Revision 0:fe642275688d, committed 2016-03-07

Comitter:

joeata2wh

Date:

Mon Mar 07 23:27:37 2016 +0000

Child:

1:0b105d5d31a3

Child:

3:b4592b0ae1e3

Commit message:

test

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ohms.cpp	Mon Mar 07 23:27:37 2016 +0000
@@ -0,0 +1,40 @@
+#include "mbed.h"
+//#include "ohms.h"
+ 
+
+float volDivideCalcRatio(long r1, long r2) {
+  return ((float) r2 / (float) (r1 + r2));
+}
+float voltDivideAdjVolt(float vin, long r1, long r2) {
+  float ratio = ((float) r2 / (float) (r1 + r2));
+  return vin / ratio;
+}
+
+
+
+
+long calcResistV(long refResistR1, float maxV, float measuredV) {
+  float VDrop = maxV - measuredV;
+  float dropRatio =  measuredV / VDrop;  
+  return  (long) (refResistR1 * dropRatio);
+}
+
+
+/*
+
+adjVoltDivide::adjVoltDivide(long r1, long r2, float refVolt) {
+    _r1 = r1;
+    _r2 = r2;
+    _refVolt = refVolt;
+    _ratio = volDivideRatio(r1, r2);
+}
+    
+float adjVoltDivide::read(AnalogIn apin) {
+    return apin.read() / _ratio;    
+}
+
+uint16_t adjVoltDivide::read_u16(AnalogIn apin) {
+    return (int) ((float) apin.read_u16() / _ratio);
+}
+
+*/
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ohms.h	Mon Mar 07 23:27:37 2016 +0000
@@ -0,0 +1,64 @@
+/* Ohms law used to calculate things like resistance from voltage drop
+and to compute read voltage adjusted for dividor. */
+
+#ifndef ohms_H
+#define ohms_H
+#include "mbed.h"
+
+float volDivideCalcRatio(long r1, long r2);
+float voltDivideAdjVolt(float vin, long r1, long r2);
+long calcResistV(long refResistR1, float maxV, float measuredV);
+
+/* Uses a voltage dividor to compute resistance of 
+of R2 based on a known R1 and a source (refVolt) based
+on drop of voltage measured where R1 and R2 connect. 
+normaly used to measure resistance in variable resistance
+circuits such as thermister. 
+
+class VoltDivideAdjVolt {
+
+  public:
+    resistVoltDivide(PinName pin, long r1, float refVolt) {
+        _r1 = r1;
+        _refVolt = refVolt;
+        _pinName = pinName;
+    }
+    ~resistVoltDivide();
+    float read();
+    
+    
+  private:
+    PinName _pin;
+    long _r1;
+    long _r2;
+    float _refVolt;    
+};
+*/
+
+/* adjVoltDivide Compute the actual voltage output after effect 
+of voltage dividor has been removed.  Normally used to compute
+things like true battery voltage when voltage has been level
+shifted into a range safe for use with micro-controller  Assumes
+R1 is connected to source voltage = refVolt and R2 is connected
+to ground measurement is where R2 and R1 meet. Result of read()
+will be voltage as if it had been measured without influence of
+divider. 
+class adjVoltDivide {
+
+  public:
+    adjVoltDivide(long r1, long r2, float refVolt);
+    ~adjVoltDivide();
+    float adjust(float vin);
+    float adjust(int adcin);
+    float read(AnalogIn apin);
+    uint16_t read_u16(AnalogIn apin);
+    float ratio();
+    
+  private:
+    long _r1;
+    long _r2;
+    float _refVolt;
+    float _ratio;
+};
+*/
+#endif
\ No newline at end of file