用W5100控制LED的时候，总是会有个闪烁/闪断
本帖最后由 Stormer 于 2017-8-10 07:01 编辑我用的是IDE里的SAMPLE代码---WebClientRepeating。
代码的目的就是不断刷新读取指定网页的内容，然后根据内容控制LED是点亮还是关闭。
目标网页的内容只有一个字符 1 ，表示打开LED。
然而每当再次请求的时候（httpRequest()），LED会熄灭一下，这不是我想要的效果。我需要这个LED在网页内容为0的时候才会熄灭。
LED只是一个最简单的测试，闪烁一下还不要紧，但如果以后变成其他设备的时候情况肯定会变得很诡异不正常。
下面是代码。
#include <SPI.h>
#include <Ethernet.h>
// assign a MAC address for the ethernet controller.
// fill in your address here:
byte mac[] = {
0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
// fill in an available IP address on your network here,
// for manual configuration:
IPAddress ip(192, 168, 0, 177);
// fill in your Domain Name Server address here:
//IPAddress myDns(1, 1, 1, 1);
// initialize the library instance:
EthernetClient client;
char server[] = "www.anjinkeji.com";
//IPAddress server(64,131,82,241);
#define LED_OUT 2
int lightState = 0; //LED开启状态
bool isConnection = true;
unsigned long lastConnectionTime = 0; // last time you connected to the server, in milliseconds
//const unsigned long postingInterval = 10L * 1000L; // delay between updates, in milliseconds
const unsigned long postingInterval = 2L * 1000L;
// the "L" is needed to use long type numbers
void setup() {
// start serial port:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
// give the ethernet module time to boot up:
delay(1000);
// start the Ethernet connection using a fixed IP address and DNS server:
Ethernet.begin(mac, ip);
// print the Ethernet board/shield's IP address:
Serial.print("My IP address: ");
Serial.println(Ethernet.localIP());
}
void loop()
{
// if there's incoming data from the net connection.
// send it out the serial port.This is for debugging
// purposes only:
if (client.available() )
{
char c = client.read();
Serial.write(c);
if (c == '1')
{
digitalWrite(LED_OUT, HIGH);
}
else
{
if (c == '0')
{
digitalWrite(LED_OUT, LOW);
}
}
}
// if ten seconds have passed since your last connection,
// then connect again and send data:
if (millis() - lastConnectionTime > postingInterval)
{
httpRequest();
}
}
// this method makes a HTTP connection to the server:
void httpRequest()
{
// close any connection before send a new request.
// This will free the socket on the WiFi shield
client.stop();
// if there's a successful connection:
if (client.connect(server, 80)) {
Serial.println("connecting...");
// send the HTTP GET request:
client.println("GET /t.html HTTP/1.1");
client.println("Host: www.anjinkeji.com");
// client.println("User-Agent: arduino-ethernet");
client.println("Connection: close");
client.println();
// note the time that the connection was made:
lastConnectionTime = millis();
} else {
// if you couldn't make a connection:
Serial.println("connection failed");
}
}
串行监视器：
My IP address: 192.168.0.177
connecting...
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:16 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1connecting...
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:18 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1connecting...
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:20 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1connecting...
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:22 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1connecting...
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:25 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1connecting...
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:27 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1 没用过，说下我的猜测。
1、IO没有设置成输出模式，需要初始化一个状态。
2、0可能来自某个函数无返回时的输出，建议换个其他值试试，比如2。 本帖最后由 Stormer 于 2017-8-11 05:07 编辑
通幽境 发表于 2017-8-11 02:06
没用过，说下我的猜测。
1、IO没有设置成输出模式，需要初始化一个状态。
2、0可能来自某个函数无返回时 ...
谢谢，我居然忘了加pinMode哈哈。
1、setup()中加入了pinMode(LED_OUT, OUTPUT);
2、设置LED状态为LOW的判断改成了2，if (c == '2')
问题依旧。LED还是在从新请求网络的时候闪烁一下。我再找找原因。
-----------------------
问题解决了。
问题在于网络请求的结果不仅仅是网页里的HTML内容，还包括了反馈给浏览器的信息。
client.read() 逐字读出的内容是：
HTTP/1.1 200 OK
Server: nginx
Date: Wed, 09 Aug 2017 22:52:20 GMT
Content-Type: text/html
Content-Length: 1
Last-Modified: Wed, 09 Aug 2017 22:33:30 GMT
Connection: close
ETag: "598b8dba-1"
Accept-Ranges: bytes
1
所以结果就很明显不正常了。
改了下代码现在只把 client.read() 里最后一位的内容读出来作为判断就可以了。
void loop()
{
if (client.available() )
{
cResult = client.read();
Serial.write(cResult);
}
// if 2 seconds have passed since your last connection,
// then connect again and send data:
if (millis() - lastConnectionTime > postingInterval)
{
//Serial.println(c);
switch (cResult)
{
case'0':
digitalWrite(LED_OUT, LOW);
lightState = 0;
break;
case'1':
if (lightState == 0)
{
digitalWrite(LED_OUT, HIGH);
lightState = 1;
}
break;
}
httpRequest();
}
}
Stormer 发表于 2017-8-11 02:58
谢谢，我居然忘了加pinMode哈哈。
1、setup()中加入了pinMode(LED_OUT, OUTPUT);
学习了。。
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