在物联网项目的开发过程中，必不可少的一项功能就是远程升级OTA（Over-the-Air），即使用WIFI、蓝牙、4G、NB-IOT等方式将升级包传输到MCU，MCU进行代码存储，完成升级
本系列文章将介绍基于电信AEP平台进行NB-IOT设备的远程升级，包含stm32内部flash分区、BootLoader代码编写，平台软件升级包制作，平台软件升级协议对接及参考源码等内容，后续几篇文章将陆续介绍
该系列文章目录大纲如下：
在前面两篇文章：NBIOT远程升级第1弹：BootLoader编写及软件包制作 中，介绍了BootLoader编写的几个要点及电信AEP平台软件包的制作
NB-IOT远程升级第2弹：软件升级协议、流程 介绍电信AEP平台远程升级使用的PCP协议，以及使用串口助手模拟远程升级流程，为后面敲代码做准备。
这一节通过分析一个开源的FOTA代码，进一步加深对PCP协议及平台远程升级流程的理解，方面大家自己做移植
1、源码介绍
基于小熊派开发板的ota远程升级代码案例，运行硬件环境如下所示：
结合参考案例代码与上一节 NB-IOT远程升级第2弹：软件升级协议、流程 的内容联合起来看，会达到事半功倍的效果，你会发现远程升级就那么回事，也没想象中的那么难。
2、源码分析
源码也挺简单的，大概介绍下主要流程的函数
2.1 接收数据解析
接收到电信AEP平台下发的数据，对数据进行解析，判断是不是PCP协议，是否是远程升级的相关命令。
可解析出起始标识位、版本号、消息码、校验码、数据区长度和数据区。
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
int32_t sota_parse(const int8_t *in_buf, int32_t in_len, int8_t * out_buf, int32_t out_len) {
ota_pcp_head_s *phead;
char *databuf;
char *rlen;
int buflen;
int ret,cmd_crc_num;
char *buf;
if (in_buf == NULL || in_len < (sizeof(ota_pcp_head_s) - sizeof(WORD)) || out_buf == NULL)
{
SOTA_LOG("in_buf:%p len:%d, out_buf:%p",in_buf,(int)in_len, out_buf);
goto END;
}
rlen = strstr((const char*)in_buf,":");/*lint !e158*/
if (rlen == NULL)/*lint !e158*/
{
SOTA_LOG("buflen invalid");
goto END;
}
buflen = chartoint(rlen+1);
if (out_len < buflen)
{
SOTA_LOG("out buf not enough");
goto END;
}
buflen = buflen * 2;
databuf = strstr(rlen,",");
if (databuf == NULL)
{
SOTA_LOG("buf invalid");
goto END;
}
buf = databuf + 1;
memset(out_buf, 0, out_len);
HexStrToByte((const unsigned char *)buf, (unsigned char *)out_buf, buflen);
phead = (ota_pcp_head_s *)out_buf;
cmd_crc_num = htons_ota(phead->chk_code);
phead->chk_code = 0;
ret = crc_check((const unsigned char *)out_buf, buflen/2);
phead->ori_id = htons_ota(phead->ori_id);
if (phead->data_len > BLOCK_HEAD && phead->msg_code == MSG_GET_BLOCK)
{
phead->data_len = htons_ota(phead->data_len) - BLOCK_HEAD;
}
if (phead->ori_id != PCP_HEAD || (ret != cmd_crc_num) || \
(phead->msg_code < MSG_GET_VER || phead->msg_code > MSG_NOTIFY_STATE))
{
SOTA_LOG("head wrong! head magic:%X msg_code:%X ver_num:%X ret:%X crc:%X",
phead->ori_id,phead->msg_code,phead->ver_num, ret, cmd_crc_num);
goto END;
}
return SOTA_OK;
END:
return SOTA_FAILED;
}` </pre>
2.2 升级流程状态机
远程升级的流程状态机，根据平台下发命令的消息码作为状态标志
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
int32_t sota_process(void *arg, const int8_t *buf, int32_t buflen) {
char sbuf[64] = {0};
const uint8_t *pbuf = NULL;
int ret = SOTA_OK;
ota_pcp_head_s *phead;
unsigned char msg_code;
phead =(ota_pcp_head_s *)buf;
msg_code = phead->msg_code;
if (phead->data_len > 0)
{
pbuf = (uint8_t *)buf + VER_LEN/2;
}
SOTA_LOG("process sota msg %d", msg_code);
switch (msg_code)
{
case MSG_GET_VER:
{
char ver_ret[VER_LEN + 1] = {0};
(void)g_flash_op.get_ver(ver_ret+1, VER_LEN);
(void)ver_to_hex(ver_ret, (VER_LEN + 1), (char *)sbuf);
(void)sota_at_send(MSG_GET_VER, (char *)sbuf, (VER_LEN + 1) * 2);
ret = SOTA_OK;
break;
}
case MSG_NOTIFY_NEW_VER:
{
if (phead->data_len > sizeof(ota_ver_notify_t))
{
ret = sota_new_ver_process(phead, pbuf);
}
else
{
ret = SOTA_INVALID_PACKET;
}
break;
}
case MSG_GET_BLOCK:
{
if (phead->data_len > 0)
{
ret = sota_data_block_process(phead, pbuf);
}
else
{
ret = SOTA_INVALID_PACKET;
}
break;
}
case MSG_EXC_UPDATE:
{
ret = sota_update_exc_process(phead, pbuf);
break;
}
default:
{
SOTA_LOG("Rx invalid packet");
ret = SOTA_INVALID_PACKET;
break;
}
}
return ret;
}` </pre>
2.3 设备应答
设备往平台发送应答消息的接口函数
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
static void sota_send_response_code(msg_code_e msg_code, response_code_e code) {
char ret_buf[1];
char sbuf[2];
ret_buf[0] = code;
(void)ver_to_hex(ret_buf, 1, (char *)sbuf);
(void)sota_at_send(msg_code, (char *)sbuf, 2);
}` </pre>
2.3 设备发送数据
设备往平台发送数据的接口函数
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
static int sota_at_send(msg_code_e msg_code, char *buf, int len)
{
uint32_t ret;
char crcretbuf[5] = {0};
char tmpbuf[SEND_BUF_LEN + VER_LEN] = {0};
ota_pcp_head_s pcp_head = {0};
unsigned char atwbuf[SEND_BUF_LEN + VER_LEN] = {0};
unsigned char hbuf[64] = {0};
if (len >= SEND_BUF_LEN)
{
SOTA_LOG("payload too long");
return SOTA_FAILED;
}
pcp_head.ori_id = htons_ota(PCP_HEAD);
pcp_head.ver_num = 1;
pcp_head.msg_code = msg_code;
pcp_head.data_len = htons_ota(len / 2);
(void)ver_to_hex((const char *)&pcp_head, sizeof(ota_pcp_head_s), (char *)hbuf);
memcpy(atwbuf, hbuf, VER_LEN);
memcpy(atwbuf + VER_LEN, buf, len);
HexStrToByte(atwbuf, (unsigned char*)tmpbuf, len + VER_LEN); //strlen(atwbuf)
ret = (uint32_t)crc_check((unsigned char*)tmpbuf, (len + VER_LEN) / 2);
(void)snprintf(crcretbuf, sizeof(crcretbuf), "%04X", (unsigned int)ret);
memcpy(atwbuf + 8, crcretbuf, 4);
return g_flash_op.sota_send((char *)atwbuf, len + VER_LEN);
}` </pre>
2.4 新版本通知
设备收到下载新版本软件包通知后，设备向物联网平台返回应答消息，是否允许设备进行升级。
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
static int32_t sota_new_ver_process(const ota_pcp_head_s *head, const uint8_t *pbuf) {
char ver[VER_LEN];
ota_ver_notify_t *notify = (ota_ver_notify_t *)pbuf;
(void)g_flash_op.get_ver(ver, VER_LEN);
if (strncmp(ver, (const char*)notify->ver, VER_LEN) == 0)
{
SOTA_LOG("Already latest version %s", notify->ver);
sota_send_response_code(MSG_NOTIFY_NEW_VER, DEV_LATEST_VER);
g_at_update_record.state = IDLE;
return SOTA_OK;
}
SOTA_LOG("Notify ver %s,%x, record ver:%s,%x", notify->ver, notify->ver_chk_code,
g_at_update_record.ver,g_at_update_record.ver_chk_code);
if ((strncmp(g_at_update_record.ver, (const char *)notify->ver, VER_LEN) == 0)
&& (notify->ver_chk_code == g_at_update_record.ver_chk_code))
{
SOTA_LOG("state %d, downloaded %d blocks", g_at_update_record.state, g_at_update_record.block_num);
if (g_at_update_record.block_num < g_at_update_record.block_totalnum
&& g_at_update_record.state == DOWNLOADING)
{
sota_send_request_block((char*)notify->ver);
return SOTA_DOWNLOADING;
}
else if (g_at_update_record.block_num == g_at_update_record.block_totalnum
&& g_at_update_record.state == UPDATING)
{
sota_send_response_code(MSG_DOWNLOAD_STATE, DEV_OK);
return SOTA_UPDATING;
}
else if (g_at_update_record.block_num == g_at_update_record.block_totalnum
&& g_at_update_record.state == UPDATED)
{
return SOTA_UPDATED;
}
}
sota_reset_record_info(notify);
sota_send_request_block((char*)notify->ver);
return SOTA_DOWNLOADING;
}` </pre>
2.5 请求分片包
设备向物联网平台请求下载软件包函数
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
static int32_t sota_data_block_process(const ota_pcp_head_s *head, const uint8_t *pbuf) {
uint16_t block_seq = 0;
int ret = SOTA_OK;
if (g_at_update_record.state != DOWNLOADING)
{
return SOTA_UNEXPECT_PACKET;
}
if (*pbuf == UPDATE_TASK_EXIT)
{
g_at_update_record.state = IDLE;
return SOTA_EXIT;
}
block_seq = ((*(pbuf + 1) << 8) & 0XFF00) | (*(pbuf + 2) & 0XFF);
if (g_at_update_record.block_num != block_seq)
{
SOTA_LOG("Download wrong,we need block %X, but rx %X:",(int)g_at_update_record.block_num, (int)block_seq);
return SOTA_UNEXPECT_PACKET;
}
SOTA_LOG("off:%lx size:%x ",g_at_update_record.block_offset,head->data_len);
ret = g_storage_device->write_software(g_storage_device, g_at_update_record.block_offset,(const uint8_t *)(pbuf + BLOCK_HEAD), head->data_len);
if (ret != SOTA_OK)
{
SOTA_LOG("write software failed. ret:%d", ret);
sota_send_response_code(MSG_DOWNLOAD_STATE, DEV_NO_SPACE);
return SOTA_WRITE_FLASH_FAILED;
}
g_at_update_record.block_offset += g_at_update_record.block_size;
g_at_update_record.block_tolen += head->data_len;
g_at_update_record.block_num++;
if ((g_at_update_record.block_num) < g_at_update_record.block_totalnum)
{
SOTA_LOG("Rx total %d bytes downloading\r\n", g_at_update_record.block_tolen);
sota_send_request_block(g_at_update_record.ver);
return SOTA_DOWNLOADING;
}
else
{
SOTA_LOG("Rx total %d bytes, UPDATING...\r\n", g_at_update_record.block_tolen);
ret = g_storage_device->write_software_end(g_storage_device, PACK_DOWNLOAD_OK, g_at_update_record.block_tolen);
if (ret != SOTA_OK)
{
SOTA_LOG("write software end ret:%d", ret);
sota_send_response_code(MSG_DOWNLOAD_STATE, FIRMWARE_CHECK_ERROR);
return SOTA_WRITE_FLASH_FAILED;
}
else
{
g_at_update_record.state = UPDATING;
sota_send_response_code(MSG_DOWNLOAD_STATE, DEV_OK);
return SOTA_UPDATING;
}
}
}` </pre>
2.6 执行升级
设备收到物联网平台下发的执行升级消息后，将对收到消息后的执行动作进行应答
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
static int32_t sota_update_exc_process(const ota_pcp_head_s *head, const uint8_t *pbuf) {
int ret = SOTA_OK;
SOTA_LOG("Begin excute update");
if (g_at_update_record.state != UPDATING)
{
return SOTA_UNEXPECT_PACKET;
}
ret = g_storage_device->active_software(g_storage_device);
if (ret != SOTA_OK)
{
SOTA_LOG("Active software failed ret:%d.", ret);
sota_send_response_code(MSG_EXC_UPDATE, DEV_INNER_ERROR);
return SOTA_WRITE_FLASH_FAILED;
}
else
{
g_at_update_record.state = UPDATED;
(void)flag_write(FLAG_APP, (void*)&g_at_update_record, sizeof(sota_update_info_t));
sota_send_response_code(MSG_EXC_UPDATE, DEV_OK);
return SOTA_UPDATED;
}
}` </pre>
2.7 上报升级结果
设备向物联网平台上报升级结果
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">`/* 公众号：轻松学长 */
static int sota_status_check(void) {
upgrade_state_e state;
char sbuf[64] = {0};
char tmpbuf[VER_LEN+1] = {0};
memset(&g_at_update_record, 0, sizeof(sota_update_info_t));
if (flag_read(FLAG_APP, (char*)&g_at_update_record, sizeof(sota_update_info_t)))
{
SOTA_LOG("flag read err");
return SOTA_FAILED;
}
SOTA_LOG("state:%d flash ver:%s",g_at_update_record.state, g_at_update_record.ver);
if (g_flash_op.firmware_download_stage == BOOTLOADER
&& g_flash_op.current_run_stage == BOOTLOADER)
{
if (g_at_update_record.state == DOWNLOADING)
{
sota_send_request_block(g_at_update_record.ver);
return SOTA_DOWNLOADING;
}
}
else
{
(void)flag_upgrade_get_result(&state);
SOTA_LOG("upgrade result: %d", state);
if (state == OTA_SUCCEED)
{
SOTA_LOG("Update version %s success", g_at_update_record.ver);
memcpy(tmpbuf + 1, g_at_update_record.ver, VER_LEN);
(void)ver_to_hex(tmpbuf, VER_LEN+1, sbuf);
(void)sota_at_send(MSG_NOTIFY_STATE, sbuf, (VER_LEN+1) * 2);
}
}
memset(&g_at_update_record, 0, sizeof(sota_update_info_t));
(void)flag_write(FLAG_APP, (const void*)&g_at_update_record, sizeof(sota_update_info_t));
return SOTA_OK;
}` </pre>
2.8 超时处理
请求升级包或升级时设备超时处理
<pre class="custom" data-tool="mdnice编辑器" style="margin-top: 10px; margin-bottom: 10px; border-radius: 5px; box-shadow: rgba(0, 0, 0, 0.55) 0px 2px 10px;">/* 公众号：轻松学长 */ void sota_timeout_handler(void) { if (g_at_update_record.state == DOWNLOADING) { SOTA_LOG("Download block %d over time", g_at_update_record.block_num); sota_send_response_code(MSG_EXC_UPDATE, DOWNLOAD_TIME_OUT); sota_send_request_block(g_at_update_record.ver); } else if (g_at_update_record.state == UPDATING) { SOTA_LOG("Download finish. excute over time"); sota_send_response_code(MSG_EXC_UPDATE, DOWNLOAD_TIME_OUT); sota_send_response_code(MSG_DOWNLOAD_STATE, DEV_OK); } } </pre>
3、踩坑记录
电信AEP平台流量限制：对于NB-IOT通信设备，平台限制5分钟只允许300条交互，包含设备请求、平台下发内容，设备回复ACK，设备注册，设备订阅等。
电信AEP平台只允许三台设备同时升级，除该三台设备之外其他设备处于排队状态，待该三台设备升级完成后，才开始下一批设备升级
升级包大小2M以内，升级时按软件包中设置值分片，默认500字节
升级包需打包为.zip类型的文件
电信AEP平台目前仅支持LWM2M协议的设备升级
到这里，基于电信AEP平台的NB-IOT远程升级系列就结束啦
若有需要完整源码，工众号回复 OTA 自取哦
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