我使用的是NodeMCU(ESP8266)和Arduino的IDE。草图一部分工作,我能看到的串行显示器上模拟解读,因为我动了锅。
Web服务器的index.html是在SPIFFs文件系统。 当连接和服务器加载我可以看到浏览器上的压力表,但不显示从针运动。
我的目标是让ADC读数和更新仪表针。 这是我到目前为止,这是从https://rawgit.com/Mikhus/canvas-gauges/master/examples/issue-63.html样本
怎样才可以修改,以获得ADC读数?
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Gauge Test</title>
<script src="../gauge.min.js"></script>
<style>body {
padding: 20px;
margin: 0;
background: #fff
}</style>
</head>
<body>
<a href="#" onclick="gaugePS.value=570">570</a>
<a href="#" onclick="gaugePS.value=583">583</a>
<a href="#" onclick="gaugePS.value=830">830</a>
<hr>
<canvas id="gauge-ps"></canvas>
<script>
var gaugePS = new RadialGauge({
renderTo: 'gauge-ps',
width: 400,
height: 400,
units: 'PS',
minValue: 0,
maxValue: 1000,
majorTicks: [
'0','100','200','300','400','500','600','700','800','900','1000'
],
minorTicks: 2,
ticksAngle: 270,
startAngle: 45,
strokeTicks: true,
highlights : [
{ from : 457, to : 880, color : 'rgba(78, 78, 76, 0.5)' },
{ from : 880, to : 1000, color : 'rgba(225, 7, 23, 0.75)' }
],
valueInt: 1,
valueDec: 0,
colorPlate: "#fff",
colorMajorTicks: "#686868",
colorMinorTicks: "#686868",
colorTitle: "#000",
colorUnits: "#000",
colorNumbers: "#686868",
valueBox: true,
colorValueText: "#000",
colorValueBoxRect: "#fff",
colorValueBoxRectEnd: "#fff",
colorValueBoxBackground: "#fff",
colorValueBoxShadow: false,
colorValueTextShadow: false,
colorNeedleShadowUp: true,
colorNeedleShadowDown: false,
colorNeedle: "rgba(200, 50, 50, .75)",
colorNeedleEnd: "rgba(200, 50, 50, .75)",
colorNeedleCircleOuter: "rgba(200, 200, 200, 1)",
colorNeedleCircleOuterEnd: "rgba(200, 200, 200, 1)",
borderShadowWidth: 0,
borders: true,
borderInnerWidth: 0,
borderMiddleWidth: 0,
borderOuterWidth: 5,
colorBorderOuter: "#fafafa",
colorBorderOuterEnd: "#cdcdcd",
needleType: "arrow",
needleWidth: 2,
needleCircleSize: 7,
needleCircleOuter: true,
needleCircleInner: false,
animationDuration: 1500,
animationRule: "dequint",
fontNumbers: "Verdana",
fontTitle: "Verdana",
fontUnits: "Verdana",
fontValue: "Led",
fontValueStyle: 'italic',
fontNumbersSize: 20,
fontNumbersStyle: 'italic',
fontNumbersWeight: 'bold',
fontTitleSize: 24,
fontUnitsSize: 22,
fontValueSize: 50,
animatedValue: true
});
gaugePS.draw();
gaugePS.value = "510";
</script>
</body>
</html>
该NodeMCU是服务了一个HTML文件到浏览器。然后,浏览器需要一种机制来从NodeMCU获得最新的值。
有两个部分来实现这一目标:
该HTTP端点将使用最新的阅读浏览器的响应。
首先添加的路由/ps
的处理程序:
// declare handlePsPath before this snippet
server.on("/ps", handlePsPath);
然后实现处理程序:
void handlePsPath()
{
auto requestMethod = server.method();
if (requestMethod == HTTP_GET)
{
auto psValue = getValue();
String psJson = String("{ \"ps\": ") + String(psValue) + String(" }");
server.send(200, "application/json", psJson);
}
}
这是假设你实现getValue()
函数来获取读数。
例如一个例子函数读取A3管脚:
int getValue()
{
return analogRead(A3);
}
添加一个函数来获取读数从上面添加通过将以下在HTML文件中的脚本块端点:
function handlePsValue() {
var json = JSON.parse(this.responseText);
gaugePS.value = json.ps;
}
function updatePsValue() {
var request = new XMLHttpRequest();
request.addEventListener("load", handlePsValue);
request.open("GET", "/ps");
request.send();
}
然后在页面调用这个函数。最平凡的方式做到这一点是添加一个按钮来调用updatePsValue()
页面:
<button onClick="updatePsValue()">Update</button>
另外,浏览器可以轮询使用脚本块一些JavaScript的更新:
// poll for updates once per second
setInterval(updatePsValue, 1000);