基于FreeRTOS与MQTT的物联网技术应用系列——步进电机控制（五）MQTT的移植和步进电机控制的实现

本文在前一篇的基础上进行MQTT的移植，并实现对步进电机驱动器的控制。

分两步完成：
1、移植MQTT协议栈，并进行验证；
2、对步进电机进行控制。

一，移植MQTT协议

参考实现：https://github.com/baoshi/ESP-RTOS-Paho/tree/63c2c74dfe978f215b3bb05f7e1258454908c4fb

以前一篇文章完成的代码为基础，在工程目录下的APP文件夹中新建一个文件夹命名为MQTTClient，
把paho.mqtt.embedded-c源码包中的
paho.mqtt.embedded-c\MQTTPacket\src下的：

    MQTTConnect.h
    MQTTConnectClient.c
    MQTTDeserializePublish.c
    MQTTFormat.h
    MQTTPacket.c
    MQTTPacket.h
    MQTTPublish.h
    MQTTSerializePublish.c
    MQTTSubscribe.h
    MQTTSubscribeClient.c
    MQTTUnsubscribe.h
    MQTTUnsubscribeClient.c
    StackTrace.h

拷贝到MQTTClient文件夹中。
接下来，就是实现两个层面的连接处理：
1、tcp/ip建立连接，或由socket连接完成。
这部分放在

    MQTTFreeRTOSImpl.c
    MQTTFreeRTOSImpl.h

2、MQTT连接。
这部分放在：

    MQTTClient.c
    MQTTClient.h

MQTTFreeRTOSImpl.h的代码如下：

#ifndef MQTTFREERTOSIMPL_H
#define MQTTFREERTOSIMPL_H

#include "FreeRTOS.h"
#include "portmacro.h"

typedef struct Timer Timer;

struct Timer
{
    portTickType end_time;
};

typedef struct Network Network;

struct Network
{
    int my_socket;
    int (*mqttread) (Network*, unsigned char*, int, int);
    int (*mqttwrite) (Network*, unsigned char*, int, int);
};

char expired(Timer*);
void countdown_ms(Timer*, unsigned int);
void countdown(Timer*, unsigned int);
int left_ms(Timer*);

void InitTimer(Timer*);

int FreeRTOS_MQTT_read(Network*, unsigned char*, int, int);
int FreeRTOS_MQTT_write(Network*, unsigned char*, int, int);
void FreeRTOS_MQTT_disconnect(Network*);

void NewNetwork(Network* n);
int ConnectNetwork(Network* n, const char* host, int port);
int DisconnectNetwork(Network* n);


#endif /* MQTTFREERTOSIMPL_H */

MQTTFreeRTOSImpl.c的代码如下：


/*
²Î¿¼https://github.com/baoshi/ESP-RTOS-Paho/tree/63c2c74dfe978f215b3bb05f7e1258454908c4fb
*/

#include <string.h>  
#include "FreeRTOS.h"
#include "portmacro.h"
#include "lwip/sockets.h"
#include "lwip/inet.h"
#include "lwip/netdb.h"
#include "lwip/sys.h"

#include "MQTTFreeRTOSImpl.h"

#define _DEBUG
#include "dprintf.h"

char  expired(Timer* timer)
{
    portTickType now = xTaskGetTickCount();
    int32_t left = timer->end_time - now;
    return (left < 0);
}


void  countdown_ms(Timer* timer, unsigned int timeout)
{
    portTickType now = xTaskGetTickCount();
    timer->end_time = now + timeout / portTICK_RATE_MS;
}


void  countdown(Timer* timer, unsigned int timeout)
{
    countdown_ms(timer, timeout);
}


int  left_ms(Timer* timer)
{
    portTickType now = xTaskGetTickCount();
    int32_t left = timer->end_time - now;
    return (left < 0) ? 0 : left / portTICK_RATE_MS;
}


void  InitTimer(Timer* timer)
{
    timer->end_time = 0;
}

#include "task.h"
#include "timers.h"

__asm void _nop(void)
{   
    nop     
}
void delay(int i)
{
    for(;i>0;i--)
        _nop();
}

int  FreeRTOS_MQTT_read(Network* n, unsigned char* buffer, int len, int timeout_ms)
{
    TickType_t xTicksToWait = timeout_ms / portTICK_PERIOD_MS; /* convert milliseconds to ticks */
    TimeOut_t xTimeOut;
    int recvLen = 0;

    vTaskSetTimeOutState(&xTimeOut); /* Record the time at which this function was entered. */
    do
    {
        int rc = 0;
        lwip_setsockopt(n->my_socket, SOL_SOCKET, SO_RCVTIMEO, &xTicksToWait, sizeof(TickType_t));
        rc = recv(n->my_socket, buffer + recvLen, len - recvLen, 0);
        //dprintf("rc=%d\n",rc);
        delay(50);//must delay enough,otherwise,it will be  blocked
        if (rc >= 0)
            recvLen += rc;  
        else if (rc <0)
        {   
            recvLen = rc;
            break;
        }
    } while (recvLen < len && xTaskCheckForTimeOut(&xTimeOut, &xTicksToWait) == pdFALSE);

    return recvLen;
}


int  FreeRTOS_MQTT_write(Network* n, unsigned char* buffer, int len, int timeout_ms)
{
    TickType_t xTicksToWait = timeout_ms / portTICK_PERIOD_MS; /* convert milliseconds to ticks */
    TimeOut_t xTimeOut;
    int sentLen = 0;

    vTaskSetTimeOutState(&xTimeOut); /* Record the time at which this function was entered. */
    do
    {
        int rc = 0;

        lwip_setsockopt(n->my_socket, SOL_SOCKET, SO_SNDTIMEO, &xTicksToWait, sizeof(xTicksToWait));
        rc = send(n->my_socket, buffer + sentLen, len - sentLen, 0);
        if (rc > 0)
            sentLen += rc;
        else if (rc < 0)
        {
            sentLen = rc;
            break;
        }
    } while (sentLen < len && xTaskCheckForTimeOut(&xTimeOut, &xTicksToWait) == pdFALSE);

    return sentLen;
}



void  NewNetwork(Network* n)
{
    n->my_socket = -1;
    n->mqttread = FreeRTOS_MQTT_read;
    n->mqttwrite = FreeRTOS_MQTT_write;
}


int  host2addr(const char *hostname , struct in_addr *in)
{
    struct addrinfo hints, *servinfo, *p;
    struct sockaddr_in *h;
    int rv;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    rv = getaddrinfo(hostname, 0 , &hints , &servinfo);
    if (rv != 0)
    {
        return rv;
    }

    // loop through all the results and get the first resolve
    for (p = servinfo; p != 0; p = p->ai_next)
    {
        h = (struct sockaddr_in *)p->ai_addr;
        in->s_addr = h->sin_addr.s_addr;
    }
    freeaddrinfo(servinfo); // all done with this structure
    return 0;
}


int  ConnectNetwork(Network* n, const char* host, int port)
{
    struct sockaddr_in addr;
    int ret;

    if (host2addr(host, &(addr.sin_addr)) != 0)
    {
        return -1;
    }

    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);

    n->my_socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if( n->my_socket < 0 )
    {
        // error
        return -1;
    }
    ret = connect(n->my_socket, ( struct sockaddr *)&addr, sizeof(struct sockaddr_in));
    if( ret < 0 )
    {
        // error
        lwip_close(n->my_socket);
        return ret;
    }

    return ret;
}


int  DisconnectNetwork(Network* n)
{
    lwip_close(n->my_socket);
    n->my_socket = -1;
    return 0;
}

MQTTClient.h代码如下：

/*******************************************************************************
 * Copyright (c) 2014 IBM Corp.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Allan Stockdill-Mander/Ian Craggs - initial API and implementation and/or initial documentation
 *******************************************************************************/

#ifndef __MQTT_CLIENT_C_
#define __MQTT_CLIENT_C_

#include "MQTTPacket.h"
#include "MQTTFreeRTOSImpl.h"

#define MAX_PACKET_ID 65535
#define MAX_MESSAGE_HANDLERS 5
#define MAX_FAIL_ALLOWED  2

enum QoS { QOS0, QOS1, QOS2 };

// all failure return codes must be negative
enum returnCode {DISCONNECTED = -3, BUFFER_OVERFLOW = -2, FAILURE = -1, SUCCESS = 0 };

void NewTimer(Timer*);

typedef struct _MQTTMessage
{
    enum QoS qos;
    char retained;
    char dup;
    unsigned short id;
    void *payload;
    size_t payloadlen;
} MQTTMessage;

typedef struct _MessageData
{
    MQTTString* topic;
    MQTTMessage* message;
} MessageData;

typedef void (*messageHandler)(MessageData*);

struct _MQTTClient
{
    unsigned int next_packetid;
    unsigned int command_timeout_ms;
    size_t buf_size, readbuf_size;
    unsigned char *buf;  
    unsigned char *readbuf; 
    unsigned int keepAliveInterval;
    char ping_outstanding;
    int fail_count;
    int isconnected;

    struct MessageHandlers
    {
        const char* topicFilter;
        void (*fp) (MessageData*);
    } messageHandlers[MAX_MESSAGE_HANDLERS];      // Message handlers are indexed by subscription topic

    void (*defaultMessageHandler) (MessageData*);

    Network* ipstack;
    Timer ping_timer;
};


typedef struct _MQTTClient MQTTClient;


int MQTTConnect(MQTTClient* c, MQTTPacket_connectData* options);
int MQTTPublish(MQTTClient* c, const char* topic, MQTTMessage* message);
int MQTTSubscribe(MQTTClient* c, const char* topic, enum QoS qos, messageHandler handler);
int MQTTUnsubscribe(MQTTClient* c, const char* topic);
int MQTTDisconnect(MQTTClient* c);
int MQTTYield(MQTTClient* c, int timeout_ms);

void NewMQTTClient(MQTTClient*, Network*, unsigned int, unsigned char*, size_t, unsigned char*, size_t);

#define DefaultClient {0, 0, 0, 0, NULL, NULL, 0, 0, 0}

#endif

MQTTClient.c的代码如下：

/*******************************************************************************
 * Copyright (c) 2014 IBM Corp.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Allan Stockdill-Mander/Ian Craggs - initial API and implementation and/or initial documentation
 *******************************************************************************/

#include "MQTTClient.h"

//#define _DEBUG
#include "dprintf.h"

void  NewMessageData(MessageData* md, MQTTString* aTopicName, MQTTMessage* aMessgage) {
    md->topic = aTopicName;
    md->message = aMessgage;
}


int  getNextPacketId(MQTTClient *c) {
    return c->next_packetid = (c->next_packetid == MAX_PACKET_ID) ? 1 : c->next_packetid + 1;
}


int  sendPacket(MQTTClient* c, int length, Timer* timer)
{
    int rc = FAILURE, 
        sent = 0;

    while (sent < length && !expired(timer))
    {
        rc = c->ipstack->mqttwrite(c->ipstack, &c->buf[sent], length, left_ms(timer));
        if (rc < 0)  // there was an error writing the data
            break;
        sent += rc;
    }
    if (sent == length)
    {
        countdown(&(c->ping_timer), c->keepAliveInterval); // record the fact that we have successfully sent the packet
        rc = SUCCESS;
    }
    else
        rc = FAILURE;
    return rc;
}


int  decodePacket(MQTTClient* c, int* value, int timeout)
{
    unsigned char i;
    int multiplier = 1;
    int len = 0;
    const int MAX_NO_OF_REMAINING_LENGTH_BYTES = 4;

    *value = 0;
    do
    {
        int rc = MQTTPACKET_READ_ERROR;

        if (++len > MAX_NO_OF_REMAINING_LENGTH_BYTES)
        {
            rc = MQTTPACKET_READ_ERROR; /* bad data */
            goto exit;
        }
        rc = c->ipstack->mqttread(c->ipstack, &i, 1, timeout);
        if (rc != 1)
            goto exit;
        *value += (i & 127) * multiplier;
        multiplier *= 128;
    } while ((i & 128) != 0);
exit:
    return len;
}


int  readPacket(MQTTClient* c, Timer* timer)
{
    int rc = FAILURE;
    MQTTHeader header = {0};
    int len = 0;
    int rem_len = 0;
    int data_real_len=0;

    /* 1. read the header byte.  This has the packet type in it */
    if (c->ipstack->mqttread(c->ipstack, c->readbuf, 1, left_ms(timer)) != 1)
        goto exit; 

    len = 1;
    /* 2. read the remaining length.  This is variable in itself */
    decodePacket(c, &rem_len, left_ms(timer)); 
    len += MQTTPacket_encode(c->readbuf + 1, rem_len); /* put the original remaining length back into the buffer */

    /* 3. read the rest of the buffer using a callback to supply the rest of the data */
    if (rem_len > 0 && ((data_real_len=c->ipstack->mqttread(c->ipstack, c->readbuf + len, rem_len, left_ms(timer))) != rem_len))
    {   
        goto exit;
    }
#if 0 /* Commented @ 2017-Apr-25 1:34:59 */
    else
    {
        int i;
        dprintf("data len=%d ,,,, data_real_len=%d\n",rem_len,data_real_len);
        dprintf("c->readbuf=%p\n",c->readbuf);

        for(i=0;i<data_real_len;i++)
        {
            printf("%02X ,",c->readbuf[i]);
            if(i%10==9)
                printf("\n");
        }
    }
#endif /* Commented */

    header.byte = c->readbuf[0];
    rc = header.bits.type;
exit:
    dprintf("readPacket=%d\n", rc);
    return rc;
}


// assume topic filter and name is in correct format
// # can only be at end
// + and # can only be next to separator
char  isTopicMatched(char* topicFilter, MQTTString* topicName)
{
    char* curf = topicFilter;
    char* curn = topicName->lenstring.data;
    char* curn_end = curn + topicName->lenstring.len;

    while (*curf && curn < curn_end)
    {
        if (*curn == '/' && *curf != '/')
            break;
        if (*curf != '+' && *curf != '#' && *curf != *curn)
            break;
        if (*curf == '+')
        {   // skip until we meet the next separator, or end of string
            char* nextpos = curn + 1;
            while (nextpos < curn_end && *nextpos != '/')
                nextpos = ++curn + 1;
        }
        else if (*curf == '#')
            curn = curn_end - 1;    // skip until end of string
        curf++;
        curn++;
    };

    return (curn == curn_end) && (*curf == '\0');
}


int  deliverMessage(MQTTClient* c, MQTTString* topicName, MQTTMessage* message)
{
    int i;
    int rc = FAILURE;

    // we have to find the right message handler - indexed by topic
    for (i = 0; i < MAX_MESSAGE_HANDLERS; ++i)
    {
        if (c->messageHandlers[i].topicFilter != 0 && (MQTTPacket_equals(topicName, (char*)c->messageHandlers[i].topicFilter) ||
                isTopicMatched((char*)c->messageHandlers[i].topicFilter, topicName)))
        {
            if (c->messageHandlers[i].fp != NULL)
            {
                MessageData md;
                NewMessageData(&md, topicName, message);
                c->messageHandlers[i].fp(&md);
                rc = SUCCESS;
            }
        }
    }

    if (rc == FAILURE && c->defaultMessageHandler != NULL) 
    {
        MessageData md;
        NewMessageData(&md, topicName, message);
        c->defaultMessageHandler(&md);
        rc = SUCCESS;
    }   

    return rc;
}

int  keepalive(MQTTClient* c)
{
    int rc = SUCCESS;

    if (c->keepAliveInterval == 0)
    {   
        rc = SUCCESS;
        goto exit;
    }

    if (expired(&(c->ping_timer)))
    {   
        if (c->ping_outstanding)
        {   
            // if ping failure accumulated above MAX_FAIL_ALLOWED, the connection is broken
            ++(c->fail_count);
            if (c->fail_count >= MAX_FAIL_ALLOWED)
            {   
                rc = DISCONNECTED;
                goto exit;
            }
        }
        else
        {
            Timer timer;
            int len;
            InitTimer(&timer);
            countdown_ms(&timer, 1000);
            c->ping_outstanding = 1;
            len = MQTTSerialize_pingreq(c->buf, c->buf_size);
            if (len > 0){dprintf("send ping\n");
                sendPacket(c, len, &timer);}
        }
        // re-arm ping counter
        countdown(&(c->ping_timer), c->keepAliveInterval);
    }

exit:
    return rc;
}

int  cycle(MQTTClient* c, Timer* timer)
{   
    // read the socket, see what work is due
    int packet_type = readPacket(c, timer);

    int len = 0,
        rc = SUCCESS;
    dprintf("packet_type=%d\n",packet_type);
    switch (packet_type)
    {
        case CONNACK:
        case PUBACK:
        case SUBACK:
            break;
        case PUBLISH:
        {   
            MQTTString topicName;
            MQTTMessage msg;
            if (MQTTDeserialize_publish((unsigned char*)&msg.dup, (int*)&msg.qos, (unsigned char*)&msg.retained, (unsigned short*)&msg.id, &topicName,
               (unsigned char**)&msg.payload, (int*)&msg.payloadlen, c->readbuf, c->readbuf_size) != 1)
                goto exit;
            deliverMessage(c, &topicName, &msg);
            if (msg.qos != QOS0)
            {
                if (msg.qos == QOS1)
                    len = MQTTSerialize_ack(c->buf, c->buf_size, PUBACK, 0, msg.id);
                else if (msg.qos == QOS2)
                    len = MQTTSerialize_ack(c->buf, c->buf_size, PUBREC, 0, msg.id);
                if (len <= 0)
                    rc = FAILURE;
                else
                    rc = sendPacket(c, len, timer);
                if (rc == FAILURE)
                    goto exit; // there was a problem
            }
            break;
        }
        case PUBREC:
        {  
            unsigned short mypacketid;
            unsigned char dup, type;
            if (MQTTDeserialize_ack(&type, &dup, &mypacketid, c->readbuf, c->readbuf_size) != 1)
                rc = FAILURE;
            else if ((len = MQTTSerialize_ack(c->buf, c->buf_size, PUBREL, 0, mypacketid)) <= 0)
                rc = FAILURE;
            else if ((rc = sendPacket(c, len, timer)) != SUCCESS) // send the PUBREL packet
                rc = FAILURE; // there was a problem
            if (rc == FAILURE)
                goto exit; // there was a problem
            break;
        }
        case PUBCOMP:
            break;
        case PINGRESP:
            {   
                c->ping_outstanding = 0;
                c->fail_count = 0;
            }
            break;
    }
    if (c->isconnected)
        rc = keepalive(c);
exit:
    if (rc == SUCCESS)
        rc = packet_type;
    return rc;
}


void  NewMQTTClient(MQTTClient* c, Network* network, unsigned int command_timeout_ms, unsigned char* buf, size_t buf_size, unsigned char* readbuf, size_t readbuf_size)
{
    int i;
    c->ipstack = network;

    for (i = 0; i < MAX_MESSAGE_HANDLERS; ++i)
        c->messageHandlers[i].topicFilter = 0;
    c->command_timeout_ms = command_timeout_ms;
    c->buf = buf;
    c->buf_size = buf_size;
    c->readbuf = readbuf;
    c->readbuf_size = readbuf_size;
    c->isconnected = 0;
    c->ping_outstanding = 0;
    c->fail_count = 0;
    c->defaultMessageHandler = NULL;
    InitTimer(&(c->ping_timer));
}


int  MQTTYield(MQTTClient* c, int timeout_ms)
{
    int rc = SUCCESS;
    Timer timer;

    InitTimer(&timer);    
    countdown_ms(&timer, timeout_ms);
    while (!expired(&timer))
    {   
        rc = cycle(c, &timer);
        // cycle could return 0 or packet_type or 65535 if nothing is read
        // cycle returns DISCONNECTED only if keepalive() fails.
        if (rc == DISCONNECTED)
            break;
        rc = SUCCESS;
    }
    return rc;
}


// only used in single-threaded mode where one command at a time is in process
int  waitfor(MQTTClient* c, int packet_type, Timer* timer)
{
    int rc = FAILURE;

    do
    {
        if (expired(timer)) 
            break; // we timed out
    }
    while ((rc = cycle(c, timer)) != packet_type);  

    return rc;
}


int  MQTTConnect(MQTTClient* c, MQTTPacket_connectData* options)
{
    Timer connect_timer;
    int rc = FAILURE;
    MQTTPacket_connectData default_options = MQTTPacket_connectData_initializer;
    int len = 0;

    InitTimer(&connect_timer);
    countdown_ms(&connect_timer, c->command_timeout_ms);

    if (c->isconnected) // don't send connect packet again if we are already connected
        goto exit;

    if (options == 0)
        options = &default_options; // set default options if none were supplied

    c->keepAliveInterval = options->keepAliveInterval;
    countdown(&(c->ping_timer), c->keepAliveInterval);

    if ((len = MQTTSerialize_connect(c->buf, c->buf_size, options)) <= 0)
        goto exit;
    if ((rc = sendPacket(c, len, &connect_timer)) != SUCCESS)  // send the connect packet
        goto exit; // there was a problem

    // this will be a blocking call, wait for the connack
    if (waitfor(c, CONNACK, &connect_timer) == CONNACK)
    {
        unsigned char connack_rc = 255;
        char sessionPresent = 0;
        if (MQTTDeserialize_connack((unsigned char*)&sessionPresent, &connack_rc, c->readbuf, c->readbuf_size) == 1)
            rc = connack_rc;
        else
            rc = FAILURE;
    }
    else
        rc = FAILURE;

exit:
    if (rc == SUCCESS)
        c->isconnected = 1;
    return rc;
}


int  MQTTSubscribe(MQTTClient* c, const char* topic, enum QoS qos, messageHandler handler)
{ 
    int rc = FAILURE;  
    Timer timer;
    int len = 0;
    MQTTString topicStr = MQTTString_initializer;
    topicStr.cstring = (char *)topic;

    InitTimer(&timer);
    countdown_ms(&timer, c->command_timeout_ms);
    if (!c->isconnected)
        goto exit;

    len = MQTTSerialize_subscribe(c->buf, c->buf_size, 0, getNextPacketId(c), 1, &topicStr, (int*)&qos);
    if (len <= 0)
        goto exit;
    if ((rc = sendPacket(c, len, &timer)) != SUCCESS) // send the subscribe packet
    {
        goto exit;             // there was a problem
    }

    if (waitfor(c, SUBACK, &timer) == SUBACK)      // wait for suback 
    {
        int count = 0, grantedQoS = -1;
        unsigned short mypacketid;
        if (MQTTDeserialize_suback(&mypacketid, 1, &count, &grantedQoS, c->readbuf, c->readbuf_size) == 1)
            rc = grantedQoS; // 0, 1, 2 or 0x80
        if (rc != 0x80)
        {
            int i;
            for (i = 0; i < MAX_MESSAGE_HANDLERS; ++i)
            {
                if (c->messageHandlers[i].topicFilter == 0)
                {
                    c->messageHandlers[i].topicFilter = topic;
                    c->messageHandlers[i].fp = handler;
                    rc = 0;
                    break;
                }
            }
        }
    }
    else
        rc = FAILURE;

exit:
    return rc;
}


int  MQTTUnsubscribe(MQTTClient* c, const char* topicFilter)
{   
    int rc = FAILURE; 
    int len = 0;
    Timer timer;    
    MQTTString topic = MQTTString_initializer;
    topic.cstring = (char *)topicFilter;


    InitTimer(&timer);
    countdown_ms(&timer, c->command_timeout_ms);

    if (!c->isconnected)
        goto exit;

    if ((len = MQTTSerialize_unsubscribe(c->buf, c->buf_size, 0, getNextPacketId(c), 1, &topic)) <= 0)
        goto exit;
    if ((rc = sendPacket(c, len, &timer)) != SUCCESS) // send the subscribe packet
        goto exit; // there was a problem

    if (waitfor(c, UNSUBACK, &timer) == UNSUBACK)
    {
        unsigned short mypacketid;  // should be the same as the packetid above
        if (MQTTDeserialize_unsuback(&mypacketid, c->readbuf, c->readbuf_size) == 1)
            rc = 0; 
    }
    else
        rc = FAILURE;

exit:
    return rc;
}


int  MQTTPublish(MQTTClient* c, const char* topic, MQTTMessage* message)
{
    int rc = FAILURE;
    int len = 0;
    Timer timer;   
    MQTTString topicStr = MQTTString_initializer;
    topicStr.cstring = (char *)topic;


    InitTimer(&timer);
    countdown_ms(&timer, c->command_timeout_ms);

    if (!c->isconnected)
        goto exit;

    if (message->qos == QOS1 || message->qos == QOS2)
        message->id = getNextPacketId(c);

    len = MQTTSerialize_publish(c->buf, c->buf_size, 0, message->qos, message->retained, message->id, 
              topicStr, (unsigned char*)message->payload, message->payloadlen);
    if (len <= 0)
        goto exit;
    if ((rc = sendPacket(c, len, &timer)) != SUCCESS) // send the subscribe packet
    {
        goto exit; // there was a problem
    }

    if (message->qos == QOS1)
    {
        if (waitfor(c, PUBACK, &timer) == PUBACK)
        {
            unsigned short mypacketid;
            unsigned char dup, type;
            // We still can receive from broker, treat as recoverable
            c->fail_count = 0;
            if (MQTTDeserialize_ack(&type, &dup, &mypacketid, c->readbuf, c->readbuf_size) != 1)
                rc = FAILURE;
            else
                rc = SUCCESS;
        }
        else
        {
            rc = FAILURE;
        }

    }
    else if (message->qos == QOS2)
    {
        if (waitfor(c, PUBCOMP, &timer) == PUBCOMP)
        {
            unsigned short mypacketid;
            unsigned char dup, type;
            // We still can receive from broker, treat as recoverable
            c->fail_count = 0;
            if (MQTTDeserialize_ack(&type, &dup, &mypacketid, c->readbuf, c->readbuf_size) != 1)
                rc = FAILURE;
            else
                rc = SUCCESS;
        }
        else
        {
            rc = FAILURE;
        }
    }

exit:
    return rc;
}


int  MQTTDisconnect(MQTTClient* c)
{  
    int rc = FAILURE;
    Timer timer;     // we might wait for incomplete incoming publishes to complete
    int len = MQTTSerialize_disconnect(c->buf, c->buf_size);

    InitTimer(&timer);
    countdown_ms(&timer, c->command_timeout_ms);

    if (len > 0)
        rc = sendPacket(c, len, &timer);            // send the disconnect packet

    c->isconnected = 0;
    return rc;
}

把MQTTClient.c和MQTTFreeRTOSImpl.c加入到IDE中，并把..\APP\MQTTClient和..\APP加入到包含路径中。

编译一下通过。

然后写个测试程序：TestTask.c：

#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "MQTTClient.h"
#include <stdio.h>

//#define _DEBUG
#include "dprintf.h"

#define USR_SD_CARD_INI

// testing mosquitto server
#define MQTT_HOST "10.0.0.108"
#define MQTT_PORT 1883
#define MQTT_USER ""
#define MQTT_PASS ""
#define mqtt_client_id "MQTT on STM32"

#define SUB_TOPIC_1 "FCS/out"


void  topic_received(MessageData* md)
{
    int i;
    MQTTMessage* message = md->message;
    printf("Received Topic[");
    for (i = 0; i < md->topic->lenstring.len; ++i)
        printf("%c",md->topic->lenstring.data[i]);
    printf("], Message[ ");
    for (i = 0; i < (int)message->payloadlen; ++i)
        printf("%c",((char*)message->payload)[i]);
    printf("]\n");
}



xQueueHandle publish_queue;
#define PUB_MSG_LEN 16

#include "common.h"

void mqtt_task(void *pvParameters)
{
    int ret;
    struct Network network;
    MQTTClient client = DefaultClient;
    //char mqtt_client_id[20];
    unsigned char mqtt_buf[100];
    unsigned char mqtt_readbuf[100];

    MQTTPacket_connectData data = MQTTPacket_connectData_initializer;

    NewNetwork(&network);
    while (1)
    {

            #ifndef USR_SD_CARD_INI
        printf("(Re)connecting to MQTT server %s ... ", MQTT_HOST);
        ret = ConnectNetwork(&network, MQTT_HOST, MQTT_PORT);
            #else
                if(InitMQTTServerInfo()<0)
                    continue;
        printf("(Re)connecting to MQTT server %s:%d ... ", getMQTTServerIP(),getMQTTServerPort());
        ret = ConnectNetwork(&network, getMQTTServerIP(), getMQTTServerPort());
            #endif
        if (!ret)
        {
            printf("ok.\r\n");
            NewMQTTClient(&client, &network, 1000, mqtt_buf, 100, mqtt_readbuf, 100);
            data.willFlag = 0;
            data.MQTTVersion = 3;
            data.clientID.cstring = mqtt_client_id;
                    #ifndef USR_SD_CARD_INI
            data.username.cstring = MQTT_USER;
            data.password.cstring = MQTT_PASS;                  
                    #else
            data.username.cstring = getMQTTServerName();
            data.password.cstring = getMQTTServerPassword();
                    #endif
            data.keepAliveInterval = 60;
            data.cleansession = 1;
            printf("Send MQTT connect ...");
            ret = MQTTConnect(&client, &data);
            if (!ret)
            {
                printf("ok.\r\n");
                // Subscriptions
                MQTTSubscribe(&client, SUB_TOPIC_1, QOS1, topic_received);
                // Empty the publish queue
                xQueueReset(publish_queue);dprintf("\n");
                while (1)
                {   
                                        dprintf("\n");
                    // Receiving / Ping
                    ret = MQTTYield(&client, 1000);
                                        dprintf("\n");
                    if (ret == DISCONNECTED)
                    {  
                                                dprintf("DISCONNECTED\n");
                        break;
                    }
                }
                printf("Connection broken, request restart\r\n");
            }
            else
            {
                printf("failed.\r\n");
            }
            DisconnectNetwork(&network);dprintf("\n");
        }
        else
        {
            printf("failed.\r\n");
        }
        vTaskDelay(1000 / portTICK_RATE_MS);
    }
    printf("MQTT task ended ,ret=%d\n", ret);
    vTaskDelete(NULL);
}

#define MQTTClient_TASK_PRIO    ( tskIDLE_PRIORITY+2 )

void testTask(void)
{
    printf("MQTT:  TestTask started...\n");
    publish_queue = xQueueCreate(3, PUB_MSG_LEN);
    xTaskCreate(mqtt_task, "mqtt", 1024, NULL, MQTTClient_TASK_PRIO, NULL);
}

这部分代码如果没有用sd卡的话，可以把

#define USR_SD_CARD_INI

注释掉，并把：

#define MQTT_HOST "10.0.0.108"

修改为待连接的ip地址。

然后，把它存到APP目录下，并加入到IDE上。
然后修改一下BSP/netconf.c，在路由动态分配IP，打印消息以后，加入下面代码：

                        extern void testTask(void);
                        testTask();

意思是，当动态IP分配完毕之后，立即创建一个任务，来执行我们的MQTT测试。
编译链接，把hex档烧到开发板上，然后上电运行。

对了，板子上电前别忘了把sd卡中的ip配置文件修改成本地电脑的ip：

[server]
ip=10.0.0.108
port=1883
name=
password=

好了，下面验证一下：
在电脑上打开cmd，启动mosquitto
（参考：基于mini2440嵌入式linux上整合一套Domoticz智能家居系统（四）交叉编译OpenSSL、c-ares、e2fsprogs和mosquitto）

可以看到：

好了，MQTT已经跑起来了。
心跳包也正常。

然后，我们再开一个cmd窗口，用mosquito发一个话题为FCS/out的消息如下：

mosquitto_pub -h 127.0.0.1 -m "{idx:0,act:1}" -t "FCS/out"

可以看到：

已经收到消息了。
说明MQTTClient程序工作正常。

接下来我们做一个mosquitto_pub另外的一种使用方法来测试一下。

因为后面我们将会发送带有换行符的消息，这样我们在应用程序中可以借用换行符来对消息进行解析。
而在测试中，不能使用mosquitto_pub命令行直接输入消息文本的方式来发送带有换行符的消息。幸好，mosquitto_pub有另一种方法，就是发送文件数据，有两种方式：
1、mosquitto_pub -t my/topic -f ./data
2、mosquitto_pub -t my/topic -s < ./data
参考：https://mosquitto.org/man/mosquitto_pub-1.html

我们选用了第二种方式。

为了测试，我们写一个批处理文件，来临时性的设置windows下的path环境变量，以便在本地目录中使用mosquito命令行程序：

@set path==%path%;%MOSQUITTO_DIR%"
@cmd.exe

把以上代码保存为：test.bat

然后双击运行：

然后我们创建两个文本文件：mytxt1.txt、mytxt2.txt
内容分别如下：
mytxt1.txt：

{
idx:0,
act:1
}

mytxt2.txt

{
idx:0,
act:0
}

把两个文本跟test.bat放在同目录下。
然后在刚才test.bat调出来的cmd界面上就可以使用下面两行命令进行测试了：

mosquitto_pub -t "FCS/out" -s < ./mytxt1.txt


mosquitto_pub -t "FCS/out" -s < ./mytxt2.txt

可以看到：

ok，测试完成。
以上完整代码下载地址：
STM32F107_FreeRTOS_v9.0.0_SDCard-FatFS_LwIP-1.4.1_MQTT.rar

二、对步进电机进行控制

本人使用的是16细分的步进电机驱动器，型号为 ：ZD6560 v3c

使用共阴极的接法：

STM32芯片管脚跟电机驱动器的对应关系如下：
PC5（定义为Dir） ——–DIR
PC6（定义为Free） ——-EN
PC7（定义为Pulse）——-CP

脱机使能逻辑为：
0或悬空：正常工作（hold）；
1：脱机。

所谓正常工作是指，无论有无脉冲，驱动器对电机线圈都一直供电，如果有脉冲，则按脉冲数据供电；
所谓脱机是指，无论有无脉冲，驱动器对电机线圈都不供电。

关于步进电机控制的设置说明：

我们使用的设置：

上图是侧面的拨码开关，向下是ON，向上是OFF。

SW7	SW6	SW6	SW4	SW3	SW2	SW1
OFF	ON	OFF	ON	OFF	OFF	ON

按照说明书的设置规范，我们目前使用的是
16细分
电流1.2A
衰减：慢

本文的STM32芯片使用GPIO在硬件定时器的控制下输出方波的方式提供电机驱动器所需脉冲，之所以这样是因为本文需要对步进电机的步数进行统计和控制。因此，代码中使用了硬件定时器（TIM4）。进而需要在启动代码stm32f10x.s中开启TIM4的定时中断，并在stm32fx_it.c中添加定时器中断服务程序代码。还需要添加TIM4的配置初始化代码等。

对于MQTT消息的解析部分的程序框架可以参考：
基于mini2440嵌入式linux上整合一套Domoticz智能家居系统（九）使用domoticz+mosquitto+Android客户端实现控制mini2440上的LED（二）

由于代码比较多，就不一一贴上来了。

完整源代码下载地址：
STM32F107_FreeRTOS_v9.0.0_SDCard-FatFS_LwIP-1.4.1_MQTT_StepMotor.rar

稍微说明一下：
本代码中的步进电机控制只是验证性的控制，如用在实际控制环境中还需要进一步完善或修改。

还是发几张效果图吧：

下一篇，将使用CrossApp框架是用mosquitto库开发PC端或移动端的对步进电机的控制应用程序。