Diff: PCF8574_DataBus.cpp

Revision:

0:12207c70f4ea

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCF8574_DataBus.cpp	Sun Jan 25 17:50:03 2015 +0000
@@ -0,0 +1,75 @@
+/* PCF8574_DataBus - Use the PCF8574 I2C Port Extender for controlling the Data Bus
+ * Copyright (c) 2011 Wim Huiskamp
+ *
+ * Released under the MIT License: http://mbed.org/license/mit
+ *
+ * version 0.2 Initial Release
+*/
+#include "mbed.h"
+#include "PCF8574_DataBus.h"
+
+/** Create an PCF8574_DataBus object connected to the specified I2C object and using the specified deviceAddress
+ *
+ * @param I2C &i2c the I2C port to connect to 
+ * @param char deviceAddress the address of the PCF8574
+*/
+PCF8574_DataBus::PCF8574_DataBus(I2C &i2c, char deviceAddress) : _i2c(i2c) {
+   _writeOpcode = deviceAddress & 0xFE; // low order bit = 0 for write
+   _readOpcode  = deviceAddress | 0x01; // low order bit = 1 for read
+   _init();
+}
+
+/** Optimised DataBus write operation.
+ * @param byte the datavalue to output on the bus
+*/
+void PCF8574_DataBus::write(char byte) {
+    char data[1];
+    
+    data[0] = byte;
+    _i2c.write(_writeOpcode, data, 1);    // Write datavalue to bus   
+}
+
+/** Optimised DataBus read operation.
+ *
+ * @returns current data from Databus 
+*/
+char PCF8574_DataBus::read() {
+    char data[1];
+
+//Make sure that databus is enabled for Read
+//    data[0] = 0xFF;                       // Init Port for datainput by Writing 0xFF 
+//   _i2c.write(_writeOpcode, data, 1);    // Write to bus   
+    
+    _i2c.read(_readOpcode, data, 1);      // Read data from bus
+     
+   return data[0];
+}
+
+
+/** Enable databus for Write or Read
+ *
+ * @param Bus_Dir bus_dir
+*/
+void PCF8574_DataBus::busdir (Bus_Dir bus_dir) {
+
+    if (bus_dir == READ) {
+      // Make sure that databus is enabled for READ
+      write(0xFF);                          // Init Port as input by Writing 0xFF 
+            
+    }                
+    else {
+      // Make sure that databus is enabled for WRITE   
+      write(0xFF);                          // Not really needed, just Init Port to safe settings
+    }      
+}
+
+
+
+/** Init PCF8574_DataBus
+ * @param
+ * @returns 
+ */
+void PCF8574_DataBus::_init() {
+ 
+    busdir(WRITE);                          // Init Port as output 
+}
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