i2c and 24lc256 reads / writes problem

Zap-o · 2011-06-23 07:27

what am I doing wrong? Trying to simply read and or write to eeprom using the PASM I2C Driver object in the object exchange.

var

 long MemVarOne 

Pub main
 
  i2c.initialize(scl)
  MemVarOne  := Read_HighMem($8000)
 
Pub Read_HighMem(address)

    return i2c.ReadLong(SCL,eepromAddress, address)

Pub Write_HighMem(address, data)

    i2c.WriteLong(SCL,eepromAddress,address, data)

Is it simply because the variable is a long and the object pulls bytes?

Javalin · 2011-06-23 07:41

you need an address for the eeprom - as I2C is a bus each device has an address and locations within a device are address'ed too.

Add something like this:

CON
  eepromAddress = %1010_0000

and try it.

James

Zap-o · 2011-06-23 07:50

Yes sorry my address is

eepromAddress = $A0

Still not going well. I must be overlooking something?

Javalin · 2011-06-23 07:59

can you post your write code? To test the the hardware look at the i2cObject v2.1 in the http://obex.parallax.com which contains a working read/write test.

Zap-o · 2011-06-23 08:08

Sure the problem I have with that code is that I want to read and write a byte not a byte array. Also want to read write a long again not an array.

  
var

 long MemVarOne 
 Byte MemVarTwo
 byte buffer[32]
    
Pub main

  ser.start(31,30,0,19200)
  i2c.initialize(scl)
  MemVarTwo~
  
 
    
  MemVarTwo := 66  
  writeIt   
  readIt  

  ser.str(string("[read ")) 
  ser.dec(buffer[5])
  ser.tx("]")
  
Pri ms(Delay)
         
  Waitcnt((clkfreq / 1_000) * Delay + cnt)
  
PRI readIt

  if i2c.ReadPage(28, EEPROM, eepromAddress, @MemVarTwo, 1)
    abort 

PRI writeIt | startTime

  if i2c.WritePage(28, EEPROM, eepromAddress, @MemVarTwo, 1)
     abort 
  startTime := cnt 
  repeat while i2c.WriteWait(28, EEPROM, eepromAddress)
     if cnt - startTime > clkfreq / 10
       abort

Zap-o · 2011-06-23 08:10

Opps

I solved it.

ser.str(string("[read ")) 
ser.dec(MemVarTwo)
ser.tx("]")

Dave Hein · 2011-06-23 08:32

A 24lc256 is a 256Kbit device, which is 32Kbytes. You can only use addresses from 0 to $7fff. I believe an address of $8000 will wrap around back to 0.

Zap-o · 2011-06-23 09:05

Wow I see $7FFF is true. Thank you sir. Ill set my max address to $7FFF

i2c and 24lc256 reads / writes problem

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