如何在内存有限的嵌入式系统上使用 AT 读取短信? [英] How to read SMS using AT on an embedded system with limited memory?
问题描述
我正在开发一款嵌入式软件，该软件还通过 AT 协议与调制解调器进行通信.现在我想阅读消息，但我的内存容量出现问题.可能是有多个消息给我，并且使用 AT 命令集，我将它们一次全部返回.我没有足够的内存来存储它们来处理它们(我只有 1KB 左右).
请参阅此处的示例:http://www.smssolutions.net/tutorials/gsm/receivesmsat/
我发送AT+CMGL="ALL".然后我会得到类似的东西:
+CMGL: 1,"REC UNREAD","+31625012354",,"07/07/05,09:55:16+08"测试消息 1+CMGL: 2,"REC UNREAD","+31625012354",,"07/07/05,09:56:03+08"测试消息2好的这里的问题是消息可能包含某些指令，这些指令会触发某些操作，这些操作可能需要一段时间才能执行.在此期间，用于从调制解调器接收数据的缓冲区可能(将)溢出.另一方面，我没有内存容量先将所有消息读入内存以防止缓冲区溢出，然后从内存中处理它们.
另一种方法是使用 AT+CMGR=2 读取一条消息，只返回一条消息:
+CMGL: 2,"REC UNREAD","+31625012354",,"07/07/05,09:56:03+08"测试消息2好的但是，要使其正常工作，我需要知道存储位置(在上面的示例中为 2).
直觉告诉我先运行AT+CMGL，解析数据，只保留存储位置，然后用AT+一一请求解析(删除)CMGR.
但是，我想获得第二意见.我对 AT 和嵌入式软件还没有那么熟悉，所以也许我忽略了一些东西.
发送 AT+CMGL="ALL" 并保存第一条消息直到返回.忽略所有其他数据，直到您收到 OK，表明调制解调器已完成.处理完第一条消息后，通过发送AT+CMGD=(其中是第一条消息的编号)将其删除.重复.
是的，它有点丑，但效果很好.
I'm developing a piece of embedded software, which also communicates with a modem through the AT protocol. Now I want to read messages, but I have come across a problem with my memory capacity. It could be that there are multiple messages for me, and using the AT command set, I get them returned all at once. I do not have the memory capacity to store them all to process them (I only have 1KB or so).
See the examples here: http://www.smssolutions.net/tutorials/gsm/receivesmsat/
I send AT+CMGL="ALL". I then get back something like:
+CMGL: 1,"REC UNREAD","+31625012354",,"07/07/05,09:55:16+08"
Test message 1
+CMGL: 2,"REC UNREAD","+31625012354",,"07/07/05,09:56:03+08"
Test message 2
OK
The problem here is that the message can contain certain directives, which trigger certain actions, which might take a while to execute. During that time, the buffer for receiving data from the modem can (will) overflow. On the other hand, I do not have the memory capacity to first read ALL the messages into memory to prevent the buffer overflow, and then process them from memory.
An alternative is reading a single message, with AT+CMGR=2, getting back just one message:
+CMGL: 2,"REC UNREAD","+31625012354",,"07/07/05,09:56:03+08"
Test message 2
OK
However, for this to work, I need know the storage location (2 in the above example).
My gut feeling tells me to first run AT+CMGL, parsing the data and only keeping the storage locations, then requesting and parsing (and deleting) them one by one with AT+CMGR.
However, I would like to receive a second opinion. I'm not that experienced with AT nor with embedded software yet, so perhaps I'm overlooking something.
Send AT+CMGL="ALL" and save the first message up to the return. Ignore all other data until you receive OK, indicating that the modem is done. After processing the first message, delete it by sending AT+CMGD=<NUM> (where is the number of the first message). Repeat.
Yes, it's kind of ugly, but it works fine.
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