AT uart

[dave]

I am trying to set up the AT library to directly talk to the modem through a uart on the nrf9160DK.  But when I enter the commands to test "AT+CFUN?" I just get it echoed back

I have a USB to UART converter connected to P0.00 and P0.01 to talk to the modem.

prj.conf

#Enable logger module
CONFIG_LOG=y

#Enable logging through UART
CONFIG_SERIAL=y
CONFIG_SHELL_LOG_BACKEND=y

#Enable shell
CONFIG_SHELL=y

CONFIG_AT_HOST_LIBRARY=y
CONFIG_AT_HOST_UART_INIT_TIMEOUT=10000
CONFIG_AT_HOST_CMD_MAX_LEN=32

Device overlay

&interface_to_nrf52840 {
    gpio-map = <0 0 &gpio0 17 0>,
               <1 0 &gpio0 18 0>,
               <2 0 &gpio0 19 0>,
               <3 0 &gpio0 21 0>,
               <4 0 &gpio0 22 0>,
               <5 0 &gpio0 23 0>,
               <9 0 &gpio0 24 0>;
};

&uart1 {
    status = "okay";
};

&uart0 {
    status = "okay";
};

/ {
    chosen {
        zephyr,console = &uart0;
    };
};

/ {
    chosen {
        zephyr,shell-uart = &uart0;
    };
};

&uart1_default {
    group2 {
        psels = <NRF_PSEL(UART_RX, 0, 0)>;
    };
};

&uart1_default {
    group1 {
        psels = <NRF_PSEL(UART_TX, 0, 1)>;
    };
};

&uart1 {
    hw-flow-control;
};

&uart1 {
    /delete-property/ hw-flow-control;
};

&uart0_default {
    group2 {
        psels = <NRF_PSEL(UART_RX, 0, 16)>, <NRF_PSEL(UART_CTS, 0, 26)>;
    };
};

&uart0_default {
    group1 {
        psels = <NRF_PSEL(UART_TX, 0, 17)>, <NRF_PSEL(UART_RTS, 0, 27)>;
    };
};

[mark.blackburn.orpyx]

You don't need to connect USB to UART convertor to any pins. The DK already has VCOM ports over the USB connection.

I recommend trying the at_client sample.

In VS Code "Create a new application"

"Copy a sample"

Start typing "at_client" and select at_client Sample

Create a build configuration for nrf9160 dk and don't make any changes to the device tree configuration. The DK has 3 UARTs. Two of them are for the nRF9160. Try connecting to all of them at 115200, and keep type AT<ENTER> util one of them responds with "OK"

[dave]

I tried building the AT_client sample but it was giving build errors.  I'll try again

But either way, I need to use regular GPIO pins for the uart since that is what I'll use in production and not a virtual com port over the USB

[mark.blackburn.orpyx]

I think you are running into a contention because the IC there a a MCU that is driving the VCOM lines on the DK. I think you should change which pins you are using for your UART on pins P0.00 and P0.01 if you want to use the Arduino connectors.

[mark.blackburn.orpyx]

I think P0.16 and P0.17 would be safe to use. They are on the nRF52 interface, but those should not be driven if the default firmware on that chip is left as is or erased.

[dejans]

Hi,

Information about GPIO pins on the nRF9160-dk hardware can be found in the documentation.

dave said:

I tried building the AT_client sample but it was giving build errors.  I'll try again

If you still experience an issue, please provide your build log.

Best regards,
Dejan

[dave]

Right now I have uart0 set up for P0.016/P0.17 which should be for the AT uart, and then uart 1 set up with P0.00/P0.01 for logging / shell.

If I don't have the AT host library enabled the shell and logging works ok.. but if I enable the AT host library, neither works.

[dejans]

Hi,

AT Host library uses UART0 by default but this can be changed using ncs,at-host-uart choice in devicetree.
Regarding the pins, there is likely pin conflict in your configuration, i.e. pins are not chosen correctly. You can check GPIO pin usage in the default pin settings table in the chapter 4.6 (GPIO interfaces) of the nRF9160-dk hardware user guide.
You could try to use pins for buttons or leds which are routed to the pin header. 
You should also use your own pinctrl instances instead of matching ones already set up in the board. For example,

&pinctrl {
   my_pin_configuration: my_pin_configuration {
      group1 {
         psels = <NRF_PSEL(UART_TX, 0, 14)>,
                 <NRF_PSEL(UART_RX, 0, 16)>;
      };
   };
};

and 

&uart0 {
  pinctrl-0 = <&my_pin_configuration>;
  pinctrl-names = "default";
};

Best regards,
Dejan

[dave]

With respect to pin ctrl, are you saying that the current way I have them defined in the overlay file is not recommended?

[dejans]

Hi,

I am not sure if this answers your question, but the Note in Pin configuration discourages adding pin configuration defaults in pre-defined nodes.

Best regards,
Dejan