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Topic: Arduino SPI Pins (Read 3322 times) previous topic - next topic


I Bought 2 of these "Sensors" 

Board Layout / pin out.

Both boards give back different results, so I gave up trying about 4 months back, waste of $70 bucks AUD.

Anyway I though i'd give it one last show.


Arduino Board            MOSI              MISO                   SCK                    SS  (slave)   
Uno or Duemilanove   11 or ICSP-4   12 or ICSP-1   13 or ICSP-3   10   -

So, MOSI 11, MISO 12, SCK 13, Slave Select (10)

Code: [Select]

  LightningDetector.pde - AS3935 Franklin Lightning Sensor™ IC by AMS library demo code
  Copyright (c) 2012 Raivis Rengelis (raivis [at] rrkb.lv). All rights reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 3 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

#include <SPI.h>
#include <AS3935.h>

void printAS3935Registers();

// Function prototype that provides SPI transfer and is passed to
// AS3935 to be used from within library, it is defined later in main sketch.
// That is up to user to deal with specific implementation of SPI
// Note that AS3935 library requires this function to have exactly this signature
// and it can not be member function of any C++ class, which happens
// to be almost any Arduino library
// Please make sure your implementation of choice does not deal with CS pin,
// library takes care about it on it's own
byte SPItransfer(byte sendByte);

// Iterrupt handler for AS3935 irqs
// and flag variable that indicates interrupt has been triggered
// Variables that get changed in interrupt routines need to be declared volatile
// otherwise compiler can optimize them away, assuming they never get changed
void AS3935Irq();
volatile int AS3935IrqTriggered;

// First parameter - SPI transfer function, second - Arduino pin used for CS
// and finally third argument - Arduino pin used for IRQ
// It is good idea to chose pin that has interrupts attached, that way one can use
// attachInterrupt in sketch to detect interrupt
// Library internally polls this pin when doing calibration, so being an interrupt pin
// is not a requirement
AS3935 AS3935(SPItransfer,SS,2);

void setup()
  // first begin, then set parameters
  // NB! chip uses SPI MODE1
  // NB! max SPI clock speed that chip supports is 2MHz,
  // but never use 500kHz, because that will cause interference
  // to lightning detection circuit
  // and chip is MSB first
  // reset all internal register values to defaults
  // and run calibration
  // if lightning detector can not tune tank circuit to required tolerance,
  // calibration function will return false
    Serial.println("Tuning out of range, check your wiring, your sensor and make sure physics laws have not changed!");

  // since this is demo code, we just go on minding our own business and ignore the fact that someone divided by zero

  // first let's turn on disturber indication and print some register values from AS3935
  // tell AS3935 we are indoors, for outdoors use setOutdoors() function
  // turn on indication of distrubers, once you have AS3935 all tuned, you can turn those off with disableDisturbers()
  AS3935IrqTriggered = 0;
  // Using interrupts means you do not have to check for pin being set continiously, chip does that for you and
  // notifies your code
  // demo is written and tested on ChipKit MAX32, irq pin is connected to max32 pin 2, that corresponds to interrupt 1
  // look up what pins can be used as interrupts on your specific board and how pins map to int numbers

  // ChipKit Max32 - irq connected to pin 2
  // uncomment line below and comment out line above for Arduino Mega 2560, irq still connected to pin 2
  // attachInterrupt(0,AS3935Irq,RISING);

void loop()
  // here we go into loop checking if interrupt has been triggered, which kind of defeats
  // the whole purpose of interrupts, but in real life you could put your chip to sleep
  // and lower power consumption or do other nifty things
    // reset the flag
    AS3935IrqTriggered = 0;
    // first step is to find out what caused interrupt
    // as soon as we read interrupt cause register, irq pin goes low
    int irqSource = AS3935.interruptSource();
    // returned value is bitmap field, bit 0 - noise level too high, bit 2 - disturber detected, and finally bit 3 - lightning!
    if (irqSource & 0b0001)
      Serial.println("Noise level too high, try adjusting noise floor");
    if (irqSource & 0b0100)
      Serial.println("Disturber detected");
    if (irqSource & 0b1000)
      // need to find how far that lightning stroke, function returns approximate distance in kilometers,
      // where value 1 represents storm in detector's near victinity, and 63 - very distant, out of range stroke
      // everything in between is just distance in kilometers
      int strokeDistance = AS3935.lightningDistanceKm();
      if (strokeDistance == 1)
        Serial.println("Storm overhead, watch out!");
      if (strokeDistance == 63)
        Serial.println("Out of range lightning detected.");
      if (strokeDistance < 63 && strokeDistance > 1)
        Serial.print("Lightning detected ");
        Serial.println(" kilometers away.");

void printAS3935Registers()
  int noiseFloor = AS3935.getNoiseFloor();
  int spikeRejection = AS3935.getSpikeRejection();
  int watchdogThreshold = AS3935.getWatchdogThreshold();
  Serial.print("Noise floor is: ");
  Serial.print("Spike rejection is: ");
  Serial.print("Watchdog threshold is: ");

// this is implementation of SPI transfer that gets passed to AS3935
// you can (hopefully) wrap any SPI implementation in this
byte SPItransfer(byte sendByte)
  return SPI.transfer(sendByte);

// this is irq handler for AS3935 interrupts, has to return void and take no arguments
// always make code in interrupt handlers fast and short
void AS3935Irq()
  AS3935IrqTriggered = 1;

According to the PDF of of the lightning sensor board, the only thing i have not connected is "SI" pin...

other than that, it's wired up according to http://arduino.cc/en/Reference/SPI for each of the pins.

So where does this "SI" pin go? 


According to the schematic, the SI pin is connected to the SI of the chip.
According to the datasheet of the AS3935, the SI selects the interface. SI = Select Interface (GND -> SPI or VDD -> I²C)

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