UART HAT Question & Answer


1. Auto load UART Setting

check crontab setting is correct or not?


 command   ->  sudo crontab -e

 example for 4 UART port    0x4C , 0x4D

Auto Load Pi8s when Pi Boot


sudo crontab e


add 4 line in the end of file


@reboot /usr/bin/./Pi8s a 0x4C c 1 b 38400 s 1

@reboot /usr/bin/./Pi8s a 0x4C c 2 b 38400 s 2

@reboot /usr/bin/./Pi8s a 0x4D c 1 b 38400 s 3

@reboot /usr/bin/./Pi8s a 0x4D c 2 b 38400 s 4


when load minicom also open port1 (picom1 /dev/pts/x)

minicom D $(cat /dev/picom1)


(2) Use our  check system available UART status                  can help you know the UART port status



(3) in terminal mode type "top"  to check how many UART port in system


if you have 2 UART product you should see 2 Pi8s run in system


if you have 4 UART product you should see 4 Pi8s run in system


(4)  increase i2c bus speed to prevent  data lost

 Check your i2c bus speed setting in /boot/config.txt

add a line in end of file




   suggest use Raspbian Image   raspbian-2017-04-10

   old image can download   Here



(5) Command mode for UART HAT

Also provided is a terminal command mode to activate serial ports through a terminal / ssh.
You can also activate a serial port on boot up with the provided software.
Commands for starting the serial ports via command line;
ADDR = Address of Serial Port e.g. 0x48, 0x49, 0x4C, and 0x4D
CHANNEL = Channel of serial Port ( 1 / 2 )
BAUD = Baud Rate for the Serial Port
DEVPTS = PICOM Service Number ( Will direct the filename to /dev/picomX where X = your number )

For example, To start a serial port from 0x49, on channel 2 with 115200 Baud run the following;
./Pi8s -a 0x49 -c 2 -b 115200 -s 1
This will activate the serial port and then set /dev/picom1 to your serial port location /dev/pts/X




    1. device ->   /dev/pts/1        2 . Baud rate  38400

    3. click Open device  

    4. input AT command (HC-05 blutetooth module)

    5. screen will show Bluetooth module response



  (6) PiCOM 1~4  and /dev/pts/x

    Q: M y Serial software keeps telling me /dev/picom1 isn't a serial port:
     A:  /dev/picomX isn't a serial port, its a file that stores the location
     of the serial port as a link. such as


   use can help you know the status PiCOM 1~4 and /dev/pts/x 



When you click "Open device" the message screen display information about /pts/x  only, can't open  /dev/picom 1~ 4 ,  the /dev/picom1 ~4 is not a real com port


(7) PiCOM 1~4  and /dev/pts/x loop test

Port 2  Tx  to Port 1  Rx

Port 1  Tx  to Port 2  Rx

Port 4  Tx  to Port 3  Rx

Port 3  Tx  to Port 4  Rx

(8) Pi Raspbian stretch image install new ver cutecom

new Version Cutecom input  /dev/pts/x

login as user pi ,

edit file   /home/pi/.config/Cutecom/Cutecom5.conf

save after edit, then click "cutocom "






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