Is it possible to run more than one pin to an interrupt for sleep/wake purposes?

[karl261]

@AWI I think this Library sounds very promising. What do you think? At least it talks about high and low.

http://playground.arduino.cc/Main/I2CPortExpanderAndKeypads

[AWI]

@karl261 At least it is a more comprehensible library but it does not deal with interrupts (yet).
Are you able to do the following experiment?

• Using the library you quoted, execute the following sketch

#include <Wire.h>
#include <i2ckeypad.h>

#define ROWS 4
#define COLS 3

// With A0, A1 and A2 of PCF8574 to ground I2C address is 0x20
#define PCF8574_ADDR 0x20


i2ckeypad kpd = i2ckeypad(PCF8574_ADDR, ROWS, COLS);

void setup()
{
  Serial.begin(9600);

  Wire.begin();

  kpd.init();
   

  Serial.print("Testing keypad/PCF8574 I2C port expander arduino lib\n\n");

  pcf8574_write(pcf8574_i2c_addr, 0xf0);

}

void loop()
{
}

• measure the input/output pins of the pcf8574 (should be 4 pins low/ 4 pins high)
• measure the power consumption of the pcf8574 (hope it is next to nothing)

IF the above is true we can easily rework te sketch to use the interrupt.

[karl261]

@AWI Thanks. I am in the train now and I am spending my time to try to understand how things work. I also made some progress in my brain. My idea is similar, but you already have a sketch ready. :-) I will try it out, I guess on Saturday. Until then I will try to deepen my knowledge of the libraries.

It is also possible with the "original" library, but you are right: the "new" library is much clearer.

[karl261]

@AWI I found this library:

https://github.com/skywodd/pcf8574_arduino_library

There is a lot of talk about interrupt functionality and it seems to be somehow implemented. But I don't fully understand how it works. Maybe you can make something out of it?

Oh, and maybe in even more detail with some examples, I have not read it yet:

https://github.com/RalphBacon/PCF8574-Pin-Extender-I2C

...but it looks like a software interrupt rather than a hardware interrupt??? I am confused.

... at least for the last example: It does not need any library. It's all quite clear in one sketch.

[AWI]

@karl261 the last sketch does not work with interrupts. It just mentions them.

I would stick with the previous suggestion. Measure the current when you set some outputs to low (low is active 1)

[karl261]

@AWI Yes, I will work with the test sketch on the weekend. It is clear to me now how to set pins of the PCF8574 to HIGH or LOW, and from there we can see.

[karl261]

@AWI Finally:

Yes, it works as expected. 4 pins are 0 V and 4 pins are 3.3 V. The chip is using 2.5 uA.

I had to change a little bit the library, it did not compile and was slightly outdated, also the function we wanted to use was private, but I just did the changes in the library.

I also needed to update to the latest arduino from 1.6.5 to 1.6.12, because i got an error: collect2.exe: error: ld returned 5 exit status. Now it works.

Where do we go from here?

[AWI]

@karl261 Thats good news! What you now have is 4 rows high/ 4 colums low (or v.v.). Now short a column with a row and and expect :baby: an interrupt (= keypress). If that is the case, you can create (or copy) a routine to read the key or keys pushed.

[karl261]

@AWI yeah, I kind of thought the same. I'll try to have rows high and colls low and see if the interrupt pin finally triggers. I should have some pull up on the interrupt pin. Then I'll need to see if I need any pull up or down on the other lines..,

Hope I'll get something done this weekend.

[karl261]

@AWI Ok, so far so good. If I connect 4 high wires to rows and 4 low wires to columns (or vice versa, no idea) then the interrupt pin indeed changes to 0. If I connect the interrupt pin of the IC to D3of the Arduino and then both through a pull up of 10 kOhm to Vcc, the interrupt is at 3.3 V. If I press a key it goes down to 0.040 V. That should be enough to read it as low.

That sounds good, doesn't it? The question is, whether the key library still works...

[AWI]

@karl261 Certainly and it can be pretty straight forward from here. Stick to the library you use (this), it contains all you need. You need to let MySensors catch the interrupt (in the sleep function) and have the callback routine (receive) execute char key = kpd.get_key(); as described in the example.

[karl261]

@AWI It does not compile... I get this stupid error again:

collect2.exe: error: ld returned 5 exit status

But I don't know what to do with it.

[karl261]

current code

sketch

#include <Wire.h>
#include <i2ckeypad.h>

#define ROWS 4
#define COLS 4

// With A0, A1 and A2 of PCF8574 to ground I2C address is 0x20
#define PCF8574_ADDR 0x38
#define PCF8574_PIN_CONFIG 0xf0


i2ckeypad kpd = i2ckeypad(PCF8574_ADDR, ROWS, COLS, PCF8574_PIN_CONFIG);

void setup()
{
  Serial.begin(9600);

  Wire.begin();

  kpd.init();
   

  Serial.print("Testing keypad/PCF8574 I2C port expander arduino lib\n\n");

//  pcf8574_write(pcf8574_i2c_addr, 0xf0);

}

void loop()
{
  char key = kpd.get_key();

  if(key != '\0') {
        Serial.print(key);
  }
}

.cpp

/*
 *  i2ckeypad.cpp v0.1 - keypad/I2C expander interface for Arduino
 *
 *  Copyright (c) 2009 Angel Sancho <angelitodeb@gmail.com>
 *  All rights reserved.
 *
 *  Original source from keypad v0.3 of Mark Stanley <mstanley@technologist.com>
 *  (http://www.arduino.cc/playground/Main/KeypadTutorial)
 *
 *
 *  LICENSE
 *  -------
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 *  EXPLANATION
 *  -----------
 *  This library is designed for use with PCF8574, but can possibly be
 *  adapted to other I2C port expanders
 *
 *  Wiring diagrams for PCF8574 and 4x3 keypad can be found under
 *  examples directory. Library runs correctly without cols pull-up
 *  resistors but it's better to use it
 *
 *  You can change pin connections between PCF8574 and keypad under
 *  PIN MAPPING section below
 *
 *  IMPORTANT! You have to call Wire.begin() before init() in your code
 *
 *  ... and sorry for my poor english!
 */

#include "i2ckeypad.h"
#include <Wire.h>

//extern "C" {
//  #include "WConstants.h"
//}


/*
 *  PIN MAPPING
 *
 *  Here you can change your wire mapping between your keypad and PCF8574
 *  Default mapping is for sparkfun 4x3 keypad
 */

#define COL0  2  // P2 of PCF8574, col0 is usually pin 3 of 4x3 keypads
#define COL1  0  // P0 of PCF8574, col1 is usually pin 1 of 4x3 keypads
#define COL2  4  // P4 of PCF8574, col2 is usually pin 5 of 4x3 keypads
#define COL3  7  // sorry, don't have a 4x4 keypad to try it
#define ROW0  1  // P1 of PCF8574, row0 is usually pin 2 of 4x3 keypads
#define ROW1  6  // P6 of PCF8574, row1 is usually pin 7 of 4x3 keypads
#define ROW2  5  // P5 of PCF8574, row2 is usually pin 6 of 4x3 keypads
#define ROW3  3  // P3 of PCF8574, row3 is usually pin 4 of 4x3 keypads


/*
 *  KEYPAD KEY MAPPING
 *
 *  Default key mapping for 4x4 keypads, you can change it here if you have or
 *  like different keys
 */

const char keymap[4][5] =
{
  "123A",
  "456B",
  "789C",
  "*0#D"
};


/*
 *  VAR AND CONSTANTS DEFINITION. Don't change nothing here
 *
 */

// Default row and col pin counts
int num_rows = 4;
int num_cols = 3;

// PCF8574 i2c address
int pcf8574_i2c_addr;

// PCF8574 i2c pin configuration (high low)
int pcf8574_i2c_pin_cfg;

// Current search row
static int row_select;

// Current data set in PCF8574
static int current_data;

// Hex byte statement for each port of PCF8574
const int hex_data[8] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};

// Hex data for each row of keypad in PCF8574
const int pcf8574_row_data[4] = 
{
  hex_data[ROW1] | hex_data[ROW2] | hex_data[ROW3] |
  hex_data[COL0] | hex_data[COL1] | hex_data[COL2] | hex_data[COL3],
  hex_data[ROW0] | hex_data[ROW2] | hex_data[ROW3] |
  hex_data[COL0] | hex_data[COL1] | hex_data[COL2] | hex_data[COL3],
  hex_data[ROW0] | hex_data[ROW1] | hex_data[ROW3] |
  hex_data[COL0] | hex_data[COL1] | hex_data[COL2] | hex_data[COL3],
  hex_data[ROW0] | hex_data[ROW1] | hex_data[ROW2] |
  hex_data[COL0] | hex_data[COL1] | hex_data[COL2] | hex_data[COL3],
};

// Hex data for each col of keypad in PCF8574
int col[4] = {hex_data[COL0], hex_data[COL1], hex_data[COL2], hex_data[COL3]};


/*
 *  CONSTRUCTORS
 */

i2ckeypad::i2ckeypad(int addr)
{
  pcf8574_i2c_addr = addr;
}

i2ckeypad::i2ckeypad(int addr, int r, int c, int pinc)
{
  pcf8574_i2c_addr = addr;
  num_rows = r;
  num_cols = c;
  pcf8574_i2c_pin_cfg = pinc;
}


/*
 *  PUBLIC METHODS
 */

void i2ckeypad::init()
{
  // All PCF8574 ports high
  pcf8574_write(pcf8574_i2c_addr, pcf8574_i2c_pin_cfg);

  // Start with the first row
  row_select = 0;
}

char i2ckeypad::get_key()
{
  static int temp_key;

  int tmp_data;
  int r;

  int key = '\0';

  // Search row low
  pcf8574_write(pcf8574_i2c_addr, pcf8574_row_data[row_select]);

  for(r=0;r<num_cols;r++) {
    // Read pcf8574 port data
    tmp_data = pcf8574_byte_read(pcf8574_i2c_addr);

    // XOR to compare obtained data and current data and know
    // if some column are low
    tmp_data ^= current_data;

    // Key pressed!
    if(col[r] == tmp_data) {
      temp_key = keymap[row_select][r];
      return '\0';
    }
  }

  // Key was pressed and then released
  if((key == '\0') && (temp_key != '\0'))    
  {
    key = temp_key;
    temp_key = '\0';
    return key;
  }

  // All PCF8574 ports high again
  pcf8574_write(pcf8574_i2c_addr, pcf8574_i2c_pin_cfg);

  // Next row
  row_select++;
  if(row_select == num_rows) {
    row_select = 0;
  }

  return key;
}

/*
 *  PRIVATE METHODS
 */

void i2ckeypad::pcf8574_write(int addr, int data)
{
  current_data = data;

  Wire.beginTransmission(addr);
  Wire.write(data);
  Wire.endTransmission();
}

int i2ckeypad::pcf8574_byte_read(int addr)
{
  Wire.requestFrom(addr, 1);

  return Wire.read();
}

.h

#ifndef i2ckeypad_h
#define i2ckeypad_h

#include <inttypes.h>

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif


class i2ckeypad {
public:
  i2ckeypad(int);
  i2ckeypad(int, int, int, int);
  char get_key();
  void init();
  
private:
  void pcf8574_write(int, int);
  int pcf8574_byte_read(int);
};

#endif

[AWI]

@karl261 I compiled the thing without any errors...
what I did:

• All the files (including the library) in (sub)folder Keypad
• Saved the sketch as Keypad.ino
• Changed <i2ckeypad.h> to "i2ckeypad.h"

p.s. a google search showed that the error occurs with many for no obvious reason...

[karl261]

@AWI yes, I checked Google too, but there is now real solution. I can go back to 1.6.5r5 maybe this works.

[karl261]

@AWI This makes no sense at all! I did what you did, and it compiled. Then I reverted the steps, to my original setup, and it compiles too. WHY? I would be SO HAPPY if somebody could explain.

So the sketch works, but not all keys...

[karl261]

Ok, the keypad works. All keys. Now I have to check the interrupt.

The interrupt is not working any more. At least I don't see it on the Voltmeter. The interrupt pin remains high all the time.

I think this is because to get the key pressed, the library is scanning through the pins and writes different high low states to the ports of the pcf. This kills again the interrupt functionality.

Yes, if I take out the loop function char key = kpd.get_key(); then the interrupt works again, because the library only writes 0xf0 and then it works. When the library is scanning, it does not work anymore.

maybe it is possible to write 0xf0 before going to sleep... Then it won't scan, just wait for the interrupt?

With the knew knowledge of 0xf0 writing I could also test the keypad_I2C library.

[AWI]

@karl261 A lot of thoughts ;-) My idea is:

• write the 0x0f
• go to sleep
• if interrupt (wake-up) scan the keyboard and get the key
• Do whatever you need to do with the key
• write the 0x0f
• go to sleep
• etc...

[karl261]

@AWI I am trapped between "collect2.exe: error: ld returned 5 exit status" errors and non working sketches. This is the world of pain. I am tempted to give up. It just does not make sense. I like things that do make sense...

[AWI]

@karl261 don't give up.. :relaxed: we will get you there. Not much I can do about the 'collect' error but if you post your sketch..