[英]Send data over BLE with RFDuino
I've attached sensor to RFDuino and want to send readings over BLE to Android app. 我已将传感器连接到RFDuino,并希望通过BLE将读数发送到Android应用。
const int sensorPin = 2;
int sensorValue = 0;
void setup() {
Serial.begin(9600);
RFduinoBLE.begin();
}
void loop() {
sensorValue = analogRead(sensorPin);
float voltage= sensorValue * (3.3 / 1023.0);
Serial.print("uv sensor = ");
Serial.println(voltage);
RFduinoBLE.sendFloat(voltage);
delay(1000);
}
In console I see values like 0.2
. 在控制台中,我看到类似
0.2
值。 But in app it translates to something like 00-00-A4-41
It's described here but I don't get what's the logic behind it. 但是在应用程序中,它翻译为
00-00-A4-41
之类00-00-A4-41
虽然在此进行了描述,但我不明白其背后的逻辑是什么。 How do I properly convert the value sent from RFDuino? 如何正确转换从RFDuino发送的值?
RFduino sends floats in little endian. RFduino发送小尾数形式的浮点数。 Your android app will receive it as 4 bytes and you will need to convert it to big endian by reversing the order of the bytes (and converting to float).
您的android应用将以4个字节的形式接收它,您需要通过反转字节顺序(并将其转换为float)将其转换为big endian。 There's several threads on the topic, eg.
例如,该主题有多个主题。 Converting Little Endian to Big Endian and the one you used.
将Little Endian转换为Big Endian以及您使用的那个。
It should just be a quick read up on endianness and floating point format to understand the logic behind it. 应该只是快速了解字节序和浮点格式,以了解其背后的逻辑。 But basically, the 4 byte float has the bytes stored in reverse order of each other in little vs. big endian.
但基本上,4字节浮点型的字节以小尾数与大尾数相反的顺序存储。 When you reverse the 4 bytes in little endian then it becomes big endian and you're good to go for your situation.
当您以Little Endian反转4个字节时,它将变成Big Endian,您可以根据情况进行选择。
http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Data/endian.html http://en.wikipedia.org/wiki/Single-precision_floating-point_format http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Data/endian.html http://en.wikipedia.org/wiki/Single-precision_floating-point_format
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