Revision 2:26893e7c0068, committed 2018-02-09

Comitter:

natgovor

Date:

Fri Feb 09 16:31:44 2018 +0000

Parent:

1:126dd2f5fc2d

Commit message:

Analog to digital conversion. Reads voltage and displays it in the terminal.

Changed in this revision

--- a/main.cpp	Wed Jan 24 21:55:43 2018 +0000
+++ b/main.cpp	Fri Feb 09 16:31:44 2018 +0000
@@ -7,13 +7,22 @@
 
 Ticker tick;                // Ticker for reading analog
 AnalogIn ain(A0) ;          // Analog input
-DigitalOut led1(LED_RED);   // Red LED
+
+const int states_number = 6; // number of leds + 1
+DigitalOut leds[5] = { PTA13, PTD5, PTD0, PTD2, PTD3 };
+
+// button setup
+DigitalIn button(PTE1, PullUp);
+enum buttonPos { up, down, bounce }; // Button positions
+buttonPos pos = up ;
+int bcounter = 0 ;
 
 Serial pc(USBTX, USBRX); // tx, rx, for debugging
 
 // Message type
 typedef struct {
   uint16_t analog; /* Analog input value */
+  bool buttonPressed;
 } message_t;
 
 // Mail box
@@ -24,7 +33,33 @@
 // Every 10th value is sent to mailbox
 volatile int samples = 0 ;
 volatile uint16_t smoothed = 0 ; 
+volatile bool pressEvent = false;
 void readA0() {
+    // Check button state
+    switch (pos) {
+        case up :
+            if (!button.read()) {    // now down 
+                pressEvent = true;
+                pos = down ;
+            }
+            break ;
+        case down : 
+            if (button == 1) { // no longer down
+                bcounter = 3 ; // wait four cycles
+                pos = bounce ;
+            }
+            break ;
+        case bounce :
+            if (button == 0) { // down again - button has bounced
+                pos = down ;   // no event
+            } else if (bcounter == 0) {
+                pos = up ;     // delay passed - reset to up
+            } else {
+                bcounter-- ;   // continue waiting
+            }
+            break ;
+    }
+    
     smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ;
     samples++ ;
     if (samples == 10) {
@@ -32,9 +67,11 @@
         message_t *mess = mailbox.alloc() ; // may fail but does not block
         if (mess) {
             mess->analog = smoothed ;
+            mess->buttonPressed = pressEvent;
             mailbox.put(mess); // fails but does not block if full
         }
         samples = 0;
+        pressEvent = false;
     }       
 }
 
@@ -48,25 +85,69 @@
     s[0] = '0' + (v % 10) ;
 }
 
+void lightLeds(int threshold_index) {
+    int leds_number = states_number - 1;
+    for (int i=0; i<leds_number; i++) {
+        if (i <= threshold_index - 1) {
+            leds[i] = 1;
+        } else {
+            leds[i] = 0;
+        }
+    }
+}
+
+void calculate_thresholds(int max_voltage, int* threshold) {
+    int interval = max_voltage / states_number;
+    for (int i = 0; i < states_number; i++) {
+        if (i == 0) {
+            threshold[i] = interval;
+        } else {
+            threshold[i] = threshold[i-1] + interval;
+        }
+    }
+}
+
 // Main program
 //   Initialise variables
 //   Attach ISR for ticker
 //   Procss messages from mailbox    
 int main() {
-    led1 = 1 ; // turn off 
     int volts = 0 ;
-    const int threshold = 100 ;
     int counter = 0 ;
     char vstring[] = "X.XX\r\n" ;
+    
+    //int max_voltage = 330;
+    int threshold[states_number];
+    
+    calculate_thresholds(330, threshold);   
 
     tick.attach_us(callback(&readA0), 10000); // ticks every 10ms
     while (true) {
         osEvent evt = mailbox.get(); // wait for mail 
         if (evt.status == osEventMail) {
             message_t* mess = (message_t*)evt.value.p ;
+            bool pressEvent = mess->buttonPressed;
+            if (pressEvent) {
+                // recalculate treshold
+                calculate_thresholds(volts, threshold);
+            }
             volts = (mess->analog * 330) / 0xffff ;
             mailbox.free(mess) ;  // free the message space
-            if (volts > threshold) led1 = 0 ; else led1 = 1 ;
+             
+            if (volts < threshold[0]) {
+                lightLeds(0);
+            } else if (volts > threshold[0] && volts < threshold[1]) {
+                lightLeds(1);
+            } else if (volts > threshold[1] && volts < threshold[2]) {
+                lightLeds(2);
+            } else if (volts > threshold[2] && volts < threshold[3]) {
+                lightLeds(3);
+            } else if (volts > threshold[3] && volts < threshold[4]) {
+                lightLeds(4);
+            } else if (volts > threshold[4]) {
+                lightLeds(5);
+            }
+            
             vToString(volts, vstring) ;
             counter++ ;
             if (counter == 10) {  // limit bandwidth of serial