Diff: main.cpp

Revision:

0:4a6c8e7e8ea7

Child:

1:25c850668cef

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Mar 20 18:04:55 2015 +0000
@@ -0,0 +1,176 @@
+#include "mbed.h"
+
+DigitalOut LED_3(LED3);
+
+/******
+PIN + SPI CONFIG
+******/
+
+SPI SPI_AFE_ADC_AND_DDS(p5, p6, p7); //SPI0: MOSI, MISO, SCLK
+DigitalOut ADC_nCS(p8);  //ADC_!CS
+DigitalOut DDS_nCS(p15);   //DDS_!CS
+
+SPI SPI_CUR_ADC(p11, p12, p13); //SPI1 - see page 601 of 947
+DigitalOut CUR_nCS(p14);   //DDS_!CS
+
+//  These pins control the Phase register and the Frequency register, IF THE DDS IS CONFIGURED TO BE CONTROLLED BY THE PINS,
+//BY DEFAULT, AND HOW I HAVE IT CONFIGURED IS TO NOT USE THESE PINS, REPEAT, it does NOT USE THE PINS, instead uses the SPI bus.
+//  By toggling them after config, you can create PSK, FSK, BPSK...
+DigitalOut DDS_PSEL(p16);    
+DigitalOut DDS_FSEL(p17);  
+
+DigitalOut SQUARE(p18); //currently does nothing, =1 closes switch to SQUARE path that is not populated
+DigitalOut DDS(p19); //if=1, DDS output connected to TX_PORT
+DigitalOut AFE(p20); //if=1, Electrode routed to Amplification Path
+
+
+#define SSP_SR_TFE (1<<0)
+#define SSP_SR_TNF (1<<1)
+#define SSP_SR_RFE (1<<2)
+#define SSP_SR_RFF (1<<3)
+#define SSP_SR_BSY (1<<4)
+
+void writeReg(uint16_t val){
+    __disable_irq();
+
+    DDS_nCS = 0;
+    //DDS_nCS0;
+    
+    while ( !(LPC_SSP0->SR & SSP_SR_TNF) ); //while ssp is not writable
+    LPC_SSP0->DR = val;                //write this out 
+    while ( (LPC_SSP0->SR & SSP_SR_BSY) ); //wait until transmission is over to pull ncs up
+    
+    DDS_nCS = 1;
+    //DDS_nCS1;
+    
+    __enable_irq();
+}
+
+/******************
+DDS Library ported from https://github.com/arachnidlabs/ad983x/blob/master/ad983x.cpp
+******************/
+#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)
+
+uint16_t m_reg;
+
+enum SignOutput {
+  SIGN_OUTPUT_NONE        = 0x0000,
+  SIGN_OUTPUT_MSB         = 0x0028,
+  SIGN_OUTPUT_MSB_2       = 0x0020,
+  SIGN_OUTPUT_COMPARATOR  = 0x0038,
+};
+
+void setSignOutput(SignOutput out) {
+  m_reg = (m_reg & ~SIGN_OUTPUT_MASK) | out;
+  writeReg(m_reg);
+}
+
+enum OutputMode {
+  OUTPUT_MODE_SINE        = 0x0000,
+  OUTPUT_MODE_TRIANGLE    = 0x0002,
+};
+
+void setOutputMode(OutputMode out) {
+  if(out == OUTPUT_MODE_TRIANGLE) {
+    m_reg = (m_reg & ~SIGN_OUTPUT_MASK) | out;
+  } else {
+    m_reg &= ~REG_MODE;
+  }
+  writeReg(m_reg);
+}
+
+#define REG_FREQ1   0x8000
+#define REG_FREQ0   0x4000
+void setFrequencyWord(bool reg, uint32_t frequency) {
+  writeReg(0x2000);
+  writeReg((reg?REG_FREQ1:REG_FREQ0) | (frequency & 0x3FFF));
+  writeReg((reg?REG_FREQ1:REG_FREQ0) | ((frequency >> 14) & 0x3FFF));
+}
+
+#define REG_PHASE0  0xC000
+#define REG_PHASE1  0xE000
+void setPhaseWord(bool reg, uint32_t phase) {
+  writeReg((reg?REG_PHASE1:REG_PHASE0) | (phase & 0x0FFF));
+}
+
+#define REG_FSEL    0x0800
+void selectFrequency(bool reg) {
+  if(reg) {
+    m_reg |= REG_FSEL;
+  } else {
+    m_reg &= ~REG_FSEL;
+  }
+  writeReg(m_reg);
+}
+
+#define REG_PSEL    0x0400
+void selectPhase(bool reg) {
+  if(reg) {
+    m_reg |= REG_PSEL;
+  } else {
+    m_reg &= ~REG_PSEL;
+  }
+  writeReg(m_reg);
+}
+
+#define REG_RESET   0x0100
+void reset(bool in_reset) {
+  if(in_reset) {
+    m_reg |= REG_RESET;
+  } else {
+    m_reg &= ~REG_RESET;
+  }
+  writeReg(m_reg); //writes 16 bits over SPI
+}
+
+void begin(){
+    reset(true);
+    writeReg(m_reg);
+    // Initialize frequency and phase registers to 0
+    setFrequencyWord(0, 0);
+    setFrequencyWord(1, 0);
+    setPhaseWord(0, 0);
+    setPhaseWord(1, 0);
+    reset(false);
+}
+
+/*******************
+MAIN
+*******************/
+int main() {
+    //init pins
+    DDS_PSEL = 0;
+    DDS_FSEL = 0;
+    SQUARE = 0;
+    DDS = 0;
+    AFE = 0;
+    LED_3 = 1;
+    
+    //nCS lines
+    DDS_nCS = 1;
+    CUR_nCS = 1;
+    ADC_nCS = 1;
+    
+    //init spi
+    SPI_AFE_ADC_AND_DDS.format(16,2);
+    SPI_AFE_ADC_AND_DDS.frequency(33000000);
+    
+    //make sure SPI is setup to mode 2, MSB first
+    //init DDS
+    begin();
+    //output calculation
+    //fOut = fMCLK / 2^28 * FREQREG = 16e6 / 2^28 * FREQREG
+    //FREQREG = fOut * 2^28 / 16e6 = fOut * 16.777216
+    setFrequencyWord(0, 134217728);
+    selectFrequency(0);
+    
+    setSignOutput(SIGN_OUTPUT_MSB);
+    //open the DDS output
+    SQUARE = 1;
+    
+    
+}