RFM69W build-in temperature sensor "werid" reading

[xujianningkp]

I'm trying to send the rfm69w build-in temperature reading to other. Whenever I printed the the temperature, the serial monitor shown ***** before each reading. Any one know how to avoid it?

*****82.40
*****84.20
*****82.40
*****82.40
*****82.40
*****82.40

Code Select Expand

#include <RFM69.h>
#include <SPI.h>
#include <SPIFlash.h>

#define NODEID      99
#define NETWORKID   100
#define GATEWAYID   1
#define FREQUENCY   RF69_915MHZ //Match this with the version of your Moteino! (others: RF69_433MHZ, RF69_868MHZ)
#define KEY         "thisIsEncryptKey" //has to be same 16 characters/bytes on all nodes, not more not less!
#define LED         9
#define SERIAL_BAUD 115200
#define ACK_TIME    30  // # of ms to wait for an ack

int TRANSMITPERIOD = 10000; //transmit a packet to gateway so often (in ms)
byte sendSize=0;
boolean requestACK = false;
SPIFlash flash(8, 0xEF30); //EF40 for 16mbit windbond chip
RFM69 radio;

typedef struct {		
  float         temp1;   //temperature maybe?
  float         temp2;
  float         temp3;
} Payload;
Payload theData;

void setup() {
  Serial.begin(SERIAL_BAUD);
  radio.initialize(FREQUENCY,NODEID,NETWORKID);
  //radio.setHighPower(); //uncomment only for RFM69HW!
  radio.encrypt(KEY);
  char buff[50];
  sprintf(buff, "\nTransmitting at %d Mhz...", FREQUENCY==RF69_433MHZ ? 433 : FREQUENCY==RF69_868MHZ ? 868 : 915);
  //Serial.println(buff);
}

long lastPeriod = -1;
void loop() {
  
  int currPeriod = millis()/TRANSMITPERIOD;
  if (currPeriod != lastPeriod)
  {
    byte temperature =  radio.readTemperature(-1); // -1 = user cal factor, adjust for correct ambient
    theData.temp1 = 1.8 * temperature + 32; // 9/5=1.8
    Serial.println(theData.temp1);
    

    if (radio.sendWithRetry(GATEWAYID, (const void*)(&theData), sizeof(theData)))

    Serial.println();
    Blink(LED,3);
    lastPeriod=currPeriod;

  }
  
}

void Blink(byte PIN, int DELAY_MS)
{
  pinMode(PIN, OUTPUT);
  digitalWrite(PIN,HIGH);
  delay(DELAY_MS);
  digitalWrite(PIN,LOW);
}

[Felix]

It's coming from the library - https://github.com/LowPowerLab/RFM69/blob/master/RFM69.cpp

Line 417:

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while ((readReg(REG_TEMP1) & RF_TEMP1_MEAS_RUNNING)) Serial.print('*');

[xujianningkp]

Whenever the temperature is below 32F, the build-in temp sensor is reading some weird numbers like 475, 498........ Have any idea what's wrong with it? thanks