EC200U Main UART AT commands issue

IoT Modules LTE Standard Module
1

Hi all,
I´m using a Quectel EV QuecPython Board EC200U/A-XX with the chipset EC200U-EU. There I have installed the FW EC200UEUAAR03A17M08 with configuration version 01.200.01.200. When I´m using the eval boarod connect it with USB-C to a Windows PC I can connect with QCOM Tool and sending AT commands when I´m opening the AT COM port.

Now I´m trying to connect the eval board to an embedded board for AT communication. I´m supplying the quectel eval board with 5V(J8-1), GND (J8-3), J8-4 (UART2_TX_3V3), J8-5(UART2_RX_3V3) RX/TX is connected to a UART port RX=TX and TX=RX. My embedded module uses 3.3V as level and as I can see from the naming as well as the schematic the UART2_RX/TX are also using level 3.3V with a level shifter.

When I´m opening my COM port with the following command:
“microcom -s 115200 /dev/ttymxc4” and sending AT commands I only see an output, if I´m sending the following AT command “ATE1” at the end. I used the COM port with another GSM Module which worked absolutely fine. Do you have any idea what I´m missing?

Here the output from my terminal program:

# echo -e "AT\r" > /dev/ttymxc4
#
# echo -e "AT+CFUN?\r" > /dev/ttymxc4
# echo -e "ATE1\r" > /dev/ttymxc4
# AT


OK

AT+CFUN?


+CFUN: 1



OK

ATE1


OK


#
2

Hi ，
Before sending the AT command, you need to execute ATE1 first, which may solve your problem.

3

Thanks for your hint but this doesn´t solve my issue. I´ve done several tests (see below). All tests are performed after a cold start. Only the kernel initialized this port, nothing else requests the UART port at runtime, except my manual commands.

First test scenario:

#
# cat /dev/ttymxc4 &
# echo -e "ATE1\r" > /dev/ttymxc4
# echo -e "AT\r" > /dev/ttymxc4
# echo -e "AT+CPIN?\r" > /dev/ttymxc4
# echo -e "AT+CMGF?\r" > /dev/ttymxc4
# echo -e "ATE1\r" > /dev/ttymxc4
#

nothing happened for first test scenario.

# stty -F /dev/ttymxc4 115200 cs8 -parenb -cstopb -ixon -echo
# cat /dev/ttymxc4 &
# echo -e "ATE1\r" > /dev/ttymxc4
# ATE1


OK


# echo -e "AT\r" > /dev/ttymxc4
# echo -e "AT+CPIN?\r" > /dev/ttymxc4
# echo -e "AT+CMGF?\r" > /dev/ttymxc4
# echo -e "ATE1\r" > /dev/ttymxc4
# AT


OK

AT+CPIN?


+CME ERROR: 10

AT+CMGF?


+CMGF: 1



OK

ATE1


OK


#

Second test scenario. I only see an output if I send the command “ATE1”, even if send “ATE1” at the beginning.

# stty -F /dev/ttymxc4 115200 cs8 -parenb -cstopb -ixon -ixoff -crtscts -echo
# cat /dev/ttymxc4 &
# echo -e "ATE1\r" > /dev/ttymxc4
# ATE1


OK


# echo -e "AT\r" > /dev/ttymxc4
# echo -e "AT+CPIN?\r" > /dev/ttymxc4
# echo -e "AT+CMGF?\r" > /dev/ttymxc4
# echo -e "ATE1\r" > /dev/ttymxc4
# AT


OK

AT+CPIN?


+CME ERROR: 10

AT+CMGF?


+CMGF: 1



OK

ATE1


OK


#

Third test scenario. Again I only see an output, when I´m sending the command “ATE1”.

Do you have any idea why this happens? Do I use some wrong FW version? Do I missed something for the HW connection? Do I need to configure something specific?

best regards