How to use socket?

[Yusuke]

<Environment>
- Windows10
- nrf v1.3.0
- modem fw 1.2.0

I'm attempting to make a socket and communicate with the modem using it.

However, sending data doesn't work out. It was working in v1.2.0. Any tip?

I don't want to use at_cmd.c becuase I need a exclusive  socket for SMS notification.

<main.c>

#include <zephyr.h>
#include <stdio.h>
#include <net/socket.h>
#include <modem/lte_lc.h>

#define BUF_LEN 128

int fd;

void main(){
    int ret;
    char at_cmd[] = "AT\n";
    char buf[BUF_LEN];
    
	/* Configure LTE-M */
    printk("LTE Link Connecting ...\n");
    ret = lte_lc_init_and_connect();
    printk("LTE Link Connected!\n");
	if (ret) {
		printk("Error: modem_configure\n");
		return;
	}

	/* SMS socket set up*/
	fd = socket(AF_LTE, 0, NPROTO_AT); /* init fd */
	if (fd == -1) {
		return;
	}

	// Send AT command => ERROR !!
	if (send(fd, at_cmd, strlen(at_cmd), 0) <= 0) {
        printk("Error: send\n");
        return;
    }

	// blocking receive
	if (recv(fd, buf, BUF_LEN, MSG_DONTWAIT) <= 0) {
        printk("Error: send\n");
        return;
    }

    printk("Socket works out!\n");
    
    return;
}

[Martin Lesund]

Hi Yusuke,
Please start out just by running AT Client sample and verify that you actually can send SMS with AT commands and that you have a SIM card that supports this.

You can see an example in this thread on how to do it:
https://devzone.nordicsemi.com/f/nordic-q-a/41755/sending-sms-using-at_client-example/164297#164297

[Yusuke]

in v1.2.0, I could receive SMS.

I'll check the link later

[Yusuke]

I read the link but it doesn't explain how to use sms.h library. 

[Yusuke]

in sms.h

/**
 * @brief Register a new listener.
 *
 * A listener is identified by a unique handle value. This handle should be used
 * to unregister the listener. A listener can be registered multiple times with
 * the same or a different context.
 *
 * @param listener Callback function. Cannot be null.
 * @param context User context. Can be null if not used.
 *
 * @retval -EINVAL Invalid parameter.
 * @retval -ENOMEM No memory to register new observers.
 * @return Handle identifying the listener,
 *         or a negative value if an error occurred.
 */
int sms_register_listener(sms_callback_t listener, void *context);

*The handle should be used to unregister the listener

=> what does this mean?

I would like to keep registering SMS notification. In this case, do you have to unregister it every time the handler is called?

[Yusuke]

I read the link, but the code doesn't work. Instead this works out

int fd = nrf_socket(NRF_AF_LTE, NRF_SOCK_DGRAM, NRF_PROTO_AT);

On the other hand, this doesn't work. confusing. I referred to at_cmd.c

int fd = socket(AF_LTE, SOCK_DGRAM, NPROTO_AT);

[Yusuke]

OK. I cloud receive SMS using nrf_socket. Instead, sms.c doesn't work. I may use it in a wrong way. I hope sample program will be provided.