Revision 0:4ee0a6513a17, committed 2013-11-14

Comitter:

embeddedartists

Date:

Thu Nov 14 12:19:26 2013 +0000

Child:

1:7eabc2242b8f

Commit message:

First version

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCF8591.cpp	Thu Nov 14 12:19:26 2013 +0000
@@ -0,0 +1,25 @@
+#include "mbed.h"
+#include "PCF8591.h"
+
+PCF8591::PCF8591(PinName sda, PinName scl, int i2cAddr) : m_i2c(sda, scl)
+{
+    m_addr = i2cAddr;
+}
+    
+int PCF8591::read(AnalogIn port)
+{
+    char cmd = port & 0x3; // read from selcted port
+    char val[2] = { 0, 0 };
+    
+    // select the port
+    m_i2c.write(m_addr, &cmd, 1, true);
+    
+    // get the sample
+    if (m_i2c.read(m_addr, val, 2) == 0) {
+        // val[0] is conversion result code from last time (always 0x80)
+        // val[1] is the new value
+        return val[1];
+    }
+    return -1;
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCF8591.h	Thu Nov 14 12:19:26 2013 +0000
@@ -0,0 +1,65 @@
+#ifndef PCF8591_H
+#define PCF8591_H
+
+/**
+ * Interface to the PCF8591 chip (http://www.nxp.com/documents/data_sheet/PCF8591.pdf)
+ * which has four 8-bit analog inputs and one 8-bit analog output.
+ *
+ * @code
+ * #include "mbed.h"
+ * #include "LcdController.h"
+ *
+ * PCF8591 pcf;
+ *
+ * int main(void) {
+ *
+ *    while(1) {
+ *       // read analog value (keep trying until valid)
+ *       int val;
+ *       do {
+ *          val = pcf.read(PCF8591::A0);
+ *          wait(0.01);
+ *       } while(val == -1);
+ *
+ *       // do something with value...
+ *    }
+ * }
+ * @endcode
+ */
+class PCF8591 {
+public:
+
+    enum AnalogIn {
+        A0,
+        A1,
+        A2,
+        A3
+    };
+
+    
+    /** Create an interface to the PCF8591 chip
+     *
+     *
+     *  @param sda the I2C SDA pin
+     *  @param scl the I2C SCL pin
+     *  @param i2cAddr the upper 7 bits of the chip's address
+     */
+    PCF8591(PinName sda = P0_10, PinName scl = P0_11, int i2cAddr = 0x9E);
+    
+    /** Reads one value for the specified analog port
+     *
+     *  @param port the analog in to read (A0..A3)
+     *
+     *  @returns
+     *       the value on success (0..255)
+     *       -1 on failure
+     */
+    int read(AnalogIn port);
+
+private:
+    I2C m_i2c;
+    int m_addr;
+};
+
+#endif
+