File content as of revision 8:f6aa5561f219:

/*
 * mbed Application program for the mbed LPC1114FN28
 * Test program -> Check LED & Switch function 
 *
 * Copyright (c) 2014 Kenji Arai / JH1PJL
 *  http://www.page.sannet.ne.jp/kenjia/index.html
 *  http://mbed.org/users/kenjiArai/
 *      Created: June      13th, 2014
 *      Revised: June      13th, 2014
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#include "mbed.h"

#define DEBUG       1           // 1=Debug, 0=Normal

#define VREF_VOLT   2.482       // TA76431F Vref real measued data
#define R_FIX       9930        // 10K ohm <- real measued data
#define VOL_OFFSET  4           // Offset data ,= real measured data
#define CDS_TBL_SIZE    13

DigitalOut  myled0(dp28);       // LED for Debug
DigitalOut  myled1(dp14);       // Indicate state transition
DigitalOut  analog_pwr(dp6);    // VCC for analog interface (vol, cds and vref)
DigitalOut  vref_pwr(dp4);      // VCC for Vref
DigitalIn   sw_chng(dp1,PullUp);// SW for select
DigitalIn   sw_mode(dp2,PullUp);// SW for Mode change
AnalogIn    cds(dp11);          // Input / CDS data
AnalogIn    vref(dp9);          // Input / Bandgap 2.5V
AnalogIn    vol(dp10);          // Input / contrast volume
Serial pc(dp16,dp15);

typedef enum {CDS = 0, VREF, VOL} ADC_Select;

float av_cds, av_vref, av_vol, cal_vcc;
float r_cds, lux;
uint32_t nor_vol;

// Cds GL5528 (Dark Resistance 1 Mohm type) SENBA OPTICAL & ELECTRONIC CO.,LTD.
//      Table value referrence: http://homepage3.nifty.com/skomo/f35/hp35_20.htm
const float lux_cds[CDS_TBL_SIZE][2] =
    {{50,21194},{100,8356},{200,3294},{400,1299},{800,512},{1600,202},{3200,79.6},{6400,31.4},
    {12800,12.4},{25600,4.88},{51200,1.92},{102400,0.758},{409600,0.118}};

void adc_normalize( ADC_Select n ){
int i;
float x1,y1,dx;

    switch (n){
    case CDS:
        // v_adc = Rfix / (Rcds + Rfix)
        // Rcds = ( Rfix / v_adc ) - Rfix 
        r_cds = (R_FIX / av_cds) - R_FIX;
        // CDS resistance to Lux conversion using convertion table (luc_cds[][])
        //  with Linear interpolation method
        for (i =0; i < CDS_TBL_SIZE; i++){
            if ( r_cds <= lux_cds[i][0]){
                break;
            }
        }
#if DEBUG
        pc.printf("i=%d, ", i);
#endif
        if (i == 0){
            lux = lux_cds[0][1];
        } else if ( i == CDS_TBL_SIZE ){
            if ( r_cds <= lux_cds[i][0]){
                lux = lux_cds[i-1][1];
            }
        } else {
            y1 = lux_cds[i-1][1] - lux_cds[i][1];
            x1 = lux_cds[i][0] - lux_cds[i-1][0];
            dx = r_cds - lux_cds[i-1][0];
            lux = lux_cds[i-1][1] - ((dx/x1) * y1);
#if DEBUG
            pc.printf("y1:%f, x1:%f, dx:%f, lux_tbl:%f\r\n", y1, x1, dx, lux_cds[i-1][1]);
#endif
        }
        break;
    case VREF:
        //  vref = VREF_VOLT / VCC -> VCC = VREF_VOLT / vref
        cal_vcc = VREF_VOLT / vref;
        break;
    case VOL:
        // Vol center = 1.00 (actual 100)
        nor_vol = (uint32_t)(av_vol * 200) + VOL_OFFSET;
        break;
    }
}

void adc_all_read( void){
    av_cds = av_cds *0.5 + cds.read() * 0.5;
    av_vref = av_vref *0.9 + vref.read() * 0.1;
    av_vol = av_vol *0.2 + vol.read() * 0.8;
}

void adc_init( void){
    analog_pwr = 1;
    vref_pwr = 1;
    wait(0.2);  
    av_cds = cds.read();
    av_vref = vref.read();
    av_vol = vol.read();
    wait(0.1);
    adc_all_read();
    wait(0.1);
    adc_all_read();
    analog_pwr = 0;
    vref_pwr = 0;
}

int main() {
    pc.baud(9600);
    pc.printf("mbed LPC1114FN28 test program by JH1PJL created on "__DATE__"\r\n");
    while(1) {
        analog_pwr = 1;
        vref_pwr = 1;
        wait(0.2);
        adc_all_read();
        //analog_pwr = 0;
        adc_normalize( CDS );
        adc_normalize( VREF );
        adc_normalize( VOL );        
        myled0 = 1;
        myled1 = 1;
        if (sw_chng == 1){  // SW Off
            pc.printf("CDS:%.0fohm -> %.1flux, Vcc:%.3fV, Vol:%d\r\n", r_cds, lux, cal_vcc, nor_vol);
        } else {            // SW On
            pc.printf("CDS:%f, Vref:%f, Vol:%f\r\n", av_cds, av_vref, av_vol);
        }
        myled0 = 0;
        myled1 = 0;
        wait(0.8);     
    }
}