Switches#

The control buttons provide the following functionality:

  • Power toggles the module power supply

  • Reset triggers a module reset

  • Batlow, Sleep and Wake are routed to GPIOs on the Q7 module

Several slide switches are located on the lower left:

  • LID is routed to a GPIO on the module, simulates lid open/close.

  • Normally On / Normally Off, as described above, sets the state after power loss.

  • BIOS Disable / Normal Boot forces SD card boot or the normal boot order, respectively.

3.4. CPU Fan#

Operation in high environmental temperatures may require a CPU fan. The fan connector is located next to the bottom right corner of the Q7 expansion area (see board overview).

_images/baseboard_FAN.png

Fig. 3.3 Fan connector#

Note

The fan is only necessary in high ambient temperatures. Under normal conditions, PUMA SOM-RK3399-Q7 operates passively cooled.

3.5. Boot Order#

The used boot order of PUMA SOM-RK3399-Q7 depends on the value of the BIOS_DISABLE# signal. On HAIKOU CB-MINI-ITX this signal can be set using a slider switch, with the two positions labeled Normal Boot, and BIOS Disable.

As shown in the table below, the BIOS Disable position disables both on-module storage devices:

Normal Boot

BIOS Disable

1

SPI NOR flash

SD card

2

eMMC storage

USB loader

3

SD card

4

USB loader

If no bootloader is found on any storage device, PUMA SOM-RK3399-Q7 will go into USB loader mode where it shows up as a USB device on the USB-OTG port.

The electrical state of the BIOS_DISABLE# signal for both slider positions is shown below:

Slider Position

BIOS_DISABLE# signal

Normal Boot

Floating (on-module pull-up to 1.8V)

BIOS Disable

GND

3.6. USB Serial Console#

HAIKOU CB-MINI-ITX contains an on-board Silicon Labs CP2102N USB-serial converter. Connect the included Micro-USB cable to the Micro-USB jack labeled USB-UART Bridge:

_images/baseboard_USB_UART.png

Fig. 3.4 USB UART#

The serial converter does not require additional drivers on Windows and Linux.

For Mac OS, drivers are available from Silicon Labs: http://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers

PUMA SOM-RK3399-Q7 has two external UARTs:

  • UART0 is, by default, used for the serial console for interactive login.

  • UART1 is unused by default and can be freely used for machine-to-machine communications or other purposes.

The switch UART0 / UART1 cross-switches UART0 and UART1 between the RS232 / RS485 jack and the onboard USB-serial converter:

Switch Position

RS232 / RS485 jack connected to:

USB-serial converter connected to:

UART0

UART0 (interactive console)

UART1

UART1

UART1

UART0 (interactive console)

For interactive login through the USB-serial converter, make sure the switch is on the UART1 position

Picocom can be used to connect via the serial line (assuming the USB-serial converter is USB0):

picocom -b 115200 /dev/ttyUSB0

Note

Make sure to disable software flow-control (XON/XOFF). Otherwise serial input may not be recognized.

After system bootup, the login console appears on the terminal:

rk3399-q7 login:

You can log in as root with password root or as user user with password user.

3.7. RS-232 and RS-485#

To connect via RS-232 or RS-485, connect to the RS232 / RS485 jack on HAIKOU CB-MINI-ITX.

_images/baseboard_RS232.png

Fig. 3.5 RS-232 connector#

The switch labeled RS-232 / RS-485 selects between RS-232 and RS-485 mode on the jack.

In RS-485 mode, the switch labeled Full Duplex / Half Duplex selects full- or half-duplex mode, respectively. It has no effect in RS-232 mode, which is always full-duplex.

3.8. TTL UART#

UART0 and UART1 are also available through the pin headers P12 UART0 and P30 UART1 next to the RS232 / RS485 jack. The signal level is 3.3V.

3.9. Ethernet#

PUMA SOM-RK3399-Q7 has built-in Gigabit Ethernet routed to a standard jack on HAIKOU CB-MINI-ITX.

_images/baseboard_ETH.png

Fig. 3.6 Ethernet jack#

The SD card that is shipped with the DEVKIT is configures to automatically retrieve an IP via DHCP and provides SSH login on port 22.

3.10. USB Interfaces#

PUMA SOM-RK3399-Q7 provides four USB ports:

  • 1x USB 3.0 OTG

  • 2x USB 3.0 Host

  • 1x USB 2.0 Host

_images/baseboard_usb3_otg.png

Fig. 3.7 USB 3.0 OTG port (dual-role port: can be used as a host or device interface)#

_images/baseboard_USB3.png

Fig. 3.8 USB 3.0 host ports#

_images/baseboard_USB2.png

Fig. 3.9 USB 2.0 host port#

3.10.1. Connecting an External USB Drive#

To connect a USB drive, plug it into one of the USB ports. The system should recognize the drive immediately. Check the kernel log to find the device name:

journalctl -k -10

You will be able to mount its partitions (assuming mapping to /dev/sdb1):

mkdir /mnt/usb1
mount /dev/sdb1 /mnt/usb1
ls /mnt/usb1

3.11. Video#

PUMA SOM-RK3399-Q7 supports video output on HDMI, eDP and MIPI-DSI. Some of these interfaces are muxed on the module.

_images/video_mux.svg

Fig. 3.10 PUMA SOM-RK3399-Q7 video muxing#

The BSP software will use HDMI as the default video output. Connect a display to the HDMI port and a desktop environment will be shown once booting has finished. Screen resolution will be set based on the display EDID information. Resolutions up to 3840x2160 are supported.

_images/baseboard_HDMI.png

Fig. 3.11 HDMI port#

For eDP and MIPI-DSI the Qseven LVDS pins are used which are routed to the Display connect. This expansion slot uses a PCIe connector as mechanical connection, which allows easy development of adapter boards for various different display types.

Qseven Port

Function

Alternate Function

LVDS A

MIPI-DSI

eDP

LVDS B

MIPI-DSI

MIPI-CSI
_images/baseboard_video.png

Fig. 3.12 Display connector pinout#

The kernel devicetree defines the used display configuration. Example device trees for various output configurations are provided with the BSP software package.

To configure the bootloader which devicetree to load, edit the configuration variable fdtfile in the file /boot/puma_rk3399/userEnv.txt. For example to enable DisplayPort write:

fdtfile=rk3399-puma-edp.dtb

Filename

Display 1

Display 2

rk3399-puma.dtb

HDMI

rk3399-puma-edp.dtb

Display Port on LVDS A

rk3399-puma-mipidsi.dtb

MIPI-DSI on LVDS A

rk3399-puma-hdmi+edp.dtb

HDMI

Display Port on LVDS A

rk3399-puma-hdmi+mipidsi.dtb

HDMI

MIPI-DSI on LVDS A

See https://git.embedded.cherry.de/som-hardware.git/ for video adapter reference designs.

3.12. RTC#

PUMA SOM-RK3399-Q7 contains a real-time clock (RTC) on-module. The RTC is read by the kernel on bootup and used to set the system clock.

To check the RTC value, use hwclock:

hwclock
Thu 30 Apr 2015 03:51:20 PM CEST  -0.826662 seconds

The RTC will be set automatically to the system clock on shutdown, so you can set the system clock using the date command and reboot to update the RTC:

date --set 2015-04-20
date --set 03:51:30

You can also update the RTC immediately, again with hwclock:

hwclock -v

You can set up an NTP client so the time will always be updated from the Internet. Install the client first:

apt-get install ntp

Feel free to change the /etc/ntp.conf file to use more local time sources (change servers from pool.ntp.org to use a server from your country, such as at.pool.ntp.org).

3.13. SPI, I2C and 1-Wire#

I2C, 1-wire-bus and SPI interfaces are both available on the connector labeled SPI+I2C+1-Wire.

_images/baseboard_SPI.png

Fig. 3.13 I2C and SPI header#

For I2C, there is the package i2c-tools available in Debian:

apt-get install i2c-tools

3.13.1. I2C Example - Using a Touch Keyboard#

This example uses the Atmel AT42QT2160 touch keyboard (see datasheet).

Make sure the Linux kernel driver is enable via menuconfig:

make menuconfig

Navigate to Device Drivers -> Input device support -> Keyboards and check the ATMEL AT42QT2160 Touch Sensor Chip. You must recompile the kernel and deploy it to the SD card (see Software Guide).

3.13.2. SMBus#

PUMA SOM-RK3399-Q7 provides communication through SMBus. It is basically like I2C with an additional line for interrupt and is used for connecting sensors and power peripherals.

_images/baseboard_SMBus.png

Fig. 3.14 SMBUS header#

3.13.3. Linux Bus Numbering#

Linux identifies each I2C bus using a bus number. The table below shows the mapping between Q7 names, Linux bus number and HAIKOU CB-MINI-ITX header.

Q7 name

Linux bus #

HAIKOU CB-MINI-ITX

GP0_I2C

4

SPI+I2C+1-Wire

SMB / GP1_I2C

2

SMBus

GP2_I2C / LVDS_DID

1

Display connector

LVDS_BLC

7

Display connector

The other I2C buses (as reported by i2cdetect -l) are internal to PUMA SOM-RK3399-Q7 and not routed to the Q7 connector.

3.14. GPIOs#

Eight GPIOs are provided on the pin header labeled GPIO.

The location on HAIKOU CB-MINI-ITX is displayed below:

_images/baseboard_GPIO.png

Fig. 3.15 GPIO header#

The GPIO numbers printed on the carrier board refer to numbers used in the Qseven specification. They are different than the ones used in Linux via /sys/class/gpio.

The mapping is shown in the following table:

Qseven signal

CPU pin

Linux GPIO #

GPIO0

GPIO4_D4

156

GPIO1

GPIO4_D1

153

GPIO2

GPIO4_D0

152

GPIO3

GPIO4_D5

157

GPIO4

GPIO4_D2

154

GPIO5

GPIO4_C4

148

GPIO6

GPIO4_C3

147

GPIO7

GPIO4_D3

155

To calculate the Linux GPIO # for CPU pins that are not listed in this table, use the following formula:

n = (block_number * 32) + (sub_block_number * 8) + index

Where:

  • block_number: index of the block number

  • sub_block_number: the alphabetical index of the block name, minus 1

  • index: the pin number within the block

Example:

GPIO4_D4 -> (4 * 32) + (3 * 8) + 4 = 156

To enable a GPIO, write the Linux GPIO # to the special export file:

echo 156 > /sys/class/gpio/export
ls /sys/class/gpio/gpio156
cat /sys/class/gpio/gpio156/direction
in
cat /sys/class/gpio/gpio156/value
0

To set the direction to output, write out in the GPIO’s direction file:

echo out > /sys/class/gpio/gpio156/direction
echo 1 > /sys/class/gpio/gpio156/value

The GPIO will be set to a value of 1 (high at 3.3V).

3.15. Audio#

HAIKOU CB-MINI-ITX provides two audio connectors for input and output. Line-in is on top and Headphones is on bottom of the audio connector.

_images/baseboard_audio.png

Fig. 3.16 Audio input/output port#

Additionally, an expansion connector for I2S audio is available on the bottom row of the carrier board:

_images/baseboard_I2S.png

Fig. 3.17 Connecting to the audio expansion connector#

3.16. CAN Bus#

HAIKOU CB-MINI-ITX provides a CAN connector on the bottom row.

_images/baseboard_CAN.png

Fig. 3.18 CAN header#

3.17. CTRL I/O Connector#

HAIKOU CB-MINI-ITX provides signals for watchdog trigger in- and output, SoM PMIC power-on input, reset and external display power enable.

_images/baseboard_CTRLIO.png

Fig. 3.19 CTRL I/O header#

3.18. MISC Connector#

HAIKOU CB-MINI-ITX provides signals for thermal overheat of external hardware and the processor, utility signals for SD and GPIO0.

_images/baseboard_MISC.png

Fig. 3.20 MISC header#