Interface Definition

Overall Interface Definition

The LBA3588S offers a rich set of interfaces, detailed as follows:

../../_images/interface.png

Silkscreen	Device Node	Remarks
USB1		Type-A USB3.0 host
USB2		Type-A USB3.0 host
USB3		Type-A USB3.0 host
PWR LED		Power indicator light
4G LED		4G light 4G/5G Dialing
SYS LED	work1	System light
STA LED	work2	STA light
RS485	/dev/ttyS9	Serial port, default baud rate 9600
UART1	/dev/ttyS4	Serial port, default baud rate 9600
UART2	/dev/ttyS6	Serial port, default baud rate 9600
RS232_1	/dev/ttysWK0
RS232_2	/dev/ttysWK1
RS232_3	/dev/ttysWK2
RS232_4	/dev/ttysWK3
HDMI1	card0-HDMI-A-1	HDMI output, supports up to 4K@60fps
Type-C		Can switch USB and DP signals
MIC		Input sound, record audio files
LINE		Play audio files
ETH0	eth0	Gigabit network card
WIFI	wlan0	2.4/5GHz

UART Usage

The serial port is a common communication interface used for serial communication with external devices. The LBA3588S provides multiple serial ports, each corresponding to different device nodes. Before using the serial port, ensure that the port is correctly connected and the baud rate and other parameters are set consistently.

The RS485 device file is /dev/ttyS9. Run the following command on the development board device:

Send a string to the host:

echo "neardi RS485 test..." > /dev/ttyS9

The host’s serial terminal will receive the string “neardi RS485 test…”. The development board receives data:

Receive a string sent by the host:

cat /dev/ttyS0

Similarly, the device files for UART1 and UART2 are /dev/ttyS4 and /dev/ttyS6.

RS232 Usage

The usage method for RS232 is similar to RS485, UART1, and UART2; just replace the device file accordingly.

HDMI/DP Explanation

The xrandx command can be used to check the current HDMI connection:

neardi@3588:~$ xrandr 
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
HDMI-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1920x1080     60.00*+  60.00    50.00    30.00    24.00  
   4096x2160     24.00  
   3840x2160     30.00    25.00    24.00  
   1920x1080i    60.00    50.00  
   1280x720      60.00    60.00    50.00    50.00    30.00    24.00  
   720x576       50.00    50.00  
   720x480       59.94    59.94    59.94  
DP-1 disconnected (normal left inverted right x axis y axis)

Complete Node Definitions:

HDMI1：/sys/devices/platform/display-subsystem/drm/card0/card0-HDMI-A-1/
DP：/sys/devices/platform/display-subsystem/drm/card0/card0-DP-2/

ETH Explanation

You can check the IP address via the debug serial port, ssh, or adb, for example:

neardi@3588:~$ ifconfig -a
enP2p33s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.65  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::7df7:e74d:497e:345d  prefixlen 64  scopeid 0x20<link>
        ether 62:ea:fb:ca:95:e7  txqueuelen 1000  (Ethernet)
        RX packets 2548  bytes 210938 (210.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 338  bytes 46899 (46.8 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 140  base 0xd000  

Wi-Fi Explanation

Check the current Wi-Fi model with the following commands:

cat /sys/bus/sdio/devices/mmc2\:0001\:1/vendor
cat /sys/bus/sdio/devices/mmc2\:0001\:1/device 

0x02d00xaae8 is AP6275S，0x024c0xb852 is RTL8852

Starting Hotspot

LED Explanation

Complete nodes:

SYS LED：cat /sys/devices/platform/leds/leds/work1/brightness
STA LED：cat /sys/devices/platform/leds/leds/work2/brightness

MIC Usage

Use the following command to record audio files, supporting formats such as wav, mp3, etc.

Record dual-channel 16-bit little-endian audio at a sampling rate of 48000Hz, then save it as a 001.wav file.

arecord  -Dhw:0,0 -r48000 -f S16_LE -c2 > 001.wav

• -Dhw:0,0 specifies the recording device, 0,0 is card 0 device 0, which is the first sound card’s first device.

• -r48000 specifies the sampling rate in Hz, 48000 means 48000 samples per second.

• -f S16_LE specifies the sample format, S16_LE means signed 16-bit little-endian format, each sample point occupies 2 bytes, with the low byte first and the high byte last.

• -c2 specifies the number of channels, 2 means stereo.

• > 001.wav specifies the output file, > redirects standard output to a file, 001.wav is the file name, wav is the file format.

LINE Usage

Use the first sound card’s first device to play the 001.wav file.

aplay -D hw:0,0 001.wav

• -D hw:0,0 specifies the playback device, hw:0,0 is card 0 device 0, which is the first sound card’s first device.

• 001.wav specifies the audio file, wav is the file format, 001 is the file name.