+ Reply to Thread
Results 1 to 11 of 11
  1. #1
    Join Date
    Jun 2011
    Location
    Indian Harbour Nova Scotia
    Posts
    105

    Default more i2c and mcp23017

    I have a bunch of LEDs with anodes tied to Vcc through resistors. The cathodes are tied to the outputs of an MCP23107 port expander. I'm using the same setup I had for Arduino that worked, so I know this setup works.

    Trying to get it going in Pic Basic Pro is not working. I have simplified my program to very, very basics to eliminate any "distractions". Here it is:
    Code:
    #config
     __CONFIG _CONFIG1, _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _CPD_OFF & _BOR_ON & _IESO_ON & _FCMEN_ON & _LVP_OFF 
     __CONFIG _CONFIG2, _BOR40V & _WRT_OFF 
    #endconfig
    define LOADER_USED 1
    DEFINE OSC 4                 '4 MHz crystal on LabX1, not the processor speed
    
    
    'TRISC =     %00000000
    SDA         VAR PORTC.4        'i2c data line, 16F887 
    SCL         VAR PORTC.3        'i2c clock line  16F887  
    addr        var byte           'address of port expander
    
     INIT: 
    addr = $42
    I2CWRITE SDA,SCL,addr,[$00,$00] 'set for all output
      
    MAIN:
         I2CWRITE SDA,SCL,addr,[$09, $00]
         pause 100
         I2CWRITE SDA,SCL,addr,[$09, $ff]
         pause 100
    goto main
    Why doesn't this blink the LEDs I have attached to the PE. When I check voltage, it never drops to zero. I've scoped my SDA and SCL lines and they are working fine. I have 5 volts (4.9 actually) on the chip, and the address for this one is $42 (address A1 is high).

    I'm using a LabX1 with 16F887 mcu. I'm expecting all the lights to blink but none do. (I've played with the GPI0 register, making it $12 instead of $09)

    What am I missing? Arduino spoiled me by providing me with libraries that did all the work!

  2. #2

    Default Re: more i2c and mcp23017

    The chip powers up with the IOCON register = 0, so you need to use the "IOCON.BANK=0" column of table 3-1 for the register addresses.

    That puts GPIOA at address $12, not $09.

  3. #3
    Join Date
    May 2013
    Location
    australia
    Posts
    1,388

    Default Re: more i2c and mcp23017

    I'm using the same setup I had for Arduino that worked, so I know this setup works.
    a largely meaningless statement, an Arduino lib could do all sorts of unmentionable things to anything it comes into contact with

    it needs to be
    I'm using this <library> found here <link to lib> with this setup init() function connected this way <schematic or description>

    eg
    Code:
    #include <RFM12B.h>
    // By default the SPI-SS line used is D10 on Atmega328. You can change it by calling .SetCS(pin) where pin can be {8,9,10}
    #define NODEID           1  //network ID used for this uniy
    
    #define NETWORKID       99  //the network ID we are on
    
    //lib  https://github.com/LowPowerLab/RFM12B
     
     radio.Initialize(NODEID, RF12_433MHZ, NETWORKID);
    This is more entertaining than Free to Air TV

  4. #4
    Join Date
    Jun 2011
    Location
    Indian Harbour Nova Scotia
    Posts
    105

    Default Re: more i2c and mcp23017

    I'm using this library: Centipede, found here: http://macetech.com/store/index.php?...products_id=23, with this setup: (this code for 5 different boards). PCB board layout attached.Name:  RGBModelPoint (1).jpg
Views: 71
Size:  135.9 KB I have 5 of these RGB boards using the code below without issue, but I can't get a simpler version (the PBP code) with monochrome LEDs working.

    /*PointsRGBTEST This is working copy.
    RGB test BF29April2018
    Code to check new RGB Points PCB as precursor to the big Star.
    Test of matrix RGB activation. Uses MCP23017 I2C port expanders
    at addresses 20 to 24 and special RGB Star point model. Sequences
    through 7 colors (see below) for 16 lights. Does all one color
    for 16, then next color for same 16. Note RED overwhelms other colors
    so blue or green mixed in show red, instead of magenta and yellow.
    */
    #include <Wire.h>
    #include <Centipede.h>
    Centipede CS;
    const int pins[3] = {//9,10,11 are DIO pins for RGB transistors. Active high turns transistor on.
    9, 10, 11 //use 9, 10, 11 because these are PWM pins on UNO
    };

    int x = 50;//delay between LEDs on/off //
    int i;
    byte b;
    byte p;
    const byte rgb[7] = {0x02, 0x04, 0x08, 0x05, 0x06, 0x0C, 0x0E,}; //00000010= 0x02
    //Red overpowers other lights when lit in combination, eg with green or blue.
    /*const byte Red = ~0x02; //0B00000010 Red on PB1 pin 9 of Uno invert bits 1 here is on, but must be zero for relay
    const byte Green = ~0x04; //0B00000100 Green on PB2 pin 10
    const byte Blue = ~0x08; //0B00001000 Blue on PB3 pin 11
    const byte Magenta = ~0x05; //0B00001010 red and blue
    const byte Yellow = ~0x06; //0B00000110 red and green
    const byte Cyan = ~0x0C; //0B00001100 blue and green
    const byte All = ~0x0E; //0B00001110 all lights should be white
    const byte Seg0 = ~0x01; //0B00000100 Segment 0 on PD0, pin 0 of UNO
    const byte Seg1 = ~0x02; //0B00001000 Segm*/

    void setup() {
    Wire.begin(); // start I2C
    CS.initialize();
    for (byte p = 0; p < 5; p++)//initialize all 5 port expanders
    { CS.portMode(p, 0x00);} //
    // initialize the I/O pins as outputs
    for (int i = 0; i < 3; i++) {
    pinMode(pins[i], OUTPUT);
    }
    }

    void loop()
    {
    for (byte b = 0; b < 7; b++)
    PORTB = rgb[b]; //cycle 7 colors on pins 9,10,11
    for (int p = 0; p < 16; p++)//16 needed to display LED 15
    {CS.portMode(1, 0x00);
    CS.digitalWrite(p, HIGH);//toggle light ON
    delay(x);
    CS.digitalWrite(p, LOW); //turn light OFF
    delay(x);
    }
    }
    Last edited by queenidog; - 24th May 2018 at 14:37.

  5. #5
    Join Date
    Jun 2011
    Location
    Indian Harbour Nova Scotia
    Posts
    105

    Default Re: more i2c and mcp23017

    Yeah, I saw that but $12 didn't work either. Output just won't go low. I measure 3.5 volts or so with my DMM on all GPA pins.

  6. #6
    Join Date
    Jun 2011
    Location
    Indian Harbour Nova Scotia
    Posts
    105

    Default Re: more i2c and mcp23017

    Name:  ScreenHunter 174.jpg
Views: 69
Size:  73.7 KB

    This is what I get on SDA and SCL with that short program.

  7. #7
    Join Date
    Jun 2011
    Location
    Indian Harbour Nova Scotia
    Posts
    105

    Default Re: more i2c and mcp23017

    I put a label at the end of my i2C write statement to flash an LED if there is no acknowledge from the chip.

    there is NO acknowledge...the LED is flashing. So that's a result I will work with. I have extra port expanders (all pretested) and 16F887s.

    Update:
    Changed out port expanders: no change
    Changed out 16F887: no change
    Changed SDA and SCL port from PortC.4 and PortC.3 to PortA.5 and PortA.4: works. Acknowledge led is OFF>

    Any insight into why PortC didn't work but PortA does? ON the LabX1, C.4 and C.3 are designated for I2C.
    Last edited by queenidog; - 24th May 2018 at 17:01.

  8. #8
    Join Date
    May 2013
    Location
    australia
    Posts
    1,388

    Default Re: more i2c and mcp23017

    for what its worth

    this works for me
    Code:
    sda VAR PORTA.1
    scl VAR PORTA.2
    trisa.5=0
    '  pause 2000
    '    Debug "Start",13 ,10
    addr var byte ;mcp control address
    reg var byte  ;mcp register
    da var byte   ;gpioa data
    da=$f8
    addr = $40
    reg=0
    I2CWRITE SDA,SCL,addr,reg,[$00] 'set gpioa all output
    reg=9
    LOOOP:
    I2CWRITE SDA,SCL,addr,reg,[da]
    pause 500
    da=da+1
    GOTO LOOOP
    This is more entertaining than Free to Air TV

  9. #9
    Join Date
    Jun 2011
    Location
    Indian Harbour Nova Scotia
    Posts
    105

    Default Re: more i2c and mcp23017

    Despite the superiority of PBP and Mecanique IDE, working with the i2c commands is a bear! Struggled for a week on it, still no go. Went back to Arduino, and still cursing at all the syntax. However, a quick hookup and I have 80 LEDS spread across 5 boards (PCB above), running all kinds of patterns in COLOR without issue. It's basically the code I submitted (for Arduino) except the CS.digitalWrite is repeated 5 times, once for each board. I've got 20 pages of code done in Arduino, couldn't get one light to light up consistently with PBP.

    Thanks anyway. Going to the Arduino forum now to find out how to create functions (subroutines) to make my code trim and proper.

  10. #10
    Join Date
    May 2013
    Location
    australia
    Posts
    1,388

    Default Re: more i2c and mcp23017

    working with the i2c commands is a bear!
    would you care to provide some code to demonstrate a i2cread/write command that exhibits some problem

    I find it always works as documented .


    I suspect that you have no idea of what the centipede library actually does behind the scenes and that
    you are attempting pbp code based on that total lack of understanding. maybe if you posted some code
    help would be offered all we have seen so far is just totally wrong.

    good luck with your endeavours on the Arduino forum , they just love posts with no code
    This is more entertaining than Free to Air TV

  11. #11
    Join Date
    Oct 2009
    Posts
    567

    Default Re: more i2c and mcp23017

    Quote Originally Posted by richard View Post

    good luck with your endeavours on the Arduino forum , they just love posts with no code
    I also found that they get arsy if you give them too much. I didn't get much joy from the three arduino forums I posted on when porting my thermostat code to the platform. They also don't provide code for you if you're stuck, they expect you to work that part out when they've told you what to do, and if you are new to the platform and still find the syntax strange.

    I found the guys on this forum a lot more friendlier and supportive. It's just a shame that PBP lacks the native support for most modern things - but I2C is one of the basics and I've never had issues when using it to talk to LED driver chips etc.

Similar Threads

  1. need help with PBP, I2C and MCP23017
    By queenidog in forum mel PIC BASIC Pro
    Replies: 5
    Last Post: - 20th May 2018, 00:01
  2. I2C two master on one I2C display
    By Kmt in forum mel PIC BASIC Pro
    Replies: 1
    Last Post: - 22nd September 2014, 20:44
  3. I2C question w/ MCP23017 Port Expanders
    By dsicon in forum mel PIC BASIC Pro
    Replies: 5
    Last Post: - 26th December 2012, 05:47
  4. PIC 18F4550 and MCP23017
    By DaveC3 in forum Code Examples
    Replies: 12
    Last Post: - 4th December 2010, 14:01
  5. I2C, little help please
    By gluphus in forum Serial
    Replies: 2
    Last Post: - 15th March 2006, 04:32

Members who have read this thread : 23

You do not have permission to view the list of names.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts