Diff: PCF8574_EnableBus.cpp

Revision:

2:1dab1089c332

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCF8574_EnableBus.cpp	Sat Aug 20 12:49:44 2011 +0000
@@ -0,0 +1,130 @@
+/* PCF8574_EnableBus - Use the PCF8574 I2C Port Extender for controlling the Chip Enable 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_EnableBus.h"
+
+
+/** Create an PCF8574_EnableBus 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_EnableBus::PCF8574_EnableBus(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();
+}
+
+
+/** Set or Reset Chip Select pins on Enable Bus
+ *
+ * @param CS_Pin cs_pin 
+ * @param Bit_Level cs_level
+*/
+void PCF8574_EnableBus::chipselect (CS_Pin cs_pin, Bit_Level cs_level) {
+    int result = 1;
+      
+    switch (cs_pin) {
+     case CS_SWITCH : if (cs_level == LOW)
+                         _enable_bus = ~D_CS_SWITCH; // CS Pin Low, make sure that only one CS is active
+                      else
+                         _enable_bus |= D_CS_SWITCH; // CS Pin High
+                      break;
+     case LATCHEN_1 : if (cs_level == LOW)
+                         _enable_bus = ~D_LATCHEN_1; // CS Pin Low, make sure that only one CS is active
+                      else
+                         _enable_bus |= D_LATCHEN_1; // CS Pin High
+                      break;
+     case LATCHEN_2 : if (cs_level == LOW)
+                         _enable_bus = ~D_LATCHEN_2; // CS Pin Low, make sure that only one CS is active
+                      else
+                         _enable_bus |= D_LATCHEN_2; // CS Pin High
+                      break;
+     case CS_BRIGHT : if (cs_level == LOW)
+                         _enable_bus = ~D_CS_BRIGHT; // CS Pin Low, make sure that only one CS is active
+                      else
+                         _enable_bus |= D_CS_BRIGHT; // CS Pin High
+                      break;
+     case CS_DISP : if (cs_level == LOW)
+                         _enable_bus = ~D_CS_DISP;   // CS Pin Low, make sure that only one CS is active
+                      else
+                         _enable_bus |= D_CS_DISP;   // CS Pin High
+                      break;
+     
+     default:          // Oops, we should never end up here....
+                      result = -1;
+    }
+
+    _write();                              // Write chip enable bits to bus
+}
+
+/** Set or Clear the Reset pin on Enable Bus
+ *
+ * @param Bit_Level rst_level
+*/
+void PCF8574_EnableBus::reset (Bit_Level rst_level) {
+
+    if (rst_level == LOW) {
+        _reset_pin = 0x00;                 // Reset Pin Low
+      }               
+    else {
+        _reset_pin = D_RESET;              // Reset Pin High
+    }     
+    
+    _write();                              // Write RST bit to bus
+}
+ 
+               
+/** Set or Clear the NoGo pin on Enable Bus
+ *
+ * @param Bit_Level nogo_level
+*/
+void PCF8574_EnableBus::nogo (Bit_Level nogo_level) {
+
+    if (nogo_level == LOW) {
+        _nogo_pin = 0x00;                  // NOGO Pin Low
+      }               
+    else {
+        _nogo_pin = D_NOGO;                // NOGO Pin High
+    }     
+    
+    _write();                              // Write NoGo bit to bus
+}
+ 
+
+/** Optimised EnableBus write operation.
+ * @param byte the value to output on the bus
+*/
+void PCF8574_EnableBus::_write(char byte) {
+    char data[1];
+    
+    data[0] = byte;
+    _i2c.write(_writeOpcode, data, 1);    // Write value to bus   
+}
+
+/** Optimised EnableBus write operation.
+ * @param 
+*/
+void PCF8574_EnableBus::_write() {
+    char data[1];
+    
+    data[0] = (_enable_bus & D_ENABLE_MSK) | _reset_pin | _nogo_pin;      // Combine enable bits and control bits
+    _i2c.write(_writeOpcode, data, 1);    // Write value to bus   
+}
+
+
+/** Init PCF8574_EnableBus
+ * @param
+ * @returns 
+ */
+void PCF8574_EnableBus::_init() {
+    _enable_bus = 0xFF;                    // Make sure that all CS pins are disabled
+    _reset_pin  = D_RESET;                 // Make sure that Reset pin is disabled
+    _nogo_pin   = D_NOGO;                  // Make sure that NoGo pin is disabled    
+    _write();                              // Write value to bus    
+}
\ No newline at end of file