PIC 18F4550 and MCP23017

[artha2]

Hey Dave, thanks man
you were right i made that mistake and i looked over and i couldn't catch it, you are having good eyes (i fixed it now).
but still there is no success. even i copy you code and deleted you usb codes line and compile it but i could not get it to work.
I connect all three address pin for my MCP to ground
I pulled up mcp reset pin with a 15K R
I pulled up SDA and SCL pin with two 1k R
portc.3 is my clock and portc.4 is my data
portc.7 is connected to an led just for test, so i know where i am in the program
and this is my codes

again thanks for your time

'* Notes : *
'* : *
'************************************************* ***************
'Includes
include "modedefs.bas"
'************************************************* ***************
'Definitions
DEFINE I2C_SDA PORTc,4
DEFINE I2C_SCL PORTc,3
define ADC_BITS 10
define ADC_CLOCK 3
define ADC_SAMPLEUS 50

'************************************************* ***************
'Variables
A var byte
Chip1 var byte
POT1 var word
POT2 var word

'************************************************* ***************
'Alias
CP VAR PORTc.3
DP VAR PORTc.4

'************************************************* ***************
'Initialization

'Pic 16f877A
adcon1=$02 'left justify A0 and A1
CCP1CON=0 'disable capture/compare
CCP2CON=0
CMCON=7 'disable comparater
option_reg.7=0 'portb pullups enabled

'set ports
trisa=%11111111
trisb=%00000000
trisc=%00000000
trisd=%00000000

'MCP 23017
chip1 = $40
IODIRA con $FF ' port A output
IODIRB con $FF ' port B output
IOCON con $3C ' Defining the MCP Bank as 0 and sequential disable

MCPA con $12
MCPB con $13
MCPAL con $14
MCPBL con $15

'Initialing MCP

i2cwrite dp,cp,$0A,chip1,[iocon]
i2cwrite dp,cp,$0B,chip1,[iocon]
i2cwrite dp,cp,$00,chip1,[iodira]
i2cwrite dp,cp,$01,chip1,[iodirb]



'IODIRA Con $00
'IODIRB con $00
'IPOLA con $00
'IPOLB con $00
'GPINTENA con $00
'GPINTENB con $00
'DEFVALA con $00
'DEFVALB con $00
'INTCONA con $00
'INTCONB con $FF
'IOCON con %00001000
'GPPUA con $00
'GPPUB con $00
'INTFA con $00
'INTFB con $00
'INTCAPA con $00
'INTCAPB con $00
'GPIOA con $00
'GPIOB Con $FF
'OLATA con $00
'OLATB con $FF)

'************************************************* **************
'Main Program

start:
portd =$00
portc.7=0
pause 500
portd = $ff
portc.7=1
pause 500
portc.7=0
pause 500
'I2CWRITE DataPin,ClockPin,Control,{Address,}[Value{,Value...}]{,Label}
I2CWRITE dp,cp,mcpa,chip1,[$FF] 'porta on
portc.7=1
pause 200
I2CWRITE dp,cp,mcpa,chip1,[$00] 'porta off
portc.7=0
pause 200
I2CWRITE dp,cp,mcpal,chip1,[$FF] 'porta on
portc.7=1
pause 200
I2CWRITE dp,cp,mcpal,chip1,[$00] 'porta off
portc.7=0
pause 200
I2CWRITE dp,cp,mcpb,chip1,[$FF] 'portb on
portc.7=1
pause 200
I2CWRITE dp,cp,mcpb,chip1,[$00] 'portb off
portc.7=0
pause 200
I2CWRITE dp,cp,mcpbl,chip1,[$FF] 'portb on
portc.7=1
pause 200
I2CWRITE dp,cp,mcpbl,chip1,[$00] 'portb off
portc.7=0
pause 200

goto start
end

[DaveC3]

The smallest resister I have used for I2C is 4.7K, also you need to initialize the MCP23017 correctly.


Also you have set your port direction to input
IODIRA con $FF ' port A output
IODIRB con $FF ' port B output

to make the port output you need to change the $FF to $00, just like setting a port direction in a PIC.

Good luck

Dave

[artha2]

Ok I changed it to 4.7k R and correct the port direction.
could you please tell me what im doing wrong for initializing the chip? I know the default mode chip's port are all input and all the register's bit are %000000000 according to table 1-6 page 11 pf MCP23017 data sheet it means there is no pull up, inverter. am i right?
i just need to have access to those register address which they are all again at page 11 table 1-6.
and the way to do that with I2CWRITE command is following the help page of PBP which it says: I2CWRITE DataPin,ClockPin,Control,{Address,}[Value{,Value...}]{,Label}
indicate the data pin, indicate clock pin, address of specific register that i want to change (IODIRA &00) table 1-6, address of my chip, [ and value in the bracket ]
is this the correct way?

[cncmachineguy]

Table 1.6 pg 11 shows POR/RST value of IODIRA and IODIRB is %11111111. NOT %00000000. Setting the dir to 1 makes the pin an input.

Maybe you were looking at the next 2 registers? IPOLA and IPOLB?

[DaveC3]

Take a look at your I2C data format

The proper way to send data for this chip is

i2cwrite I2C_SDA, I2C_CLK,control,[Value{..value}]

In your case it should be:

I2C_SDA is PORTC.4 or as you have defined DP
I2C_CLK is PORTC.3 or as you have defined CP

The control needs to be: (assuming you have the address lines connected to zero volts)
%01000000 or $40 for write
%01000001 or $41 for read

{PicBasic actually changes the control bit.0 for you in the statement I2CWRITE and I2CREAD}

So to set a register you need two values, the registers address and the value you want it to be.

To set the IODIRA to be outputs you would send
Value 1 control code for IODIRA is $00 see table 1-3 in the data sheet
value 2 you want to make them outputs so would be $00 (just like setting TRIS in a PIC)

I2CWRITE DP, CP, $40[$00, $00] 'IODIRA is set to output

You also need to set the IOCON register
I2CWRITE DP, CP, $40[$05, %10111000] "see data sheet register 1-6 for details


So to initialize Porta as output you would program this.
I2CWRITE DP, CP, $40[$05, %10111000] "Set configuration
I2CWRITE DP, CP, $40[$00, $00] 'Make porta all outputs

Then to write to the port you would use this:
I2CWRITE DP, CP, $40[$09,$FF] '$09 is the address for GPIOA, $FF would make the porta pins high, to set them low, send values [$09, $00]

You only need to set the weak pull-ups if you are making a port(pin) an input.

Hope this helps
Dave

[artha2]

Thanks Dave,
I really appreciate your time and patient. in I2c command where it asks about the address I thought it asks about chip's physical address, but now thank to you I can fully control this chip and use it. again thanks

Artha

[DaveC3]

You are welcome, glad I could help.

Take care

Dave