AS3935_ext.cpp

00001 /*
00002 AS3935_ext.cpp - AS3935 Franklin Lightning Sensor™ IC by AMS library
00003 Copyright (c) 2015 T.Naka. All rights reserved.
00004 
00005 This library is free software; you can redistribute it and/or
00006 modify it under the terms of the GNU Lesser General Public
00007 License as published by the Free Software Foundation; either
00008 version 3 of the License, or (at your option) any later version.
00009 
00010 This library is distributed in the hope that it will be useful,
00011 but WITHOUT ANY WARRANTY; without even the implied warranty of
00012 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
00013 Lesser General Public License for more details.
00014 
00015 You should have received a copy of the GNU Lesser General Public
00016 License along with this library; if not, write to the Free Software
00017 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
00018 */
00019 
00020 #include "AS3935_ext.h"
00021 
00022 AS3935_ext::AS3935_ext(PinName sda, PinName scl, int adresse, PinName irqin): AS3935(sda, scl ,adresse)
00023 {
00024     irq = irqin;
00025     wait_ms(11);
00026 }
00027 
00028 void AS3935_ext::reset()
00029 {
00030 
00031     AS3935::reset();
00032     
00033     // Callibrate automatically the internal RCO Oscillators 
00034     registerWrite(0x3D,0xff,0x96);
00035     wait_ms(2);
00036     
00037     // Minimum number of lightning
00038     registerWrite(AS3935_MIN_NUM_LIGH ,1);
00039     
00040 }
00041 
00042 int AS3935_ext::MeasureLCOFreq()
00043 {
00044     DigitalIn display(irq);
00045     int t0;
00046     int t1;
00047     float hz;
00048     unsigned int ticks_per_second;
00049     // int d;
00050 #define LFCLK_FREQUENCY 0x8000
00051 #define RTC_COUNTER_SIZE 0x1000000
00052     ticks_per_second = LFCLK_FREQUENCY / (NRF_RTC1->PRESCALER + 1);
00053 
00054     // Set LCO_FDIV as 32 (0x3) (multiply 128)
00055     wait_ms(20);
00056     registerWrite(AS3935_LCO_FDIV,0x3);
00057 
00058     // Enable display LCO on IRQ
00059     wait_ms(20);
00060     registerWrite(AS3935_DISP_LCO,1);
00061     
00062     wait_ms(100);
00063 
00064     // Wait until IRQ becomes low;
00065     while(display.read() == 1)
00066 
00067     // Wait until IRQ becomes high
00068     wait_ms(20);
00069     while(display.read() == 0);
00070     t0 = NRF_RTC1->COUNTER;
00071 
00072     for(int i=0;i<1000;i++) {
00073         // Wait until IRQ becomes low
00074         while(display.read() == 1);
00075 
00076         // Wait until IRQ becomes high;
00077         while(display.read() == 0);
00078     }
00079     t1 = NRF_RTC1->COUNTER;
00080     // printf("%d\r\n",t1-t0);
00081 
00082     // 1000*128/500k = 0.256sec
00083     hz = 1000* 128 * ticks_per_second / (unsigned int)((t1 - t0 + RTC_COUNTER_SIZE) % RTC_COUNTER_SIZE);
00084 
00085     // Disable display LCO on IRQ pin;
00086     registerWrite(AS3935_DISP_LCO,0);
00087 
00088     return(hz);
00089 }