mcp23017 (i2c) example code?

mpark · 2008-11-12 09:41

Does anyone have some mcp23017 code I can look at? It's getting late and the datasheet is becoming blurry.
Maybe tomorrow I'll wake up and find that some kind soul has posted some code to get me started.
Being inexperienced in the ways of i2c, I just need to be pointed in the right direction.

nutson · 2008-11-12 15:15

There is MCP23016 code included in one of the OBEX modules, one of the early IIC drivers had a demo program with coding examples for several different devices. Don't remember which one though....

dMajo · 2008-11-12 15:44

nutson said...
There is MCP23016 code included in one of the OBEX modules, one of the early IIC drivers had a demo program with coding examples for several different devices. Don't remember which one though....

I2CObject V2.1

mpark · 2008-11-12 16:01

Thanks, I did look at that, but from the datasheets I got the impression that the 016 and 017 were quite different. The 016 datasheet talks about "command bytes" and the 017 says "register addresses". Are they just different names for the same thing??

dMajo · 2008-11-12 18:19

mpark said...
Thanks, I did look at that, but from the datasheets I got the impression that the 016 and 017 were quite different.············································· YES
The 016 datasheet talks about "command bytes" and the 017 says "register addresses". Are they just different names for the same thing??········ YES

I have given a glance to the datasheets and you are right. The 17 is and "advanced" version ?!? You have the same registers than on 16 (and some others more) but with different addresses so you will need to adapt the 16 driver for 17 operation. The ones with the same name (table 1.5 on both) have the same function.

mpark · 2008-11-12 19:10

Thank you!

Dr_Acula · 2011-11-02 05:28

Sorry to resurrect an old thread, but I am also wondering if there is any code for the MCP23017 (I2C) chip?

A search in the Obex search for MCP23017 comes up blank, as does a number of other searches for chips like this (including the SPI variants).

Spin or Pasm or both would be fine. Searches on Google come up with Duane Johnson's Femtobasic driver but Spin/Pasm would be better!

mpark - did you end up getting some code working?

I'm not looking to use every feature on these chips - in fact all I really want to do is either output some bytes, or input some bytes. I'm intrigued by this chip as it can share the I2C bus which is already used by the eeprom, and hence effectively it can give you more I/O pins on the propeller without actually using any more propeller pins. Cunning!

Any help would be most appreciated.

Ron Czapala · 2011-11-02 06:38

I don't have any Propeller code but I do have some BS2px code which should be pretty simple to convert to SPIN...

JonnyMac · 2011-11-02 10:55

I'm using that chip in a project now; this should help.

Dr_Acula · 2011-11-02 23:53

Thanks guys. Just what I need!

Dr_Acula · 2013-07-26 05:43

A very belated second thankyou to JonnyMac here - I have just got his code working and it is perfect. I initially was using some MCP23106 code and MCP23017 chips and there is a subtle difference between the chips as they have different registers. So if you use MCP23016 code on MCP23017 chips and try to output some bits, the logic Low's are correct, and the logic High's come out as HiZ. Confusing.

Simple answer - use Jonny Mac's code which works perfectly. Is this one maybe for the Obex?

Addit - a little demo using two MCP23017 chips. These are $1.20 each at Futurlec, so for $2.40 you can have another 32 I/O pins for the propeller chip.

PUB MCP23017_Out_Long(n) ' send out a long to two MCP23017 chips
' chips share the I2c bus with the eeprom. Pin 18 reset high, pin 19 and 20 = NC, A0-1-2 on first chip all low
' and on second chip A0 is high. The chips can be run from 3 or 5V (useful for level translation)
' gives a propeller another 32 input and output pins. Futurlec sell these chips for $1.20. DIP28 narrow package.
' if using sockets and can't source 28 pin sockets, use two 14 pin ones. 
' use johnny macs code, the io codes are different for the 23016 and 23017
  mcp23017.start(i2cSCL,i2cSDA,%000)                    ' clock, data, address of chip (2 chips, either 000 or 001)   
  mcp23017.cfg_dira(%00000000)                          ' 0 = output, 1=input
  mcp23017.wr_gpioa(n & %11111111)                      ' output low byte 
  mcp23017.cfg_dirb(%00000000)                          ' 0 = output, 1=input
  mcp23017.wr_gpiob(n >> 8)                             ' second lowest byte
  mcp23017.stop                                         ' stop this chip
  mcp23017.start(i2cSCL,i2cSDA,%001)                    ' clock, data, address of second chip   
  mcp23017.cfg_dira(%00000000)                          ' 0 = output, 1=input
  mcp23017.wr_gpioa(n >> 16)                            ' output second high byte
  mcp23017.cfg_dirb(%00000000)                          ' 0 = output, 1=input
  mcp23017.wr_gpiob(n >> 24)                            ' output high byte
  mcp23017.stop

fixmax · 2013-07-26 07:08

This was a big help to me also. Thanks for the object. One thing I would suggest if this object is posted to the OBEX, is to include additional PUBs for some of the other features of the chip that may be desired in a project. I used interrupt on change and added some of these missing items to his existing object. I have attached the extra code I added below:

the object itself:

pub cfg_iocon(outbits)

'' Write value to IOCON

  i2c.start
  i2c.write(slaveid)
  i2c.write(IOCON)
  i2c.write(outbits)
  i2c.stop

pub cfg_gpinta(outbits)

'' Write value to GPINTENA

  i2c.start
  i2c.write(slaveid)
  i2c.write(GPINTENA)
  i2c.write(outbits)
  i2c.stop

pub cfg_gpintb(outbits)

'' Write value to GPINTENB

  i2c.start
  i2c.write(slaveid)
  i2c.write(GPINTENB)
  i2c.write(outbits)
  i2c.stop

Here is my test code to run it with int on change.

''This code block uses a modified version of Jon "JonnyMac" McPhalen's MCP23017 object
    -added cfg_iocon, cfg_gpinta and cfg_gpintb

OBJ

  mcp1 : "jm_mcp23017_2"
  mcp2 : "jm_mcp23017_2"

CON

  _clkmode        = xtal1 + pll16x           ' Feedback and PLL multiplier
  _xinfreq        = 5_000_000                ' External oscillator = 5 MHz

VAR
  long temp

PUB Main                                      ' Main method
  dira[2]:=0                                  'set address port to input
  dira[3]:=1                                  'set address port to output

' Setup Chip 1
  mcp1.start(0,1,0)                           ' scl=0, sda=1, address=0
  mcp1.cfg_iocon(%0100_0100)                  ' turn on open drain ints, and mirroring
  mcp1.cfg_gpintb(%1111_1111)                 ' turn on int on change for pina 0-7 on portb

  mcp1.cfg_dira(0)                            ' group a configure for outputs
  mcp1.cfg_pola(0)                            ' group a normal polarity
  mcp1.cfg_pua(1)                             ' group a pullup enabled
  mcp1.cfg_dirb(1)                            ' group b configure for inputs
  mcp1.cfg_polb(1)                            ' group b normal polarity 0=normal, 1=inverted
  mcp1.cfg_pub(1)                             ' group b pullup enabled
  
' Setup Chip 2
  mcp2.start(0,1,1)                           ' scl=0, sda=1, address=0
  mcp2.cfg_iocon(%0100_0100)                  ' turn on open drain ints, and mirroring
  mcp2.cfg_gpintb(%1111_1111)                 ' turn on int on change for pina 0-7 on portb

  mcp2.cfg_dira(0)                            ' group a configure for outputs
  mcp2.cfg_pola(0)                            ' group a normal polarity
  mcp2.cfg_pua(1)                             ' group a pullup enabled
  mcp2.cfg_dirb(1)                            ' group b configure for inputs
  mcp2.cfg_polb(1)                            ' group b normal polarity 0=normal, 1=inverted
  mcp2.cfg_pub(1)                             ' group b pullup enabled
   
 repeat                                       ' Endless loop
    temp:=ina[2]
    if temp==0
       mcp1.wr_gpioa(mcp1.rd_gpiob)              ' read input and send to output
       mcp2.wr_gpioa(mcp2.rd_gpiob)              ' read input and send to output
       outa[3]:=1
       waitcnt(clkfreq / 10 + cnt)   
    else
       outa[3]:=0

The test code used a circuit with two MCP23017's on a PPDB. Each MCP23017 had port B set up as in input with port A set up as an output. I used a pushbutton switch on the board for the input, and a LED on the board for the output. I used the interrupt pin bussed off of both MCP23017's to trigger the reads and writes to the chips. This keeps from having to poll continuously and tie up the I2C port with messages. Finally, I just had an LED to turn on with the interrupt so that I could see that. This circuit is not really practical (although it may be), but I wanted to use all the features of the chips. It also may be handy to have each chip capable of 8 inputs and 8 outputs, versus having to have one chip as an input and one as an output.

Again, thanks for the object, this was a great help. Hopefully this code may help someone else use them as well.

Ttailspin · 2013-07-26 09:11

Jon "JonnyMac" McPhalen (aka Jon Williams) and Spin make it easy...:thumb:

{MCP23017 16bit general purpose I/O expander                             
                            &#9484;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9516;&#9516;&#9472;&#9472;&#9472;&#9472;&#9472;&#9488;
                    GPB0&#61626;&#9472;&#61627;[&#9474;1          28&#9474;]&#61626;&#9472;&#61627;GPA7
                    GPB1&#61626;&#9472;&#61627;[&#9474;2          27&#9474;]&#61626;&#9472;&#61627;GPA6
                    GPB2&#61626;&#9472;&#61627;[&#9474;3          26&#9474;]&#61626;&#9472;&#61627;GPA5
                    GPB3&#61626;&#9472;&#61627;[&#9474;4     M    25&#9474;]&#61626;&#9472;&#61627;GPA4
                    GPB4&#61626;&#9472;&#61627;[&#9474;5     C    24&#9474;]&#61626;&#9472;&#61627;GPA3
                    GPB5&#61626;&#9472;&#61627;[&#9474;6     P    23&#9474;]&#61626;&#9472;&#61627;GPA2
                    GPB6&#61626;&#9472;&#61627;[&#9474;7     2    22&#9474;]&#61626;&#9472;&#61627;GPA1
                    GPB7&#61626;&#9472;&#61627;[&#9474;8     3    21&#9474;]&#61626;&#9472;&#61627;GPA0
                     VDD&#9472;&#9472;&#61627;[&#9474;9     0    20&#9474;]&#9472;&#9472;&#61627;INTA
                     VSS&#9472;&#9472;&#61627;[&#9474;10    1    19&#9474;]&#9472;&#9472;&#61627;INTB
                      NC&#9472;&#9472;&#9472;[&#9474;11    7    18&#9474;]&#9472;&#9472;&#61627;RESET (active low)
                     SCL&#9472;&#9472;&#61627;[&#9474;12         17&#9474;]&#61626;&#9472;&#9472;A2 &#61581;
                     SDA&#61626;&#9472;&#61627;[&#9474;13         16&#9474;]&#61626;&#9472;&#9472;A1 &#9472;(I2C address pins)
                      NC&#9472;&#9472;&#9472;[&#9474;14         15&#9474;]&#61626;&#9472;&#9472;A0 &#61572;
                            &#9492;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9496;     


}
CON


        _clkmode = xtal1 + pll16x                     'Standard clock mode * crystal frequency = 80 MHz
        _xinfreq = 5_000_000




  SCL = 0                                             ' Connect to propeller pin 0
  SDA = 1                                             ' Connect to propeller pin 1


'               A2 A1 A0<<<(I2C address pins)must be Biased to VSS="0" or VDD="1"
'                &#9492;&#9488;&#9474;&#9484;&#9496;
  MCP_ID = 00_0011                                ' I2C address for MCP23017 
                  
         
VAR
  
  byte  Abits
  byte  Ainbits
  byte  Bbits
  byte  Binbits
  
OBJ


        GPIO : "jm_mcp23017"
  
PUB Init | counter, count


    GPIO.start(SCL,SDA,MCP_ID)    
    waitcnt(clkfreq / 2 + cnt)


    'All_Output
    HalfIn_HalfOut
    
PUB All_Output
     
    GPIO.cfg_dira(00_0000)        ' Configure all eight pins of PortA to output.
    GPIO.cfg_dirb(00_0000)        ' Configure all eight pins of PortB to output. 
    
    Abits := 01_0101              ' Set PortA bit pattern
    Bbits := 01_0101              ' Set PortB bit pattern
    
  repeat    
    GPIO.wr_gpioa(Abits)             ' Write eight bits to PortA
    GPIO.wr_gpiob(Bbits)             ' Write eight bits to PortB


    waitcnt(clkfreq / 2 + cnt)


    GPIO.wr_gpioa(!Abits)            ' Flip bits with Not(!)
    GPIO.wr_gpiob(!Bbits)
    
    waitcnt(clkfreq / 2 + cnt)


PUB HalfIn_HalfOut


    GPIO.cfg_dira(11_1111)        ' Configure all eight pins of PortA to inputs.
    GPIO.cfg_dirb(00_0000)        ' Configure all eight pins of PortB to output.
     
    GPIO.cfg_pola(11_1111)        ' Invert Polarity of all eight pins of PortA  
                                     ' ( for Pull_up resistors on PPDB push buttons.)
                                     
  repeat
    Ainbits := GPIO.rd_gpioa         ' Read the eight bits from PortA into the Ainbits variable
    GPIO.wr_gpiob(Ainbits)           ' Write the eight bit Ainbits variable to PortB
    
    waitcnt(clkfreq / 16 + cnt)

EDIT: it's amazing what the forum software can do to code...don't cut and paste the above, unless you add the percent signs and missing zeros.. sigh...
I like the MCP23017, seems like it will be handy for reading switches and such.
Purchased from the 'OldBitCollector'( http://www.propellerpowered.us/) himself.

They are large, and do take some real estate investment...

Thanks for sharing your code fixmax,

MCP23017_Demo_MyWay - Archive [Date 2013.07.26 Time 09.34].zip

-Tommy

mcp23017 (i2c) example code?

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