Current progress of SPI communcation due to APC0834

components/src/main/java/com/opensourcewithslu/components/controllers/ThermistorController.java

@@ -15,23 +15,26 @@ public class ThermistorController {
 
     // Inject Pi4J Context and digital pins for the thermistor
     @Inject
-    public ThermistorController(
-            Context pi4jContext,
-            @Named("thermistor-input") DigitalInput sensorInput) {
+    public ThermistorController(Context pi4jContext) {
 
         // Initialize the ThermistorHelper with SPI configuration
-        this.thermistorHelper = new ThermistorHelper(pi4jContext, sensorInput);
+        this.thermistorHelper = new ThermistorHelper(pi4jContext);
     }
 
     // Endpoint to get temperature in Celsius
     @Get("/temperature/celsius")
     public double getTemperatureCelsius() {
-        return thermistorHelper.getTemperatureCelsius();
+        return thermistorHelper.getTemperatureInCelsius();
     }
 
     // Endpoint to get temperature in Fahrenheit
     @Get("/temperature/fahrenheit")
     public double getTemperatureFahrenheit() {
-        return thermistorHelper.getTemperatureFahrenheit();
+        return thermistorHelper.getTemperatureInFahrenheit();
     }
-}
+
+    @Get("/rawValue")
+    public double readADCValue(){
+        return thermistorHelper.readADCValue();
+    }
+}

components/src/main/resources/application.yml

@@ -10,6 +10,11 @@ pi4j:
       address: 8            # <3>
       baud: 500000          # <4>
       reset-pin: 25         # <5>
+    thermistor-adc: # Configuration for Thermistor ADC
+      name: Thermistor ADC  # <1>
+      address: 17            # <2> # SPI channel 0
+      baud: 1000000         # <3> # 1 MHz SPI clock speed
+      mode: SPI_MODE_0
   # end::spi[]
 
   # tag::pwm[]
@@ -133,12 +138,6 @@ pi4j:
       pulses-per-revolution: 20    # <3>
       provider: pigpio-digital-input # <4>
       debounce: 500                # <5>
-    thermistor-input:
-      name: Thermistor Input
-      address: 18
-      provider: pigpio-digital-input
-      pull: PULL_DOWN
-      debounce: 2000
   # end::digitalInput[]
 
   # tag::digitalOutput[]
@@ -167,12 +166,6 @@ pi4j:
       shutdown: LOW
       initial: LOW
       provider: pigpio-digital-output
-    thermistor-output:
-      name: Thermistor Output
-      address: 18
-      provider: pigpio-digital-output
-      initial: LOW
-      shutdown: LOW
   # end::digitalOutput[]
 
   # tag::multiInput[]

pi4micronaut-utils/src/main/java/com/opensourcewithslu/inputdevices/ThermistorHelper.java

@@ -3,70 +3,117 @@
 import com.pi4j.context.Context;
 import com.pi4j.io.spi.Spi;
 import com.pi4j.io.spi.SpiConfig;
-import com.pi4j.io.spi.SpiProvider;
+import com.pi4j.io.spi.SpiMode;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import com.pi4j.io.gpio.digital.DigitalInput;
 
 public class ThermistorHelper {
     private static final Logger log = LoggerFactory.getLogger(ThermistorHelper.class);
-    private final DigitalInput sensorInput;
-    private Spi spiDevice;
+    private final Spi spi; // SPI interface for ADC communication
 
-    public ThermistorHelper(Context pi4j, DigitalInput sensorInput) {
-        this.sensorInput = sensorInput;
-        initializeSpi(pi4j);
-    }
+    // Constants for Steinhart-Hart equation (example values; replace with actual thermistor constants)
+    private static final double A = 0.001129148;
+    private static final double B = 0.000234125;
+    private static final double C = 0.0000000876741;
 
-    private void initializeSpi(Context pi4j) {
-        // Obtain SPI provider from Pi4J context
-        SpiProvider spiProvider = pi4j.provider("pigpio-spi");
-        SpiConfig spiConfig = Spi.newConfigBuilder(pi4j)
-                .id("spi-adc0834")
-                .name("ADC0834 SPI Device")
-                .address(0)  // SPI Channel 0
-                .baud(100_000) // Set appropriate baud rate
-                .build();
-
-        // Initialize SPI device
-        this.spiDevice = spiProvider.create(spiConfig);
+    public ThermistorHelper(Context pi4j) {
+        this.spi = initializeADC(pi4j);
     }
 
-    public double getTemperatureCelsius() {
-        int rawValue = getThermistorValue();
-        return convertRawToCelsius(rawValue);
-    }
+    /**
+     * Initialize SPI and ADC settings specific to ADC0834.
+     */
+    private Spi initializeADC(Context pi4j) {
+        try {
+            // Create SPI configuration for the ADC0834
+            SpiConfig spiConfig = Spi.newConfigBuilder(pi4j)
+                    .id("ADC0834")
+                    .name("Thermistor ADC")
+                    .address(17) // SPI channel 0
+                    .baud(1000000) // 1 MHz SPI clock speed
+                    .mode(SpiMode.MODE_0)
+                    .build();
 
-    public double getTemperatureFahrenheit() {
-        double celsius = getTemperatureCelsius();
-        return celsius * 9.0 / 5.0 + 32;
-    }
+            Spi spi = pi4j.create(spiConfig);
+            log.info("SPI and ADC for thermistor initialized.");
+            return spi;
 
-    private double convertRawToCelsius(int rawValue) {
-        double resistance = calculateResistance(rawValue);
-        return 1.0 / (0.001129148 + (0.000234125 * Math.log(resistance)) + (0.0000000876741 * Math.pow(Math.log(resistance), 3))) - 273.15;
+        } catch (Exception e) {
+            log.error("Failed to initialize SPI for ADC0834", e);
+            throw new RuntimeException("SPI initialization failed", e);
+        }
     }
 
-    private double calculateResistance(int rawValue) {
-        double Vout = (rawValue / 255.0) * 3.3; // 8-bit value with 3.3V reference
-        return (10_000 * Vout) / (3.3 - Vout);
+    /**
+     * Reads the raw value from the thermistor via ADC and converts it to resistance.
+     * @return the resistance value of the thermistor
+     */
+    public double getResistance() {
+        double rawValue = readADCValue();
+        return convertRawToResistance(rawValue);
     }
 
-    private int getThermistorValue() {
-        byte[] request = {(byte) 0b11010000, 0};  // Start command for ADC0834
+    /**
+     * Reads the ADC value from the thermistor on ADC0834.
+     * @return the raw ADC value as a double
+     */
+    public double readADCValue() {
+        byte[] packet = new byte[3];
+        byte[] response = new byte[3]; // To store the response from ADC0834
 
-        // Send the request
-        spiDevice.write(request);
+        // ADC0834 requires sending a "start" bit sequence to initiate the read
+        packet[0] = 0x01; // Start bit
+        packet[1] = (byte) (0x80); // Single-ended mode and channel selection (channel 0 for thermistor)
+        packet[2] = 0x00; // Placeholder byte to read data
 
-        // Prepare a buffer for the response
-        byte[] response = new byte[2];
+        try {
+            // Send the command packet and receive response from ADC0834
+            spi.write(packet); // Send the packet
+            spi.read(response); // Read the response into the response array
+
+            // Process the response to extract ADC value (10-bit resolution for ADC0834)
+            int rawValue = ((response[1] & 0x03) << 8) + (response[2] & 0xFF); // Combine bits for 10-bit ADC result
+            log.info("Raw ADC Value: {}", rawValue);
+            return rawValue;
+        } catch (Exception e) {
+            log.error("Failed to read from ADC0834", e);
+            return -1; // Return a flag value indicating an error
+        }
+    }
 
-        // Read the response (if your SPI device allows a separate read)
-        spiDevice.read(response, 0, 2);
 
-        // Extract the ADC value from the response
-        int rawValue = response[1] & 0xFF;
-        log.info("Raw thermistor value from ADC0834: " + rawValue);
-        return rawValue;
+    /**
+     * Converts the raw ADC value to thermistor resistance.
+     * @param rawValue the raw ADC value.
+     * @return the calculated resistance.
+     */
+    private double convertRawToResistance(double rawValue) {
+        // Convert ADC reading to resistance; adjust formula based on thermistor and ADC scaling
+        double voltage = (rawValue / 1023.0) * 3.3; // Assuming a 3.3V reference voltage
+        double resistance = (10000 * (3.3 - voltage)) / voltage; // Example formula for voltage divider circuit
+        log.info("Calculated Resistance: {} ohms", resistance);
+        return resistance;
+    }
+
+    /**
+     * Calculates the temperature in Celsius using the Steinhart-Hart equation.
+     * @return temperature in Celsius.
+     */
+    public double getTemperatureInCelsius() {
+        double resistance = getResistance();
+        double temperatureInKelvin = 1.0 / (A + B * Math.log(resistance) + C * Math.pow(Math.log(resistance), 3));
+        double temperatureCelsius = temperatureInKelvin - 273.15;
+        log.info("Temperature in Celsius: {}", temperatureCelsius);
+        return temperatureCelsius;
+    }
+
+    /**
+     * Converts temperature in Celsius to Fahrenheit.
+     * @return temperature in Fahrenheit.
+     */
+    public double getTemperatureInFahrenheit() {
+        double temperatureFahrenheit = getTemperatureInCelsius() * 9 / 5 + 32;
+        log.info("Temperature in Fahrenheit: {}", temperatureFahrenheit);
+        return temperatureFahrenheit;
     }
 }