Introduction of the development board hardware

*The firmware used in the following introduction is the D1 Nezha Development Board v0.5 release firmware, and the JD9366AB LCD screen driver is selected in the kernel.

*Firmware download address：D1 Nezha development board test firmware 20210416

*See：D1 Nezha Development Board Schematic 20210520

Connection Diagram

The D1-Nezha development board is like a Swiss Army knife that can be connected to many external devices.

USB

The board has a USB HOST and two Type-C USB ports, of which.

（1）the one next to HDMI can only be used for power supply with an input voltage/current of 5V/2A.

（2）The USB Type-C next to the serial line is used for data transfer and can be used for firmware burning, device information burning, ADB shell, adb push/pull, etc. It can also supply power. The power supply size mainly depends on the current output of the PC USB port, which can generally meet the system startup requirements, but some functions may be underpowered, such as MIPI-DSI screens, etc., need to be plugged into 5V/2A in order to provide a stable power supply.

（3）USB HOST can be used to insert U disk, USB camera, mouse, keyboard, etc., following the standard USB 2.0 protocol.

Serial ports

UART port on the development board has three pins, GND, RX, TX, each pin is printed on the development board corresponding to the function

The official CH340 serial cable sequence is: black-GND, green-RX, white-TX, red for power supply, no need to plug here, the specific connection is as follows:

Windows PC needs to install the serial to USB driver when using the serial cable

PC will recognize the serial chip model when inserted into the serial port, the development kit comes with a serial chip model FT232R or CH341SER (internal test developer version)

Serial port driver download can refer to：

https://www.aw-ol.com/downloads?cat=5

You can also search for your own serial driver or use your own serial cable; we recommend using a 3.3V serial cable.

Baud rate：115200

Display Interface

The display interface can be connected to the MIPI-DSI screen and touch, the line sequence is as follows: The development board comes with the firmware default display interface output, if the non-display interface output, or has been changed to HDMI output, you can use the following command to switch to the display interface output.

cd /sys/kernel/debug/dispdbg
echo disp0 > name; echo switch1 > command; echo 1 4 0 0 0x4 0x101 0 0 0 8 > param; echo 1 > start;

echo 1 4 0 0 0x4 0x101 0 0 0 8 > param;——The first parameter 1 here represents the MIPI-DSI output, if it is to be switched to HDMI output, then change to 4.

Using the default firmware, the Tina Linux penguin small logo will be displayed at startup

Show colorbar

echo 1 > /sys/class/disp/disp/attr/colorbar

Play local video

tplayerdemo /usr/lib/tt-data/01-1080P-HEVC-AAC-60F.mkv

HDMI

Switch to HDMI output.

cd /sys/kernel/debug/dispdbg
echo disp0 > name; echo switch1 > command; echo 4 10 0 0 0x4 0x101 0 0 0 8 > param; echo 1 > start;

Test displaying colorbar.

echo 1 > /sys/class/disp/disp/attr/colorbar

Test playing video：

tplayerdemo /usr/lib/tt-data/01-1080P-HEVC-AAC-60F.mkv

Microphone daughter board

The microphone daughterboard is connected as shown in the figure：

The recording command is as follows：

// use arecord command to record a sample rate of 16000, format S16_LE, 6-channel audio file on the device hardware device snddmic, save to /tmp/test.wav

arecord -D hw:snddmic -r 16000 -f S16_LE -c 6 /tmp/test.wav

Using adb pull adb pull to pull the audio file to the PC with audio processing software Audacity to open, you can see the recorded six channels of sound as follows: microphone daughterboard cable sequence as follows.：

3.5mm headphone port

As shown in the diagram, plug in headphones or other 3.5mm audio devices to play the audio with the following commands.

aplay /usr/lib/tt-data/16000-mono-s16_le.wav

*D1 Nezha development board support 3.5mm interface for the American Standard (CTIA), that is, from the inside to the outside of the left, right, ground, Mic, respectively, the current mainstream cell phone headset interface is the American Standard.

SD card

The SD card slot is located on the back of the board, and the SD card can be inserted to read data from the SD card. The data of the SD card will be automatically hung in the /mnt/SDCARD directory. cd /mnt/SDCARD can be attached to the file under the SD card: