How to read & write to a 25aa1024 (1 Mbit SPI Bus Serial EEPROM) via 16F88

[mackrackit]

I have tried several different resistor sizes and still nothing.
I think I am actually communicating with it as it "ACK" backs at me...
Here is my current mess...

'  18F6680  24FC1025
    DEFINE OSC 20
    @ __CONFIG    _CONFIG1H, _OSC_HS_1H
    @ __CONFIG    _CONFIG2H, _WDT_OFF_2H & _WDTPS_128_2H
    @ __CONFIG    _CONFIG4L, _LVP_OFF_4L
    
    TRISF = 0
    PORTF = 0
   
    DPIN    VAR PORTF.6    'I2C DATA PIN
    CPIN    VAR PORTF.7    'I2C CLOCK PIN
    CONTR   CON %10100001  'READ CONTROL
    CONTW   CON %10100000  'WRITE CONTROL
    ADDR_HB    VAR BYTE
    ADDR_LB    VAR BYTE
    DATI    VAR BYTE
    DATO    VAR BYTE
    ACK     VAR BIT
    ADDR_HB = %00000000
    ADDR_LB = %00000000
    DATO = %11100000
    CNT VAR BYTE
    CNT = 0
    
    START:CNT = CNT + 1
    GOSUB WRITE_DATA
    PAUSE 100
    GOSUB READ_DATA
    SEROUT2 PORTB.2, 16572,["TEST ",DEC CNT,$d,$a]
    Serout2 PORTB.2, 16572,["DATA IN ",BIN DATI]      
    SEROUT2 PORTB.2, 16572,[$d,$a]
    PAUSE 500
    GOTO START
    
    WRITE_DATA:  ACK=1   :Serout2 PORTB.2, 16572,["ACK ",BIN ACK,$d,$a] 
    GOSUB START_ROM
    SHIFTOUT DPIN,CPIN,1,[CONTW]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    Serout2 PORTB.2, 16572,["ACK ",BIN ACK,$d,$a] 
    SHIFTOUT DPIN,CPIN,1,[ADDR_HB]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    SHIFTOUT DPIN,CPIN,1,[ADDR_LB]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    SHIFTOUT DPIN,CPIN,1,[DATO]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    GOSUB STOP_ROM
    PAUSE 10
    RETURN
    
    READ_DATA:
    GOSUB START_ROM
    SHIFTOUT DPIN,CPIN,1,[CONTR]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    SHIFTOUT DPIN,CPIN,1,[ADDR_HB]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    SHIFTOUT DPIN,CPIN,1,[ADDR_LB]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    GOSUB START_ROM
    SHIFTOUT DPIN,CPIN,1,[CONTR]
    SHIFTIN DPIN,CPIN,0,[ACK\1]
    SHIFTIN DPIN,CPIN,0,[DATI\8]
    GOSUB STOP_ROM
    PAUSE 10
    RETURN
    
    START_ROM:
    HIGH CPIN:HIGH DPIN:LOW DPIN:RETURN
    STOP_ROM:
    HIGH CPIN:LOW DPIN:HIGH DPIN:RETURN

[wolwil]

I changed the Control Byte for the read and the write from this:

contR    CON     %10100001                  
contW    CON     %10100000

to this:

contR    CON     %10100011                  
contW    CON     %10100010

Thinking that because A2 is held high for it to operate then the control bit for A2 should also be a 1... here is the new code:

DEFINE I2C_SLOW 1
SO      con     0                           ' Define serial output pin
T2400   con     0                           ' Define serial mode
contR    CON     %10100011                   ' Define Control byte
contW    CON     %10100010                   ' Define Control byte
addr    CON     %0000000000000111           ' 2 Byte Address of 7
addr2   CON     %0000000000001000           ' 2 Byte Address of 8
D1      CON     %00000111
B0      VAR     BYTE                        ' Var for data being read
B1      VAR     BYTE                        ' Var for data being read

B0 = 0
B1 = 0
I2CWRITE PORTB.1,PORTB.4,contW,addr,[D1]      ' Send the byte 1 to address 7

PAUSE 10                                    ' Wait 10ms for write to complete

I2CREAD PORTB.1,PORTB.4,contR,addr,[B1]      ' Read address 7 into B1
I2CREAD PORTB.1,PORTB.4,contR,addr2,[B0]      ' Read address 8 into B0

Serout SO,T2400,["Addr",#addr,":",#B1," and then Addr",#addr2,":",#B0,13,10] ' Print B1's Value in DEC

this is the output from hyperterm:

Addr7:2 and then 2

Like I said I don't know what it means but it sure is different then what I was getting.

Any thoughts as to why it now is reading a "2" and not 255 or 0??? Its almost like it read the last 2 bits of the write control byte as if the write command wrote the last 2 bits of the control byte to the EEPROM.


UPDATE:
I just switched the control byte to be:

contR    CON     %10100001                  
contW    CON     %10100010

and got this as an output (Note the "6" in Address 8 to begin and then it get over written to "255" the next go around):

Addr7:2 and then Addr8:6
Addr7:2 and then Addr8:255
Addr7:2 and then Addr8:255
Addr7:2 and then Addr8:255
Addr7:2 and then Addr8:255

also I know I'm writing to it because in the example output above I read address 6 with it too (not shown in the code but I added it after posting) and I was reading "255" every time. So this tells me that I am writing a "6" to address 8 but then on the second loop it gets over written/erased to "255" but the "2" in address 7 remains constant and in memory. Now keep in mind that no where in my code do I try to write to address 8 it just happens, more than likely from an over flow from the write to address 7. So basically the byte I am trying to write to 7 gets split into a "2" in address 7 and a "6" in address 8 then address 8 gets overwritten on the 2nd loop to a "255".

and when I do the control byte like this:

contR    CON     %10100011                  
contW    CON     %10100000

I get this (the same as having both A2 bits set to 1):

Addr7:2 and then Addr8:2
Addr7:2 and then Addr8:2
Addr7:2 and then Addr8:2

[ScaleRobotics]

Sorry, read the data sheet wrong. Nevermind

[wolwil]

Whoops it dawned on me what I am doing by changing that Bit. I guess that my novice understanding of this made me stumble upon the fact that I am now writing and reading from a different Chip Select, but seeing how I only have the one chip I dont understand how its reading/writing chip 01 when it should be chip 00.

So I guess where I was calling it the A2 bit its actually the A0 bit that I was changing.

[mackrackit]

How do you have pins A0 and A1 connected?

I have not had a chance to work on this today yet so I do not have any new news.

[wolwil]

How do you have pins A0 and A1 connected?

I have not had a chance to work on this today yet so I do not have any new news.

Tied to ground.

[Dave]

mackrackit, You can't use Shiftout and Shiftin for an I2C bus driven part. That is why you had no luck using it with a 24FC1025... It requires the pullup resistor for communicating the ACK signal back to the processor. Shiftout keeps the pin in an active state wghich ever it is... I recently posted code for talking to 24LC1025's here on the forum... Why not just use it for a starting point... I don't remember which thread it was in reply to but I believe it had to do with I2C....

Dave Purola,
N8NTA

[wolwil]

Dave,

I've searched through all the posts on the 24LC1025 and didn't find any code you posted but I found code that is basically the same as what I have tried already. If you can find the thread you were thinking of that would be great.

The only thing I have not tried is changing is my pullups from 4.7k to 2k and trying to write to it 1 page at a time but if I cant byte-write to begin with I'm sure the page write will not work either. I will try changing the Pullups tonight and see what happens.