Diff: UVSensor.h

Revision:

1:ab9f0e572c98

diff -r 6d4b6c56a7ad -r ab9f0e572c98 UVSensor.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/UVSensor.h	Thu Aug 27 12:42:55 2020 +0000
@@ -0,0 +1,51 @@
+#ifndef __UVSENSOR_H
+#define __UVSENSOR_H
+#include <mbed.h>
+#include <BLE.h>
+AnalogIn UVSignalIn(P0_28);
+
+class UVService {
+public:
+    const static uint16_t UV_SERVICE_UUID = 0xA012;
+    const static uint16_t UV_CHARACTERISTIC_UUID = 0xA013;
+    
+    UVService(BLE &_ble, int16_t initialUVValue) :
+        ble(_ble), UVValue(UV_CHARACTERISTIC_UUID, &initialUVValue)
+    {
+        GattCharacteristic *charTable[] = {&UVValue};
+        GattService uvservice(UV_SERVICE_UUID, charTable, sizeof(charTable) / sizeof(GattCharacteristic *));
+        ble.addService(uvservice);      
+    }
+
+    GattAttribute::Handle_t getValueHandle() const {
+        return UVValue.getValueHandle();
+    }
+    void updateUVValue(uint16_t newValue) {
+        ble.gattServer().write(UVValue.getValueHandle(), (uint8_t *)&newValue, sizeof(uint16_t));
+    }
+
+    void poll()
+    {       
+        uint16_t ADCIn = UVSignalIn.read_u16();
+        // Need to scale this to mW/cm^2
+        // To convert to a voltage : * 3.6/4095
+        // To convert voltage to mW/cm^2 see page 8 of datasheet for ML8511 sensor
+        // This graph is for 3.0V, but the supply in this example is 3.3V. 
+        // I'm ASSUMING that the device output is not a function of voltage supply (within reason)
+        // From Graph : UV power / area is roughly given by:
+        // Power = (Voltage - 1) * 7; 
+        // Need to avoid unsigned overflow
+        // An input of 1V should give an ADC Value of (1/3.6)*4095 = 1137.5 (1138)
+        if (ADCIn >= 1137 )
+            ADCIn = ADCIn - 1137;
+        else
+            ADCIn = 0;
+        ADCIn = ADCIn  / 163; // 4095 / (7*3.6) = 163                   
+        updateUVValue(ADCIn);                
+    }
+private:
+    BLE &ble;
+    ReadOnlyGattCharacteristic<int16_t>  UVValue;
+
+};
+#endif
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