I am trying to log some data from analog input to sd card. I am using tmp36 sensor, but I am only getting -50 degrees. Normally I get this value when I unplug 5v cable so I checked 5v pin but it works normally.
// Include libraries
#include <SPI.h>
#include <Ethernet.h>
#include <Time.h>
#include <TimeLib.h>
#include <SD.h>
// temp sensor consts
const unsigned int TEMP_SENSOR_PIN = 1;
const unsigned int SUPPLY_VOLTAGE = 5;
const unsigned int BAUD_RATE = 9600;
byte mac [] = { 0x90, 0xA2, 0xDA, 0x0E, 0xFE, 0x40 };
// Chip select pin
const int chipSelect = 4;
// NTP Server
IPAddress timeServer(129, 6, 15, 28);
const int timeZone = 1;
// Create UDP server
EthernetUDP Udp;
unsigned int localPort = 8888;
void setup() {
// Open serial communications
Serial.begin(BAUD_RATE);
// disabling sd card
pinMode(4, OUTPUT);
digitalWrite(4, HIGH);
// Start Ethernet
if (Ethernet.begin(mac) == 0) {
// no point in carrying on, so do nothing forevermore:
while (1) {
Serial.println("Failed to configure Ethernet using DHCP");
delay(10000);
}
}
// Init SD card
Serial.print("Initializing SD card...");
pinMode(10, OUTPUT);
if (!SD.begin(chipSelect)) {
Serial.println("Card failed, or not present");
// don't do anything more:
return;
}
Serial.println("card initialized.");
// Print server info
Serial.print("IP number assigned by DHCP is ");
Serial.println(Ethernet.localIP());
Udp.begin(localPort);
Serial.println("waiting for sync");
setSyncProvider(getNtpTime);
}
void loop() {
// Measure the temperature
const int sensor_voltage = analogRead(TEMP_SENSOR_PIN);
const float voltage = sensor_voltage * SUPPLY_VOLTAGE / 1024;
float t = (voltage * 1000 - 500) / 10;
// Transform to String
String temp = String((int) t);
// Format time
String log_time = String(day()) + "/" +
String(month()) + "/" + String(year()) + " " +
String(hour()) + ":" + String(minute()) + ":" +
String(second());
// Make a string for assembling the data to log
String dataString = log_time + "," + temp ;
// Open file
File dataFile = SD.open("datalog.txt", FILE_WRITE);
// Write data to file
if (dataFile) {
dataFile.println(dataString);
dataFile.close();
Serial.println(dataString);
}
else {
Serial.println("error opening datalog.txt");
}
// Repeat every 10 seconds
delay(10000);
}
const int NTP_PACKET_SIZE = 48; // NTP time is in the first 48 bytes of message
byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming & outgoing packets
time_t getNtpTime()
{
while (Udp.parsePacket() > 0) ; // discard any previously received packets
Serial.println("Transmit NTP Request");
sendNTPpacket(timeServer);
uint32_t beginWait = millis();
while (millis() - beginWait < 1500) {
int size = Udp.parsePacket();
if (size >= NTP_PACKET_SIZE) {
Serial.println("Receive NTP Response");
Udp.read(packetBuffer, NTP_PACKET_SIZE); // read packet into the buffer
unsigned long secsSince1900;
// convert four bytes starting at location 40 to a long integer
secsSince1900 = (unsigned long)packetBuffer[40] << 24;
secsSince1900 |= (unsigned long)packetBuffer[41] << 16;
secsSince1900 |= (unsigned long)packetBuffer[42] << 8;
secsSince1900 |= (unsigned long)packetBuffer[43];
return secsSince1900 - 2208988800UL + timeZone * SECS_PER_HOUR;
}
}
Serial.println("No NTP Response :-(");
return 0; // return 0 if unable to get the time
}
// send an NTP request to the time server at the given address
void sendNTPpacket(IPAddress &address)
{
// set all bytes in the buffer to 0
memset(packetBuffer, 0, NTP_PACKET_SIZE);
// Initialize values needed to form NTP request
// (see URL above for details on the packets)
packetBuffer[0] = 0b11100011; // LI, Version, Mode
packetBuffer[1] = 0; // Stratum, or type of clock
packetBuffer[2] = 6; // Polling Interval
packetBuffer[3] = 0xEC; // Peer Clock Precision
// 8 bytes of zero for Root Delay & Root Dispersion
packetBuffer[12] = 49;
packetBuffer[13] = 0x4E;
packetBuffer[14] = 49;
packetBuffer[15] = 52;
// all NTP fields have been given values, now
// you can send a packet requesting a timestamp:
Udp.beginPacket(address, 123); //NTP requests are to port 123
Udp.write(packetBuffer, NTP_PACKET_SIZE);
Udp.endPacket();
}