I am successfully using a BMP280 sensor via SPI connection with an Arduino Uno R3 board. I'm trying to run the same code with the same setup on an Arduino Ethernet. However the sensor is not initializing.
The setup function looks as follows:
void setup() {
delay(1000);
dht.begin(); // starts DHT sensor
chk = dht.read(DHTPIN); // reads DHT status
while ((!bmp.begin()) || (chk != 1) ) {
// checks DHT and BMP status and shows red LED, in case one of them
// wasn't found. Loops and resets timeout each time.
wdt_reset();
Serial.println("Could not find a valid sensor, check wiring!");
digitalWrite(RED, HIGH);
delay(300);
digitalWrite(RED, LOW);
delay(1000);
chk = dht.read(DHTPIN);
}
}
The code only returns the error message and does not initialize the BMP sensor (DHT is fine).
Full code:
#include "ThingSpeak.h"
#include <SPI.h>
#include <DHT.h>
#include <Ethernet.h>
byte mac[] = { 0x90, 0xA2, 0xDA, 0x00, 0xE5, 0xBF};
IPAddress ip(10,42,0,69);
EthernetClient client;
// --- Libraries --- //
#include <avr/wdt.h> // Watchdog, interrupts and reboots
#include <Adafruit_BMP280.h> // BMP library for BMP280
// --- Constants --- //
// DHT22
#define DHTPIN 7
// BMP280 (SPI)
#define BMP_SCK 13 // Serial clock pin for BMP (10k pullup to +5V)
#define BMP_MISO 12 // SDO, has 10k pullup
#define BMP_MOSI 11 // SDI, no pullup
#define BMP_CS 9 // CS, has 10k pullup
// LEDs
#define RED 5 // pin for LEDs
#define YELLOW 3
#define GREEN 2
unsigned long myChannelNumber = 115634;
const char * myWriteAPIKey = "***"; // removed for privacy reasons
float dht_temp;
float dht_hum;
float bmp_temp; // values from sensors
float bmp_press;
int chk; // DHT status (0 or 1)
int k; // counter variable
int number;
char COLOR;
// --- Initialization --- //
DHT dht(DHTPIN, DHT22); // initializes sensors
Adafruit_BMP280 bmp(BMP_CS, BMP_MOSI, BMP_MISO, BMP_SCK);
void setup() {
wdt_disable(); // disables watchdog for initial communication
pinMode(10, OUTPUT);
digitalWrite(10, HIGH);
pinMode(4, OUTPUT);
digitalWrite(4, HIGH);
pinMode(YELLOW, OUTPUT); // LED pins set as output
pinMode(RED, OUTPUT);
digitalWrite(YELLOW, HIGH); // starts yellow LED
Serial.begin(9600); // begin serial connection with 9600 baud
delay(500); // delay to get connection and sensors ready
wdt_enable(WDTO_8S); // start watchdog timeout (4 sec might be too short)
blink(RED, 3);
Serial.println(bmp.begin());
dht.begin(); // starts DHT sensor
chk = dht.read(DHTPIN); // reads DHT status
if ((!bmp.begin()) || (chk != 1) ) {
// checks DHT and BMP status and shows red LED, in case one of them
// wasn't found. Loops and resets timeout each time.
wdt_reset();
Serial.println("Could not find a valid sensor, check wiring!");
digitalWrite(RED, HIGH);
delay(300);
digitalWrite(RED, LOW);
delay(1000);
chk = dht.read(DHTPIN);
}
Ethernet.begin(mac, ip);
ThingSpeak.begin(client);
}
// --- Loop --- //
void loop() {
wdt_reset(); // resets watchdog
pinMode(GREEN, OUTPUT); // gets green LED ready
digitalWrite(GREEN, LOW);
delay(1600); // delay for sensors to be read. In total, at least 2 sec!
dhtread();
delay(5000);
wdt_reset();
bmpread();
ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);
delay(5000);
wdt_reset();
delay(5000);
}
void blink(char COLOR, int number) {
for (k = 1; k <= number; k = k + 1) {
// blinks 3x to show that Arduino rebooted
digitalWrite(COLOR, HIGH);
delay(100);
digitalWrite(COLOR, LOW);
delay(100);
}
}
void bmpread() {
bmp_temp = bmp.readTemperature(); // reads BMP sensor
bmp_press = bmp.readPressure();
Serial.println(bmp_temp);
Serial.println(bmp_press);
if (bmp_press > 0.0) {
// if sensor isn't attached, it shows 0.0 or negative pressure.
// This is used as check criterion
digitalWrite(GREEN, HIGH); // blinks green for good BMP values
Serial.println("bmp ok");
ThingSpeak.setField(3,bmp_temp);
ThingSpeak.setField(4,bmp_press);
delay(150);
digitalWrite(GREEN, LOW);
} else {
// if pressure is 0.0 or negative, blink red
// and print 0.0 to keep formatting
digitalWrite(RED, HIGH);
Serial.println("Error, BMP280 missing");
delay(150);
digitalWrite(RED, LOW);
}
}
void dhtread() {
chk = dht.read(DHTPIN); // checks if connection to DHT sensor is ok (0: no connection, 1: ok)
if (chk == 1) {
dht_temp = dht.readTemperature();
dht_hum = dht.readHumidity(); // reads DHT sensor
digitalWrite(GREEN, HIGH); // blinks once for successful DHT sensor values
ThingSpeak.setField(1,dht_temp);
ThingSpeak.setField(2,dht_hum);
delay(150);
digitalWrite(GREEN, LOW);
delay(100);
} else {
// if no connection, blink red instead and print "nan"
// (keeps formatting ok)
digitalWrite(RED, HIGH);
Serial.print("Error, DHT22 missing");
delay(150);
digitalWrite(RED, LOW);
delay(100);
}
}
The problem now is that it seems to initialize (bmp.begin() returns 1), but the sensor is still not reading a correct value (either 0.0 for both pressure and temperature, or a large negative pressure and very large temperature (-2602 Pa, 185°C). What might be the problem? I have tried it with another sensor of the same type, same result. Where else can I attach the CS wire to?
