如何使用Python从UART Beaglebone获取数据输出

Question

i'm working on little project to make weather station and collect the data using Python programming. I'm using this weather station click here.

The problem is, that weather station is only providing sample code using C programming, i'm not good with that. So i decide to using Python, but the data output format is like this

c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040
c000s000g000t084r000p000h63b10040

I'm using minicom to see the output. I'm not understand how the code sample in their website works, so if you can give me explanation or some example how it works and convert it to Python programming, that will be great.

This is their sample code written with C

        char                 databuffer[35];
        double               temp;

        void getBuffer()                                                                    //Get weather status data
        {
          int index;
          for (index = 0;index < 35;index ++)
          {
            if(Serial.available())
            {
              databuffer[index] = Serial.read();
              if (databuffer[0] != 'c')
              {
                index = -1;
              }
            }
            else
            {
              index --;
            }
          }
        }

        int transCharToInt(char *_buffer,int _start,int _stop)                               //char to int）
        {
          int _index;
          int result = 0;
          int num = _stop - _start + 1;
          int _temp[num];
          for (_index = _start;_index <= _stop;_index ++)
          {
            _temp[_index - _start] = _buffer[_index] - '0';
            result = 10*result + _temp[_index - _start];
          }
          return result;
        }

        int WindDirection()                                                                  //Wind Direction
        {
          return transCharToInt(databuffer,1,3);
        }

        float WindSpeedAverage()                                                             //air Speed (1 minute)
        {
          temp = 0.44704 * transCharToInt(databuffer,5,7);
          return temp;
        }

        float WindSpeedMax()                                                                 //Max air speed (5 minutes)
        {
          temp = 0.44704 * transCharToInt(databuffer,9,11);
          return temp;
        }

        float Temperature()                                                                  //Temperature ("C")
        {
          temp = (transCharToInt(databuffer,13,15) - 32.00) * 5.00 / 9.00;
          return temp;
        }

        float RainfallOneHour()                                                              //Rainfall (1 hour)
        {
          temp = transCharToInt(databuffer,17,19) * 25.40 * 0.01;
          return temp;
        }

        float RainfallOneDay()                                                               //Rainfall (24 hours)
        {
          temp = transCharToInt(databuffer,21,23) * 25.40 * 0.01;
          return temp;
        }

        int Humidity()                                                                       //Humidity
        {
          return transCharToInt(databuffer,25,26);
        }

        float BarPressure()                                                                  //Barometric Pressure
        {
          temp = transCharToInt(databuffer,28,32);
          return temp / 10.00;
        }

        void setup()
        {
          Serial.begin(9600);
        }
        void loop()
        { 
          getBuffer();                                                                      //Begin!
          Serial.print("Wind Direction: ");
          Serial.print(WindDirection());
          Serial.println("  ");
          Serial.print("Average Wind Speed (One Minute): ");
          Serial.print(WindSpeedAverage());
          Serial.println("m/s  ");
          Serial.print("Max Wind Speed (Five Minutes): ");
          Serial.print(WindSpeedMax());
          Serial.println("m/s");
          Serial.print("Rain Fall (One Hour): ");
          Serial.print(RainfallOneHour());
          Serial.println("mm  ");
          Serial.print("Rain Fall (24 Hour): ");
          Serial.print(RainfallOneDay());
          Serial.println("mm");
          Serial.print("Temperature: ");
          Serial.print(Temperature());
          Serial.println("C  ");
          Serial.print("Humidity: ");
          Serial.print(Humidity());
          Serial.println("%  ");
          Serial.print("Barometric Pressure: ");
          Serial.print(BarPressure());
          Serial.println("hPa");
          Serial.println("");
           Serial.println("");
        }

Thank you.

Answer 1

You have to "decode" the data format as suggested in the manual (It outputs 37 bytes per second, including the end CR/LF):

c000：air direction, degree
s000：air speed(1 minute), 0.1 miles per hour
g000：air speed(5 minutes), 0.1 miles per hour
t086：temperature, Fahrenheit
r000：rainfall(1 hour), 0.01 inches
p000：rainfall(24 hours), 0.01 inches
h53：humidity,% (00％= 100)
b10020：atmosphere,0.1 hpa

For example if you have the input line:

c000s000g000t084r000p000h63b10040

Then to get the air direction [degree] in c (The example above):

int WindDirection() //Wind Direction
    {
      return transCharToInt(databuffer,1,3);
    }

And in Python:

def win_direction():
    return int(dataBuffer[1,3])

You now need to pass threw all the 8 parts of the data structure and build a function that will extract the data and convert it to meaningful number if needed.