[SOLVED] UART as /dev/ttyS4 not available - Please help!

KahrenAKahrenA New Member Posts: 10
edited October 9 in UP Board Linux

On Ubuntu 16.04 , Here's what I get

sudo setserial -g /dev/ttyS[0123456789]
/dev/ttyS0, UART: unknown, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: unknown, Port: 0x02f8, IRQ: 3
/dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4
/dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3 ---- S4 & S5 missing
/dev/ttyS6, UART: unknown, Port: 0x0000, IRQ: 0
/dev/ttyS7, UART: unknown, Port: 0x0000, IRQ: 0
/dev/ttyS8, UART: unknown, Port: 0x0000, IRQ: 0
/dev/ttyS9, UART: unknown, Port: 0x0000, IRQ: 0

=======================================================
[email protected]:~/kampr-face-access-control$ dmesg | grep tty
[ 0.000000] console [tty0] enabled
[ 5.261289] dw-apb-uart.8: ttyS4 at MMIO 0x91524000 (irq = 4, base_baud = 115200) is a 16550A
[ 5.261475] serial serial0: tty port ttyS4 registered
[ 5.280603] dw-apb-uart.9: ttyS5 at MMIO 0x91522000 (irq = 5, base_baud = 115200) is a 16550A
[ 5.280833] serial serial1: tty port ttyS5 registered

=====================================================
yet when I do
import serial

ComPort = serial.Serial('/dev/ttyS4')

ComPort.baudrate = 115200
ComPort.bytesize = 8
ComPort.parity = 'N'
ComPort.stopbits = 1
data = ComPort.readline()
print("data : {}".format(data) )
ComPort.close()

I get --- FileNotFoundError: [Errno 2] No such file or directory: '/dev/ttyS4'

I really would appreciate guidance here! One thing to note, when I installed ubuntu 16.04.6 the instructions indicated to replace generic kernel but the listed command failed ... is the kernel the issue here?
Thanks,
Kahren

Comments

  • KahrenAKahrenA New Member Posts: 10

    the issue was with the kernel .. fixed it and now /dev /ttyS4 is visible... at this point I don't get any data with CTS pulled to GND and the following code running on the UpBoard,, Note from my laptop I write bytearray(b'X') to USB to RS485 ... on the UpBoard side there is RS485 <--> TTL adapter that has TxD and RxD on the TTL side to UpBoard ... No other signals like RTS, CTS ... I see the TxD LED come on on the laptop side's adapter, I see the RxD LED on the UpBoard side adapter BUT my program below is waiting for dataAvailable... I am using pin 8 Tx and pin 10 Rx, pin 1 or 2 for Vcc and pin 6 GND .... any help would be appreciated!!!

    import mraa
    import sys
    import time

    class RS485(object) :
    """
    TODO
    """
    #define UART parameters
    BAUD_RATE = 9600 #115200
    BYTE_SIZE = 8
    PARITY = 'N'
    STOP_BITS = 1
    RTSCTS = False #True
    XONXOFF = False
    BREAK_DURATION = 30 # Check OSDP spec

    def __init__(self):
        """
        TODO
        """   
        print("mraa version : {}".format(mraa.getVersion()) )
    
        mraa.init()
    
        print("In UART init")
        # initialise UART 
        self.uart = mraa.Uart("/dev/ttyS4")
        print ("/dev/ttyS4 Uart initialized")
    
        device_path = self.uart.getDevicePath()
        print("device path is : {}".format(device_path) )
    
        # Set UART parameters
        self.uart.setBaudRate(RS485.BAUD_RATE)
        print("baudrate set") 
    
        self.uart.setMode(RS485.BYTE_SIZE, mraa.UART_PARITY_NONE, RS485.STOP_BITS)
        print("setmode complete")
    
        self.uart.setFlowcontrol(RS485.XONXOFF, RS485.RTSCTS)
        print("setFlowControl complete")
    
        print("done with UART class instantiation")
    

    def main():
    """
    Entry point of program
    """
    rs485 = RS485()
    print("returned from init")

    # Start a neverending loop waiting for data to arrive.
    # Press Ctrl+C to get out of it.
    while True:
    
        data_ready = rs485.uart.dataAvailable()
        print ("data_ready = {}".format(data_ready) )
        if data_ready:
            # We are doing 1-byte reads here
            data_byte = rs485.uart.readStr(1)
            print(data_byte)
    
            # Just a two-way half-duplex communication example, "X" is a flag
            if data_byte == "X":
                rs485.uart.writeStr("Yes, master!")
    

    # else:
    # rs485.uart.writeStr("Hi!")

        time.sleep(0.5)
    

    if name == "main":
    sys.exit(main())

  • KahrenAKahrenA New Member Posts: 10

    Taking the idea from another thread, I isolated everything except the UART, connected UART_tx and UART-Rx pins 6 & 8 and ran sudo echo "hello world" /dev/ttyS4 and from another terminal ran sudo cat -v /dev/ttyS4 and nothing is received ... Does this mean my UART is bad?

  • ccaldeccalde admin Administrator, Moderator, Emutex Posts: 348 admin

    Hi @KahrenA ,

    Could you please confirm the BIOS version and the kernel version?
    1. uname -a
    2. cat /etc/*release
    3. dmesg | grep BIOS

  • KahrenAKahrenA New Member Posts: 10

    thank you for your quick response... below are what you asked for ...
    uname -a
    Linux kahren-UP-APL01 4.15.0-37-generic #40~upboard03-Ubuntu SMP Wed Dec 12 16:21:24 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

    cat /etc/*release
    DISTRIB_ID=Ubuntu
    DISTRIB_RELEASE=16.04
    DISTRIB_CODENAME=xenial
    DISTRIB_DESCRIPTION="Ubuntu 16.04.6 LTS"
    NAME="Ubuntu"
    VERSION="16.04.6 LTS (Xenial Xerus)"
    ID=ubuntu
    ID_LIKE=debian
    PRETTY_NAME="Ubuntu 16.04.6 LTS"
    VERSION_ID="16.04"
    HOME_URL="http://www.ubuntu.com/"
    SUPPORT_URL="http://help.ubuntu.com/"
    BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
    VERSION_CODENAME=xenial
    UBUNTU_CODENAME=xenial

    dmesg | grep BIOS
    [ 0.000000] e820: BIOS-provided physical RAM map:
    [ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000003efff] usable
    [ 0.000000] BIOS-e820: [mem 0x000000000003f000-0x000000000003ffff] reserved
    [ 0.000000] BIOS-e820: [mem 0x0000000000040000-0x000000000009dfff] usable
    [ 0.000000] BIOS-e820: [mem 0x000000000009e000-0x00000000000fffff] reserved
    [ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000000fffffff] usable
    [ 0.000000] BIOS-e820: [mem 0x0000000010000000-0x0000000012150fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x0000000012151000-0x0000000077b38fff] usable
    [ 0.000000] BIOS-e820: [mem 0x0000000077b39000-0x0000000079c56fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x0000000079c57000-0x0000000079c6bfff] ACPI data
    [ 0.000000] BIOS-e820: [mem 0x0000000079c6c000-0x0000000079ccbfff] ACPI NVS
    [ 0.000000] BIOS-e820: [mem 0x0000000079ccc000-0x000000007a024fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x000000007a025000-0x000000007a070fff] type 20
    [ 0.000000] BIOS-e820: [mem 0x000000007a071000-0x000000007a3defff] usable
    [ 0.000000] BIOS-e820: [mem 0x000000007a3df000-0x000000007a3dffff] ACPI NVS
    [ 0.000000] BIOS-e820: [mem 0x000000007a3e0000-0x000000007a409fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x000000007a40a000-0x000000007a964fff] usable
    [ 0.000000] BIOS-e820: [mem 0x000000007a965000-0x000000007a966fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x000000007a967000-0x000000007affffff] usable
    [ 0.000000] BIOS-e820: [mem 0x000000007b000000-0x000000007fffffff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000d0000000-0x00000000d0ffffff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000e0000000-0x00000000efffffff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000fe042000-0x00000000fe044fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000fe900000-0x00000000fe902fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000fed01000-0x00000000fed01fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
    [ 0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
    [ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000017fffffff] usable
    [ 0.000000] efi: ACPI=0x79c5e000 ACPI 2.0=0x79c5e000 SMBIOS=0x79edd000 SMBIOS 3.0=0x79edc000
    [ 0.000000] SMBIOS 3.0.0 present.
    [ 0.000000] DMI: AAEON UP-APL01/UP-APL01, BIOS UPA1AM21 09/01/2017
    [ 0.000000] Calgary: detecting Calgary via BIOS EBDA area
    [ 2.504180] intel_idle: Please enable MWAIT in BIOS SETUP
    [ 2.600392] BIOS EDD facility v0.16 2004-Jun-25, 0 devices found
    [email protected]:~$

  • KahrenAKahrenA New Member Posts: 10

    any obvious issue? should i upgrade my bios? if so to 4.0 or 4.6?

  • KahrenAKahrenA New Member Posts: 10

    SOLVED!! turns out to be a silly thing.. I need to use ttyS5 and not ttyS4 ... the wiki community pint out page says otherwise... WHY?
    http://wiki.up-community.org/Pinout#UART_Example_.231

  • ccaldeccalde admin Administrator, Moderator, Emutex Posts: 348 admin

    Hi @KahrenA ,

    Thank you for the contribution.
    We will check it and redefine the UP Wiki example.

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