Diff: DAC_MCP4921.hpp

Revision:

0:46d099dfd9d6

Child:

1:e997f4e94491

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DAC_MCP4921.hpp	Sat Mar 14 06:49:49 2015 +0000
@@ -0,0 +1,98 @@
+//------------------------------------------------------
+// Class for single DAC in MCP4921 -- Header
+//      Fast version
+//
+// Default pin assign
+//      D11  SPI Master Out Slave In
+//      D13  SPI Serial Clock
+//      D10  SPI Slave Select ----------------------- TIM4
+//      D12  to MCP4921 LDAC pin
+//      D9   clock for Switched-capacitor filter ---- TIM3
+//
+// Argument cs in constructor must be output of TIM4,
+// i.e. D10(PB_6), PB_7, D15(PB_8), or D14(PB_9)
+//
+// Argument pin in function ScfClockTim3() can be
+// PA_6(D12), PB_4(D5), PC_6, PB_5(D4), PC_7(D9),
+// PC_8, or PC_9
+//
+// 2015/02/02, Copyright (c) 2015 MIKAMI, Naoki
+//------------------------------------------------------
+
+#ifndef DAC_MCP4921_HPP
+#define DAC_MCP4921_HPP
+
+#include "mbed.h"
+#include "tim4_slaveSelect.hpp"
+
+namespace Mikami
+{
+    class DAC_MCP4921
+    {
+    public:
+        // Constructor
+        DAC_MCP4921(
+            PinName mosi = SPI_MOSI,    // D11
+            PinName sclk = SPI_SCK,     // D13
+            PinName cs   = SPI_CS,      // D10
+            PinName ldac = SPI_MISO);   // D12
+
+        // -1.0f <= value <= 1.0f
+        void Write(float value)
+        {
+            if (value < -1.0f) value = -1.0f;
+            if (value >  1.0f) value =  1.0f;
+
+            WriteDac((uint16_t)((value + 1.0f)*2047));
+        }
+
+        // 0 <= value <= 4095
+        void Write(uint16_t value)
+        {   WriteDac((value > 4095) ? 4095 : value); }
+        
+        // generate LDAC negative-going pulse
+        void Ldac()
+        {
+            ld_.write(0);
+            ld_.write(0);   // ensure width of "L" pulse
+            ld_.write(1);
+        }
+
+        // Check busy
+        bool IsBusy()
+        {   return (mySpi_->SR & SPI_SR_BSY) == SPI_SR_BSY; }
+        
+        // Little wait
+        void Wait()
+        {   __NOP(); __NOP(); __NOP(); }
+            
+        // Set clock for switched-capacitor filter
+        void ScfClockTim3(uint32_t clock, PinName pin = D9);
+
+    protected:
+        void SlaveSelect() { ss_->SlaveSelect(); }
+        void WriteSpi(uint16_t value) { mySpi_->DR = value; }
+
+    private:
+        SPI spi_;       // SPI object of mbed
+        Tim4_ss* ss_;
+        DigitalOut ld_; // for LDAC
+
+        // Pointer of I2C
+        SPI_TypeDef* mySpi_;
+
+        // for inhibition of copy constructor
+        DAC_MCP4921(const DAC_MCP4921&);
+        // for inhibition of substitute operator
+        DAC_MCP4921& operator=(const DAC_MCP4921&);     
+        
+        // for internal use
+        virtual void WriteDac(uint16_t value)
+        {
+            while (IsBusy()) {}
+            SlaveSelect();
+            WriteSpi(value | 0x3000);
+        }
+    };
+}
+#endif  // DAC_MCP4921_HPP