uart issue in pi-3

Question

I have a problem regarding the uart not working at all, following are the steps as done from my side.

updated and upgraded the raspberry pi,initially i installed raspbian wheezy to sd card and i am running pi over ssh.

in config.txt added

enable_uart=1
core_freq=250
force_turbo=1
dtoverlay=pi3-disable-bt

in cmdline.txt removed the line related to ttyAMA0, the remaining command is as follows:

dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p rootfstype=ext4 elevator=deadline rootwait

i opened the minicom and tried to see if data appears, but i was not able to visualise any kind of data. Following is the python code:

import time
import serial
print "Starting program"
ser = serial.Serial('/dev/ttyAMA0', baudrate=9600,
                    parity=serial.PARITY_NONE,
                    stopbits=serial.STOPBITS_ONE,
                    bytesize=serial.EIGHTBITS
                    )
time.sleep(1)
while 1:
    ser.write('Success')
    print 'Data Echo Mode Enabled'
    ser.close()

Why wheezy? The better choice is the current jessie unless you actually need wheezy. You appear to be following old instructions re the serial link in the Pi3. — joan, Apr 20 '17 at 12:40
@fusseldieb : Sorry, but i am new to raspberry pi so i exactly dnt have idea how to use /dev/ttyS0 — Dipesh Sharma, Apr 20 '17 at 12:48
@DipeshSharma Just delete the "/dev/ttyAMA0" and write "/dev/ttyS0". Simple as that... — Fusseldieb, Apr 20 '17 at 12:50
@Fusseldieb If Dipesh is using the `pi3-disable-bt` overlay then `ttyAMA0` is fine. — goldilocks, Apr 20 '17 at 12:53
and when i run sudo systemctl disable hciuart to stop running bluetooth i am getting "system command not found" — Dipesh Sharma, Apr 20 '17 at 12:55
@fusseldieb:- Thanks the /dev/ttyS0 solved the issue, but one thing i didnt understand i am able to see data on hercules(virtual terminal for usb to ttl ) but i was not able to visualise data on minicom — Dipesh Sharma, Apr 20 '17 at 13:21
@DipeshSharma Even using "ttyS0"? Maybe wrong baudrate, stopbit, etc...? Or even switched TX RX pins... Or wrong TTL voltage (Unlikely, but not impossible) — Fusseldieb, Apr 20 '17 at 13:24
@DipeshSharma `sudo systemctl disable hciuart` will only work on Jessie. If you're using Wheezy, do something like `sudo update-rc.d hciuart disable`. — Hydraxan14, Apr 20 '17 at 16:37
Might need to use `sudo minicom` in order to read from `/dev/ttyS0`. — Hydraxan14, Apr 20 '17 at 16:41
@Fusseldieb,: The issue regarding the uart is solved. Thanks a lot guys for the support. The issue was with wire jumper connecting. Now i am able to see the data on minicom too. — Dipesh Sharma, Apr 21 '17 at 09:21

score 1 · Answer 1 · answered Apr 13 '18 at 02:58

As detailed in the comments, the solution is to replace "/dev/ttyAMA0" with "/dev/ttyS0" in the code, giving:

import time
import serial
print "Starting program"
ser = serial.Serial('/dev/ttyS0', baudrate=9600,
                    parity=serial.PARITY_NONE,
                    stopbits=serial.STOPBITS_ONE,
                    bytesize=serial.EIGHTBITS
                    )
time.sleep(1)
while 1:
    ser.write('Success')
    print 'Data Echo Mode Enabled'
    ser.close()

uart issue in pi-3

1 Answers1