Revision 0:9aab4157fdae, committed 2013-11-24

Comitter:

embeddedartists

Date:

Sun Nov 24 12:34:47 2013 +0000

Commit message:

First version

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCA9672.cpp	Sun Nov 24 12:34:47 2013 +0000
@@ -0,0 +1,48 @@
+#include "PCA9672.h"
+ 
+PCA9672::PCA9672(PinName sda, PinName scl) : _i2c(sda, scl)
+{
+    // Software Reset
+    _i2c.start();
+    while(_i2c.write(0x00) !=1);
+    while(_i2c.write(0x06) !=1);
+    _i2c.stop();
+ 
+    /* Software reset is not required. But, gives an 
+       indication if the selected I2C bus frequency works */
+}
+ 
+void PCA9672::frequency(int hz)
+{
+    _i2c.frequency(hz);
+}
+
+void PCA9672::direction(uint8_t inputs)
+{
+    _pins = inputs & 0xff;
+}
+ 
+void PCA9672::write(char value)
+{
+    if (_pins > 0)
+    {
+        _i2c.start();
+        _i2c.write(PCA9672_ADDR);
+        _i2c.write(value | _pins); // all input pins must have a logic 1 as value
+        _i2c.stop();
+    }
+}
+ 
+int PCA9672::read(void)
+{
+    _i2c.start();
+    _i2c.write(PCA9672_ADDR | 1);
+    uint8_t val = _i2c.read(0); // expect NACK
+    _i2c.stop();
+    return val;
+}
+ 
+PCA9672::~PCA9672()
+{
+ 
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCA9672.h	Sun Nov 24 12:34:47 2013 +0000
@@ -0,0 +1,54 @@
+#ifndef PCA9672_H
+#define PCA9672_H
+ 
+#include "mbed.h"
+ 
+//  PCA9672 IIC slave address
+#define  PCA9672_ADDR 0x46
+ 
+ 
+//!Library for the PCA9672 I/O expander.
+/*!
+The PCA9672 is an I2C I/O expander. It has 8 I/O pins.
+*/
+class PCA9672
+{
+public:
+  /*!
+  Connect PCA9672 to I2C port pins sda and scl.
+  */
+  PCA9672(PinName sda, PinName scl);
+  
+  /*!
+  Set the frequency of the I2C interface.
+  */
+  void frequency(int hz);
+ 
+  /*!
+  Setup pin direction (bit = 1 for inputs, 0 for outputs)
+  */
+  void direction(uint8_t inputs);
+  
+  /*!
+  Write the value to the IO Expander (pins XP0-XP7 output)
+  */
+  void write(char value);
+  
+  /*!
+  Read the value of the IO Expander (pins XP0-XP7 input)
+  */
+  int read(void);
+    
+  /*!
+  Destroys instance.
+  */ 
+  ~PCA9672();
+  
+private:
+  
+  I2C _i2c;
+  uint8_t _pins;
+ 
+};
+ 
+#endif
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Nov 24 12:34:47 2013 +0000
@@ -0,0 +1,54 @@
+#include "mbed.h"
+#include "PCA9672.h"
+ 
+PCA9672 ioxp(P0_10, P0_11); //I2C connected to PCA9672 in LPC800-MAX
+ 
+Serial pc(USBTX, USBRX); // tx, rx
+
+static void experiment1_alt1()
+{
+    ioxp.frequency(100000);
+    ioxp.direction(0x80); // mark the push-button pin as input and the rest as outputs
+ 
+    while (1) {
+        uint8_t val = ioxp.read();
+        pc.printf("Reading 0x%02x - bit 7 is %d\n", val, val>>7);
+        if (val & 0x80)
+        {
+            ioxp.write(0x10);
+        }
+        else
+        {
+            ioxp.write(0x20);
+        }
+        wait(.50);
+    }
+}
+
+static void experiment1_alt2()
+{
+    ioxp.frequency(100000);
+    ioxp.direction(0x80 | 0x20); // mark the push-button pins (on breadboard and onboard) as inputs
+ 
+    while (1) {
+        uint8_t val = ioxp.read();
+        pc.printf("Reading 0x%02x - bit 7 is %d, bit 5 is %d\n", val, (val>>7)&1, (val>>5)&1);
+        if (((val & 0xa0)==0xa0) || ((val & 0xa0)==0x00))
+        {
+            // both or neither buttons are pressed
+            ioxp.write(0x10);
+        }
+        else
+        {
+            // exactly one of the buttons are pressed
+            ioxp.write(0x00);
+        }
+        wait(.50);
+    }
+}
+
+int main()
+{
+    //experiment1_alt1(); //onboard button controls yellow (pressed) and green (released) LEDs
+    experiment1_alt2(); //two buttons. Yellow LED lit with exactly one is pressed
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sun Nov 24 12:34:47 2013 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/a9913a65894f
\ No newline at end of file