Revision 0:fdfd54fe27dc, committed 2015-06-30

Comitter:

nicolas97

Date:

Tue Jun 30 08:25:56 2015 +0000

Commit message:

Library to interface with AD9837 (function generator)

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/AD9837.cpp	Tue Jun 30 08:25:56 2015 +0000
@@ -0,0 +1,67 @@
+#include "AD9837.h"
+#include "mbed.h"
+
+#define REG_FREQ1   0x8000
+#define REG_FREQ0   0x4000
+#define REG_PHASE0  0xC000
+#define REG_PHASE1  0xE000
+
+#define REG_B28     0x2000
+#define REG_HLB     0x1000
+#define REG_FSEL    0x0800
+#define REG_PSEL    0x0400
+#define REG_PINSW   0x0200
+#define REG_RESET   0x0100
+#define REG_SLEEP1  0x0080
+#define REG_SLEEP12 0x0040
+#define REG_OPBITEN 0x0020
+#define REG_SIGNPIB 0x0010
+#define REG_DIV2    0x0008
+#define REG_MODE    0x0002
+
+#define SIGN_OUTPUT_MASK (REG_OPBITEN | REG_SIGNPIB | REG_DIV2 | REG_MODE)
+
+AD9837::AD9837(PinName mosi, PinName miso, PinName sclk, PinName cs) : _spi(mosi, miso, sclk), _cs(cs) {
+    
+    _spi.format(8, 2);
+    _spi.frequency(1000000);
+}
+
+void AD9837::writeReg(uint16_t value)
+{
+    _cs=0;
+    wait_us(10);
+    _spi.write(value >> 8);
+    _spi.write(value & 0xFF);
+    wait_us(10);
+    _cs=1;
+}
+
+void AD9837::setFrequencyWord(unsigned int reg, uint32_t frequency)
+{
+    writeReg((reg?REG_FREQ1:REG_FREQ0) | (frequency & 0x3FFF));
+    writeReg((reg?REG_FREQ1:REG_FREQ0) | ((frequency >> 14) & 0x3FFF));
+}
+
+void AD9837::setPhaseWord(unsigned int reg, uint32_t phase)
+{
+    writeReg((reg?REG_PHASE1:REG_PHASE0) | (phase & 0x0FFF));
+}
+
+void AD9837::setSignOutput(SignOutput out)
+{
+    m_reg = (m_reg & ~SIGN_OUTPUT_MASK) | out;
+    writeReg(m_reg);
+}
+
+void AD9837::setOutputMode(OutputMode out)
+{
+    if(out == OUTPUT_MODE_TRIANGLE) {
+        m_reg = (m_reg & ~SIGN_OUTPUT_MASK) | out;
+    } if(out == OUTPUT_MODE_SINE) {
+        m_reg &= ~REG_MODE;
+    }else {
+        m_reg = 0x2A;
+    }
+    writeReg(m_reg);
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/AD9837.h	Tue Jun 30 08:25:56 2015 +0000
@@ -0,0 +1,52 @@
+#include "mbed.h"
+
+enum SignOutput {
+    SIGN_OUTPUT_NONE        = 0x0000,
+    SIGN_OUTPUT_MSB         = 0x0028,
+    SIGN_OUTPUT_MSB_2       = 0x0020,
+    SIGN_OUTPUT_COMPARATOR  = 0x0038,
+};
+
+enum OutputMode {
+    OUTPUT_MODE_SINE        = 0x0000,
+    OUTPUT_MODE_TRIANGLE    = 0x0002,
+    OUTPUT_MODE_SQUARE      = 0x0004,
+};
+
+class AD9837
+{
+public:
+    AD9837(PinName mosi, PinName miso, PinName sclk, PinName cs);
+    void setFrequencyWord(unsigned int reg, uint32_t frequency);
+    void setPhaseWord(unsigned int reg, uint32_t phase);
+    void setSignOutput(SignOutput out);
+    void setOutputMode(OutputMode out);
+
+    inline uint32_t computeFrequencyWord(uint32_t frequency) {
+        // This is a manual expansion of (frequency * 2^28) / m_frequency_mhz
+        // Since it doesn't require 64 bit multiplies or divides, it results in
+        // substantially smaller code sizes.
+        uint32_t lval = ((frequency & 0xFF) << 22) / (15625l * m_frequency_mhz);
+        uint32_t mval = ((frequency & 0xFF00) << 14) / (15625l * m_frequency_mhz);
+        uint32_t hval = ((frequency & 0xFF0000) << 6) / (15625l * m_frequency_mhz);
+        return (hval << 16) + (mval << 8) + lval;
+    }
+
+    inline void setFrequency(unsigned char reg, long int frequency) {
+        frequency = this->computeFrequencyWord(frequency);
+        this->setFrequencyWord(reg, frequency);
+    }
+
+    inline void setFrequency(unsigned char reg, float frequency) {
+        this->setFrequencyWord(reg, (frequency * (1l << 28)) / (m_frequency_mhz * 1000000));
+    }
+
+protected:
+    void writeReg(uint16_t value);
+    int m_frequency_mhz;
+    uint16_t m_reg;
+
+private:
+    SPI _spi;
+    DigitalOut _cs;
+};
\ No newline at end of file