How to handle at command in nRF9160?

[Yusuke]

I want to handle at command in main.c file. How can you do it?

For example, how can you send "AT+COPS?" and received return value?

I tested simple_at program below, but it doesn't work.

https://github.com/Rallare/fw-nrfconnect-nrf/tree/nrf9160_samples/samples/nrf9160/simple_at

Peripheral              Domain          Status
00 NRF_P0               Non-Secure      OK
01 NRF_CLOCK            Non-Secure      OK
02 NRF_RTC1             Non-Secure      OK
03 NRF_NVMC             Non-Secure      OK
04 NRF_UARTE1           Non-Secure      OK
05 NRF_UARTE2           Secure          SKIP
06 NRF_IPC              Non-Secure      OK
07 NRF_VMC              Non-Secure      OK
08 NRF_FPU              Non-Secure      OK
09 NRF_EGU1             Non-Secure      OK
10 NRF_EGU2             Non-Secure      OK
11 NRF_TWIM2            Non-Secure      OK
12 NRF_SPIM3            Non-Secure      OK
13 NRF_TIMER0           Non-Secure      OK
14 NRF_TIMER1           Non-Secure      OK
15 NRF_TIMER2           Non-Secure      OK
16 NRF_SAADC            Non-Secure      OK
17 NRF_GPIOTE1          Non-Secure      OK

SPM: NS image at 0x8000
SPM: NS MSP at 0x20022610
SPM: NS reset vector at 0x9efd
SPM: prepare to jump to Non-Secure image.
Exception occurred in Secure State
***** HARD FAULT *****
  Fault escalation (see below)
***** BUS FAULT *****
  Precise data bus error
  BFAR Address: 0x50008120
***** Hardware exception *****
Current thread ID = 0x20020130
Faulting instruction address = 0x0
Fatal fault in ISR! Spinning...

Thanks

[Øyvind]

Hello, 

Please have a look at the AT Client sample project. This allows you to send and receive AT commands in a terminal e.g. LTE Link Monitor.

Kind regards,
Øyvind

[Yusuke]

Thank you for your reply.

I've already checked the at client sample.

github.com/.../at_client

I don't see code to send at command in main.c. 

Can u tell me which lines send at command?

[Øyvind]

Sorry, I misread your initial question. I thought you just needed a way to send and receive AT commands.

The AT_client sample uses threads in Zephyr OS to handle AT commands. 

I tested simple_at program below, but it doesn't work.

To solve the hard fault issue, please try to add the following in the prj.conf file:

CONFIG_MAIN_STACK_SIZE=4096

 

Thanks!

Kind regards,
Øyvind

[Yusuke]

Thanks so much! It works out!

Can I ask one more question?

I want to send MNC and MNN data of LTE cell station through MQTT so that I'm trying to integrate mqtt_simple and simple_at programs.
https://github.com/NordicPlayground/fw-nrfconnect-nrf/tree/master/samples/nrf9160/mqtt_simple
https://github.com/Rallare/fw-nrfconnect-nrf/tree/nrf9160_samples/samples/nrf9160/simple_at

You can get MNC and MNN data by "AT+COPS?" command.

Compared to mqtt_simple prj.conf file, simple_at program additionally includes these three settings in prj.conf file.

CONFIG_STDOUT_CONSOLE=y
CONFIG_NET_BUF_USER_DATA_SIZE=1
CONFIG_NET_RAW_MODE=y

I omitted these lines in prj.conf and integrated the two programs. It works out, but I'm suspicious that I might do wrong coding. What do you think about this? I'm not familiar with network communication side.

Full code is below. app_socket_start() is added after fds_init().
Thanks.

<prj.conf>

# General config
CONFIG_TEST_RANDOM_GENERATOR=y

# Networking
CONFIG_NETWORKING=y
CONFIG_NET_SOCKETS_OFFLOAD=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_POSIX_NAMES=y

# LTE link control
CONFIG_LTE_LINK_CONTROL=y
CONFIG_LTE_AUTO_INIT_AND_CONNECT=n

# BSD library
CONFIG_BSD_LIBRARY=y

# AT Host
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_AT_HOST_LIBRARY=y

# MQTT
CONFIG_MQTT_LIB=y
CONFIG_MQTT_LIB_TLS=n

# Appliaction
CONFIG_MQTT_PUB_TOPIC="myPubTopic"
CONFIG_MQTT_SUB_TOPIC="mySubTopic"
CONFIG_MQTT_CLIENT_ID="myClientID"
CONFIG_MQTT_BROKER_HOSTNAME="xxxxxxxxxxxxxxxxxxxxxxx"
CONFIG_MQTT_BROKER_PORT=1883

# Main thread
CONFIG_MAIN_THREAD_PRIORITY=7
CONFIG_MAIN_STACK_SIZE=4096

CONFIG_HEAP_MEM_POOL_SIZE=1024

# CONFIG_STDOUT_CONSOLE=y
# CONFIG_NET_BUF_USER_DATA_SIZE=1
# CONFIG_NET_RAW_MODE=y

/*
 * Copyright (c) 2018 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-BSD-5-Clause-Nordic
 */

#include <zephyr.h>
#include <stdio.h>
#include <uart.h>
#include <string.h>

#include <net/mqtt.h>
#include <net/socket.h>
#include <lte_lc.h>

#define MQTT_USERNAME "username"
#define MQTT_PASSWORD "password"

/* Buffers for MQTT client. */
static u8_t rx_buffer[CONFIG_MQTT_MESSAGE_BUFFER_SIZE];
static u8_t tx_buffer[CONFIG_MQTT_MESSAGE_BUFFER_SIZE];
static u8_t payload_buf[CONFIG_MQTT_PAYLOAD_BUFFER_SIZE];

/* The mqtt client struct */
static struct mqtt_client client;

/* MQTT Broker details. */
static struct sockaddr_storage broker;

/* Connected flag */
static bool connected;

/* File descriptor */
static struct pollfd fds;

#if defined(CONFIG_BSD_LIBRARY)

/**@brief Recoverable BSD library error. */
void bsd_recoverable_error_handler(uint32_t err)
{
	printk("bsdlib recoverable error: %u\n", err);
}

/**@brief Irrecoverable BSD library error. */
void bsd_irrecoverable_error_handler(uint32_t err)
{
	printk("bsdlib irrecoverable error: %u\n", err);

	__ASSERT_NO_MSG(false);
}

#endif /* defined(CONFIG_BSD_LIBRARY) */

/**@brief Function to print strings without null-termination
 */
static void data_print(u8_t *prefix, u8_t *data, size_t len)
{
	char buf[len + 1];

	memcpy(buf, data, len);
	buf[len] = 0;
	printk("%s%s\n", prefix, buf);
}

/**@brief Function to publish data on the configured topic
 */
static int data_publish(struct mqtt_client *c, enum mqtt_qos qos,
	u8_t *data, size_t len)
{
	struct mqtt_publish_param param;

	param.message.topic.qos = qos;
	param.message.topic.topic.utf8 = CONFIG_MQTT_PUB_TOPIC;
	param.message.topic.topic.size = strlen(CONFIG_MQTT_PUB_TOPIC);
	param.message.payload.data = data;
	param.message.payload.len = len;
	param.message_id = sys_rand32_get();
	param.dup_flag = 0;
	param.retain_flag = 0;

	data_print("Publishing: ", data, len);
	printk("to topic: %s len: %u\n",
		CONFIG_MQTT_PUB_TOPIC,
		(unsigned int)strlen(CONFIG_MQTT_PUB_TOPIC));

	return mqtt_publish(c, &param);
}

/**@brief Function to subscribe to the configured topic
 */
static int subscribe(void)
{
	struct mqtt_topic subscribe_topic = {
		.topic = {
			.utf8 = CONFIG_MQTT_SUB_TOPIC,
			.size = strlen(CONFIG_MQTT_SUB_TOPIC)
		},
		.qos = MQTT_QOS_1_AT_LEAST_ONCE
	};

	const struct mqtt_subscription_list subscription_list = {
		.list = &subscribe_topic,
		.list_count = 1,
		.message_id = 1234
	};

	printk("Subscribing to: %s len %u\n", CONFIG_MQTT_SUB_TOPIC,
		(unsigned int)strlen(CONFIG_MQTT_SUB_TOPIC));

	return mqtt_subscribe(&client, &subscription_list);
}

/**@brief Function to read the published payload.
 */
static int publish_get_payload(struct mqtt_client *c, size_t length)
{
	u8_t *buf = payload_buf;
	u8_t *end = buf + length;

	if (length > sizeof(payload_buf)) {
		return -EMSGSIZE;
	}

	while (buf < end) {
		int ret = mqtt_read_publish_payload(c, buf, end - buf);

		if (ret < 0) {
			int err;

			if (ret != -EAGAIN) {
				return ret;
			}

			printk("mqtt_read_publish_payload: EAGAIN\n");

			err = poll(&fds, 1, K_SECONDS(CONFIG_MQTT_KEEPALIVE));
			if (err > 0 && (fds.revents & POLLIN) == POLLIN) {
				continue;
			} else {
				return -EIO;
			}
		}

		if (ret == 0) {
			return -EIO;
		}

		buf += ret;
	}

	return 0;
}

/**@brief MQTT client event handler
 */
void mqtt_evt_handler(struct mqtt_client *const c,
		      const struct mqtt_evt *evt)
{
	int err;

	switch (evt->type) {
	case MQTT_EVT_CONNACK:
		if (evt->result != 0) {
			printk("MQTT connect failed %d\n", evt->result);
			break;
		}

		connected = true;
		printk("[%s:%d] MQTT client connected!\n", __func__, __LINE__);
		subscribe();
		break;

	case MQTT_EVT_DISCONNECT:
		printk("[%s:%d] MQTT client disconnected %d\n", __func__,
		       __LINE__, evt->result);

		connected = false;
		break;

	case MQTT_EVT_PUBLISH: {
		const struct mqtt_publish_param *p = &evt->param.publish;

		printk("[%s:%d] MQTT PUBLISH result=%d len=%d\n", __func__,
		       __LINE__, evt->result, p->message.payload.len);
		err = publish_get_payload(c, p->message.payload.len);
		if (err >= 0) {
			data_print("Received: ", payload_buf,
				p->message.payload.len);
			/* Echo back received data */
			data_publish(&client, MQTT_QOS_1_AT_LEAST_ONCE,
				payload_buf, p->message.payload.len);
		} else {
			printk("mqtt_read_publish_payload: Failed! %d\n", err);
			printk("Disconnecting MQTT client...\n");

			err = mqtt_disconnect(c);
			if (err) {
				printk("Could not disconnect: %d\n", err);
			}
		}
	} break;

	case MQTT_EVT_PUBACK:
		if (evt->result != 0) {
			printk("MQTT PUBACK error %d\n", evt->result);
			break;
		}

		printk("[%s:%d] PUBACK packet id: %u\n", __func__, __LINE__,
				evt->param.puback.message_id);
		break;

	case MQTT_EVT_SUBACK:
		if (evt->result != 0) {
			printk("MQTT SUBACK error %d\n", evt->result);
			break;
		}

		printk("[%s:%d] SUBACK packet id: %u\n", __func__, __LINE__,
				evt->param.suback.message_id);
		break;

	default:
		printk("[%s:%d] default: %d\n", __func__, __LINE__,
				evt->type);
		break;
	}
}

/**@brief Resolves the configured hostname and
 * initializes the MQTT broker structure
 */
static void broker_init(void)
{
	int err;
	struct addrinfo *result;
	struct addrinfo *addr;
	struct addrinfo hints = {
		.ai_family = AF_INET,
		.ai_socktype = SOCK_STREAM
	};

	err = getaddrinfo(CONFIG_MQTT_BROKER_HOSTNAME, NULL, &hints, &result);
	if (err) {
		printk("ERROR: getaddrinfo failed %d\n", err);

		return;
	}

	addr = result;
	err = -ENOENT;

	/* Look for address of the broker. */
	while (addr != NULL) {
		/* IPv4 Address. */
		if (addr->ai_addrlen == sizeof(struct sockaddr_in)) {
			struct sockaddr_in *broker4 =
				((struct sockaddr_in *)&broker);

			broker4->sin_addr.s_addr =
				((struct sockaddr_in *)addr->ai_addr)
				->sin_addr.s_addr;
			broker4->sin_family = AF_INET;
			broker4->sin_port = htons(CONFIG_MQTT_BROKER_PORT);
			printk("IPv4 Address found 0x%08x\n",
				broker4->sin_addr.s_addr);
			break;
		} else {
			printk("ai_addrlen = %u should be %u or %u\n",
				(unsigned int)addr->ai_addrlen,
				(unsigned int)sizeof(struct sockaddr_in),
				(unsigned int)sizeof(struct sockaddr_in6));
		}

		addr = addr->ai_next;
		break;
	}

	/* Free the address. */
	freeaddrinfo(result);
}

/**@brief Initialize the MQTT client structure
 */
static void client_init(struct mqtt_client *client)
{
	mqtt_client_init(client);

	broker_init();

    static struct mqtt_utf8 password;
	static struct mqtt_utf8 user_name;

	password.utf8 = (u8_t*)MQTT_PASSWORD;
	password.size = strlen(MQTT_PASSWORD);
	user_name.utf8 = (u8_t*)MQTT_USERNAME;
	user_name.size = strlen(MQTT_USERNAME);

	/* MQTT client configuration */
	client->broker = &broker;
	client->evt_cb = mqtt_evt_handler;
	client->client_id.utf8 = (u8_t *)CONFIG_MQTT_CLIENT_ID;
	client->client_id.size = strlen(CONFIG_MQTT_CLIENT_ID);
	client->password = &password;
	client->user_name = &user_name;
	client->protocol_version = MQTT_VERSION_3_1_1;

	/* MQTT buffers configuration */
	client->rx_buf = rx_buffer;
	client->rx_buf_size = sizeof(rx_buffer);
	client->tx_buf = tx_buffer;
	client->tx_buf_size = sizeof(tx_buffer);

	/* MQTT transport configuration */
	client->transport.type = MQTT_TRANSPORT_NON_SECURE;
}

/**@brief Initialize the file descriptor structure used by poll.
 */
static int fds_init(struct mqtt_client *c)
{
	if (c->transport.type == MQTT_TRANSPORT_NON_SECURE) {
		fds.fd = c->transport.tcp.sock;
	} else {
#if defined(CONFIG_MQTT_LIB_TLS)
		fds.fd = c->transport.tls.sock;
#else
		return -ENOTSUP;
#endif
	}

	fds.events = POLLIN;

	return 0;
}

/**@brief Configures modem to provide LTE link. Blocks until link is
 * successfully established.
 */
static void modem_configure(void)
{
#if defined(CONFIG_LTE_LINK_CONTROL)
	if (IS_ENABLED(CONFIG_LTE_AUTO_INIT_AND_CONNECT)) {
		/* Do nothing, modem is already turned on
		 * and connected.
		 */
	} else {
		int err;

		printk("LTE Link Connecting ...\n");
		err = lte_lc_init_and_connect();
		__ASSERT(err == 0, "LTE link could not be established.");
		printk("LTE Link Connected!\n");
	}
#endif
}

#define RECV_BUF_SIZE 1024
char recv_buf[RECV_BUF_SIZE + 1];

const char *at_commands[] = {
	"AT+COPS?"
	/* Add more here if needed */
};

int blocking_recv(int fd, u8_t *buf, u32_t size, u32_t flags)
{
	int err;

	do {
		err = recv(fd, buf, size, flags);
	} while (err < 0 && errno == EAGAIN);

	return err;
}

int blocking_send(int fd, u8_t *buf, u32_t size, u32_t flags)
{
	int err;

	do {
		err = send(fd, buf, size, flags);
	} while (err < 0 && errno == EAGAIN);

	return err;
}

int blocking_connect(int fd, struct sockaddr *local_addr, socklen_t len)
{
	int err;

	do {
		err = connect(fd, local_addr, len);
	} while (err < 0 && errno == EAGAIN);

	return err;
}

void app_socket_start(void)
{
	int at_socket_fd = socket(AF_LTE, 0, NPROTO_AT);

	printk("Starting simple AT socket application\n\r");

	if (at_socket_fd < 0) {
		printk("Socket err: %d, errno: %d\r\n", at_socket_fd, errno);
	}
	for (int i = 0; i < ARRAY_SIZE(at_commands); i++) {
		int bytes_written = send(at_socket_fd, at_commands[i],
					 strlen(at_commands[i]), 0);
		if (bytes_written > 0) {
			int r_bytes =
				blocking_recv(at_socket_fd, recv_buf,
					      sizeof(recv_buf), MSG_DONTWAIT);
			if (r_bytes > 0) {
				printk("%s", recv_buf);
			}
		}
	}
	printk("Closing socket\n\r");
	(void)close(at_socket_fd);
}


void main(void)
{
	int err;

	printk("The MQTT simple sample started\n");

	modem_configure();

	client_init(&client);

	err = mqtt_connect(&client);
	if (err != 0) {
		printk("ERROR: mqtt_connect %d\n", err);
		return;
	}

	err = fds_init(&client);
	if (err != 0) {
		printk("ERROR: fds_init %d\n", err);
		return;
	}

	while (1) {
        app_socket_start(); // ADD HERE

		err = poll(&fds, 1, K_SECONDS(CONFIG_MQTT_KEEPALIVE)); 
		if (err < 0) {
			printk("ERROR: poll %d\n", errno);
			break;
		}
		
		err = mqtt_live(&client);
		if (err != 0) {
			printk("ERROR: mqtt_live %d\n", err);
			break;
		}

		if ((fds.revents & POLLIN) == POLLIN) {
			err = mqtt_input(&client);
			if (err != 0) {
				printk("ERROR: mqtt_input %d\n", err);
				break;
			}
		}

		if ((fds.revents & POLLERR) == POLLERR) {
			printk("POLLERR\n");
			break;
		}

		if ((fds.revents & POLLNVAL) == POLLNVAL) {
			printk("POLLNVAL\n");
			break;
		}
	}

	printk("Disconnecting MQTT client...\n");

	err = mqtt_disconnect(&client);
	if (err) {
		printk("Could not disconnect MQTT client. Error: %d\n", err);
	}
}

[Øyvind]

Hello again,

Yusuke said:

these three settings in prj.conf file.

Information about configuration options can be found here, in the Zephyr documentation.

Yusuke said:

What do you think about this? I'm not familiar with network communication side.

From the description given in the documentation, I don't see any problems if it works. I have not tested this myself, so if you meet any issues, please let me know.

Kind regards,
Øyvind