Using Multiple EEPROMs

[Tom Gonser]

THANKS MUCH!!

I am glad I was on the right track. Do you know of any higher density memory that can be used like this? I'd really like 2-4m per chip if it existed, was easy to write to using PBP, and was not to horribly expensive..

Tom

[Tom Gonser]

OK - I have the EEPROMS setup per what has been described, and we can compile and it LOOKS like it sends data to the chips, but I cant' see anything coming back.. I read in 1000 values from 0 to 999 in an 'x' loop, then read them back, and all I see are '0's... Help! I think my naming of the chips is wrong..

Chip is an 16F876A.

I have two chips 24LC515 512k .. I have given them names:

DPIN var PortA.2 ' I2C data
CPIN var PortA.1 ' I2C clock
address var byte
value var byte

Chip1 con %10100000 ' address of chip1
Chip2 con %10100100 ' address of chip2

Init:
PORTA = %00000 'Initialize PortA to all zeros - all output
TRISA = %00000 'All port A output
PORTB = %00000101 'Initialize PortB - port 2 for data, port 0 for button interrupt
TRISB = %00000101 'Port 2 inputs are 0 and 2
T1CON = %01000000 'Timer1 1:1 prescale(?). Timer1 off
----------------------------------------------------------------------

I read and write to them like this: For this demo I only will write 1000 records in each chip.


storedata:
for x = 0 to 1000
i2cwrite dpin,cpin,chip1,x,x
pause 10
serout2 Apinout, 16468, [I,CLR]
serout2 Apinout, 16468, [I,L1_C1]
serout2 Apinout, 16468, ["Writing: C1 ",#x]
Next x

for x = 0 to 1000
i2cwrite dpin,cpin,chip2,x,x
pause 10
serout2 Apinout, 16468, [I,CLR]
serout2 Apinout, 16468, [I,L1_C1]
serout2 Apinout, 16468, ["Writing: C2 ",#x]
Next x

...
...
Readitback:
' read memory contents to screen.
serout2 Apinout, 16468, [I,CLR]
serout2 Apinout, 16468,[I,L1_C1]
Serout2 AGPSout, 16572, ["Memory Dump Chip 1: ", 10,13]
Address =0
p=0
x=0
For p = 1 to 29 ' total sentences storable in memory
serout2 AGPSout, 16572, ["SS ",#p,": "]
for address = X to (X+34)
I2Cread Dpin,Cpin,Chip1, address, value
serout2 AGPSout, 16572, [",",#value]
next address
serout2 AGPSout, 16572, [10,13]
X=X+34
next p

serout2 Apinout, 16468, [I,CLR]
serout2 Apinout, 16468,[I,L1_C1]
Serout2 AGPSout, 16572, ["Memory Dump Chip 2: ", 10,13]
Address =0
p=0
x=0
For p = 1 to 29 ' total sentences storable in 1k
serout2 AGPSout, 16572, ["SS ",#p,": "]
for address = X to (X+34)
I2Cread Dpin,Cpin,Chip2, address, value
serout2 AGPSout, 16572, [",",#value]
next address
serout2 AGPSout, 16572, [10,13]
X=X+34
next p

Return

[mister_e]

fast overlook... did you read caefully your EEPROM datasheet??? Try to use a WORD sized variable for your address.. also look how many bits must be shift for address + control word and how.

[Tom Gonser]

Working now... It was simply a mis-wired A2 pin. With everything neatly in place, resistors in line, etc. We have both chips working fine. I was also off in the chip 2 definitin by a bit. Now it works great. Thanks for the help!

Chip1 con %10100000 ' address of chip1
Chip2 con %10100010 ' address of chip2

TG