bx-adc.cpp

00001 #include "bx-adc.h"
00002 #include "clk_freqs.h"
00003  
00004 #define MAX_FADC            6000000
00005 #define CHANNELS_A_SHIFT    5
00006  
00007 FastAnalogIn::FastAnalogIn(PinName pin, bool enabled)
00008 {
00009     ADCnumber = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
00010     if (ADCnumber == (ADCName)NC) {
00011         error("ADC pin mapping failed");
00012     }
00013  
00014     SIM->SCGC6 |= SIM_SCGC6_ADC0_MASK;
00015  //-----------------------------------------------------
00016     uint32_t port = (uint32_t)pin >> PORT_SHIFT;
00017     SIM->SCGC5 |= 1 << (SIM_SCGC5_PORTA_SHIFT + port);
00018  
00019     uint32_t cfg2_muxsel = ADC_CFG2_MUXSEL_MASK;
00020     if (ADCnumber & (1 << CHANNELS_A_SHIFT)) {
00021         cfg2_muxsel = 0;
00022     }
00023  //------------------------------------------------------    
00024     // bus clk
00025     uint32_t PCLK = bus_frequency();
00026     uint32_t clkdiv;
00027     for (clkdiv = 0; clkdiv < 4; clkdiv++) {
00028         if ((PCLK >> clkdiv) <= MAX_FADC)
00029             break;
00030     }
00031     if (clkdiv == 4)                    //Set max div
00032         clkdiv = 0x7;
00033  
00034     ADC0->SC1[1] = ADC_SC1_ADCH(ADCnumber & ~(1 << CHANNELS_A_SHIFT));
00035  
00036     ADC0->CFG1 = ADC_CFG1_ADIV(clkdiv & 0x3)    // Clock Divide Select: (Input Clock)/8
00037                | ADC_CFG1_MODE(3)               // (16)bits Resolution
00038                | ADC_CFG1_ADICLK(clkdiv >> 2);  // Input Clock: (Bus Clock)/2
00039  
00040     ADC0->CFG2 = cfg2_muxsel            // ADxxb or ADxxa channels
00041                | ADC_CFG2_ADACKEN_MASK  // Asynchronous Clock Output Enable
00042                | ADC_CFG2_ADHSC_MASK;   // High-Speed Configuration
00043  
00044     ADC0->SC2 = ADC_SC2_REFSEL(0);      // Default Voltage Reference
00045  
00046     pinmap_pinout(pin, PinMap_ADC);
00047  
00048     //Enable channel
00049     running = false;
00050     enable(enabled);
00051 }
00052  
00053 void FastAnalogIn::enable(bool enabled)
00054 {
00055     //If currently not running
00056     if (!running) {
00057         if (enabled) {
00058             //Enable the ADC channel
00059             ADC0->SC3 |= ADC_SC3_ADCO_MASK;       // Enable continuous conversion
00060             ADC0->SC1[0] = ADC_SC1_ADCH(ADCnumber & ~(1 << CHANNELS_A_SHIFT));  //Start conversion
00061             running = true;
00062         } else
00063             disable();
00064     }
00065 }
00066  
00067 void FastAnalogIn::disable( void )
00068 {
00069     //If currently running
00070     if (running) {
00071         ADC0->SC3 &= ~ADC_SC3_ADCO_MASK;      // Disable continuous conversion
00072     }
00073     running = false;
00074 }
00075  
00076 uint16_t FastAnalogIn::read_u16()
00077 {
00078     if (!running)
00079     {
00080         // start conversion
00081         ADC0->SC1[0] = ADC_SC1_ADCH(ADCnumber & ~(1 << CHANNELS_A_SHIFT));
00082         // Wait Conversion Complete
00083         while ((ADC0->SC1[0] & ADC_SC1_COCO_MASK) != ADC_SC1_COCO_MASK);
00084     }
00085     if(running && ((ADC0->SC1[0]&ADC_SC1_ADCH_MASK) != (ADC_SC1_ADCH(ADCnumber & ~(1 << CHANNELS_A_SHIFT)))))
00086     {
00087         running = false;
00088         enable();
00089         while ((ADC0->SC1[0] & ADC_SC1_COCO_MASK) != ADC_SC1_COCO_MASK);
00090     }
00091     // Return value
00092     return (uint16_t)ADC0->R[0];
00093 }
00094