I need help with i2c memory

[-c3-]

For my senior project we are using a pic16f84. A large part of the project is storing data in a serial memory chip usint i2c. ive spent 5ish hours trying to figure this out. went through data sheets and searched online, still no success. i am confident my circuit is wired correctly. any help would be greatly appriciated.

the memory used currently is microchip's 24AA512, we also have a 24c01 laying around to play with as well.
i have 2 pull up resistors (5.1k) on scl and sda
write protect is grounded

here is my code,

addr var byte
sda var byte
scl var byte
contR con %10100001
contW con %10100000
x var byte 'test data'
sda=PORTB.0
scl=PORTB.1

addr=%00000000
x=3 'test data is the number 3'
pause 100 'pause just for fun'

I2Cwrite sda,scl,contW,addr,[x] 'should write 3 to address 0, right?'
pause 10
I2Cread sda,scl,contR,addr,[x] 'should read the data'
pause 10
serout Portb.2,4,[x] 'displays data on an LCD'


end

Thanks!

[DynamoBen]

Make your addr a word variable, not byte.

Also make sure you assign a value to your addr before the write command.

Example:

Addr=3
I2Cwrite sda,scl,contW,addr,[x] 'should write 3 to address 0, right?'
pause 10

Finally you may want to add DEFINE I2C_SLOW 1 if things are still not working.

Basically if your wired like the manual says and you do the above it works great.

[NavMicroSystems]

Try this:

addr var word
sda var PORTB.0
scl var PORTB.1
cont con %10100000
x var byte 'test data'
addr=%00000000
x=3 'test data is the number 3'

I2Cwrite sda,scl,cont,addr,[x] 'should write 3 to address 0, right?'
pause 10
I2Cread sda,scl,cont,addr,[x] 'should read the data'
pause 10
serout Portb.2,4,[DEC x] 'displays data on an LCD'


end

[DynamoBen]

Also keep in mind if your hoping to see the number three on the LCD you will need to modify your code a bit.

serout Portb.2,4,[DEC x] 'displays ASCII version of data on an LCD'

[-c3-]

Try this:

addr var word
sda var PORTB.0
scl var PORTB.1
cont con %10100000
x var byte 'test data'
addr=%00000000
x=3 'test data is the number 3'

I2Cwrite sda,scl,cont,addr,[x] 'should write 3 to address 0, right?'
pause 10
I2Cread sda,scl,cont,addr,[x] 'should read the data'
pause 10
serout Portb.2,4,[DEC x] 'displays data on an LCD'


end

when i go to compile i get "bad expression" on serout Portb.2,4,[DEC x]
i am using microcode studio.

[DynamoBen]

You are missing the two pull-up resistors that are required.

Try wiring it identical to the Melabs user manual. This is your best shot at getting it to work. I have included the drawing in this post.

[-c3-]

You are missing the two pull-up resistors that are required.

Try wiring it identical to the Melabs user manual. This is your best shot at getting it to work. I have included the drawing in this post.

you are talking about the 2 pull up resistors on scl and sda correct? they are there. as far as i can tell the only difference between what i have and your picture is the cap from vdd to ground on pin 14. ill put that in and see what happens..

[mister_e]

when i go to compile i get "bad expression" on serout Portb.2,4,[DEC x]
i am using microcode studio.

what about serout Portb.2,4,[#x]???

[-c3-]

what about serout Portb.2,4,[#x]???

that compiles, only problem now is i killed my lcd...... needless to say, from now on i will be a little more careful of which voltage supply i am using.... little puffs of smoke are bad....

[-c3-]

Tried that, still nothing. it makes me wonder if there is something with my circuit i am missing...(i think it is right...)

if any one wants to check the wiring (its not messy)
chip pinouts included

http://www.siue.edu/~bluttin/circuit.htm

thanks

the middle chip is the uln2803, its just driving the leds, ive tried it connected, and unconnected.