I2C and Si570 Synthesiser

g3cwi

Hi there

I am starting to get to grips with I2C to program an Si570 synthesiser. I can see the Si570 device on the I2C bus and get an ack from it. However, I am having trouble reading from it. I am using Javalin's Object. I suspect I am feeding the register addresses wrongly. Any ideas? BTW I am new to this so use simple words! Thanks.

Debug o/p:
I2C Demo (v2)!
Scanning I2C Bus....
Scan Addr : %10100000, ACK
Scan Addr : %10101010, ACK
i2cScan found 2 devices!
EEPROM Present
Si570 Present
Si570 DEMO
Read Si570 Location=00007, data byte=00002
Read Si570 Location=00008, data byte=00002
Read Si570 Location=00009, data byte=00002
Read Si570 Location=00010, data byte=00002
Read Si570 Location=00011, data byte=00002
Read Si570 Location=00012, data byte=00002
Read Si570 Location=00013, data byte=00002
Read Si570 Location=00014, data byte=00002
Read Si570 Location=00015, data byte=00002
Read Si570 Location=00016, data byte=00002
Read Si570 Location=00017, data byte=00002
Read Si570 Location=00018, data byte=00002
Si570 demo done.

CON
  _clkmode      = xtal1 + pll16x
  _xinfreq      = 5_000_000
  _stack        = 50
    
  i2cSCL        = 28
  i2cSDA        = 29 

 
  EEPROMAddr    = %1010_0000
  Si570Addr     = %1010_1010   'AA
 

  ' EEPROM data base address - i.e 32K (assumes a 64kb eeprom installed!!)
  EEPROM_Base     = $8000
  
  ' debug - USE onboard pins
  pcDebugRX       = 31
  pcDebugTX       = 30

  ' serial baud rates  
  pcDebugBaud     = 115200    
  
VAR
  long  i2cAddress, i2cSlaveCounter

OBJ
  i2cObject      : "basic_i2c_driver"
 
  'Si570Object    : "Si570Object"

  debug          : "Debug_PC"
  
  
pub Start
    ' start the PC debug object
    debug.startx(pcDebugRX,pcDebugTX,pcDebugBaud)
  
    ' setup i2cobject
    i2cObject.Initialize(i2cSCL)

    ' pause 5 seconds
    repeat 20
        debug.putc(".")
        waitcnt((clkfreq/6)+cnt)
    debug.putc(13)
  
    ' i2c state
    debug.strln(string("I2C Demo (v2)!"))

    'demo the i2c scan
    i2cScan
    waitcnt(clkfreq +cnt)

    repeat 

       
        
        ' demo the EEPROM
        if i2cObject.devicePresent(i2cSCL,eepromAddr) == true
            debug.strln(string("EEPROM Present"))
            'EEPROM_Demo
        else
            debug.strln(string("EEPROM Missing"))    
        waitcnt(clkfreq+cnt)    
         
        ' demo the Si570 Oscillator
        if i2cObject.devicePresent(i2cSCL,Si570addr) == true
            debug.strln(string("Si570 Present"))
            Si570_Demo
        else
            debug.strln(string("Si570 Missing"))    
        waitcnt(clkfreq+cnt)    
         
        
         
          
        





PRI EEPROM_Demo | eepromData, eepromLocation, ackbit
    ' demo the i2c Serial EEPROM (Microchip's 24LC512 (64kb))
    debug.strln(string("EEPROM DEMO"))
      
    ' ***** EEPROM read/Write example *****
    eepromLocation := EEPROM_Base
    eepromData := 0
    
    repeat 5
        ' write long
        eepromData += 100
        i2cObject.WriteLong(i2cSCL, EEPROMAddr, eepromLocation, eepromData)

        ' read long
        eepromData :=0
        eepromData := i2cObject.ReadLong(i2cSCL, EEPROMAddr, eepromLocation)                

        ' debug
        debug.str(string("Read Location="))
        debug.decx(eepromLocation,5)
        debug.str(string(", data="))
        debug.decx(eepromData,5)
        debug.putc(13)        
        
        ' next    
        eepromLocation +=4

        ' slowit
        waitcnt(clkfreq/20 + cnt)

    ' done
    debug.strln(string("EEPROM demo done."))        



PRI Si570_Demo | Si570Data, Si570Location, ackbit
    ' demo the i2c Serial Si570 (Microchip's 24LC512 (64kb))
    debug.strln(string("Si570 DEMO"))
      
    ' ***** Si570 read/Write example *****
    Si570Location := 7
    Si570Data := 0
    
    repeat 12
        Si570Data :=0
        Si570Data := i2cObject.ReadByte(i2cSCL, Si570Addr, Si570Location)               

        ' debug
        debug.str(string("Read Si570 Location="))
        debug.decx(Si570Location,5)
        debug.str(string(", data byte="))
        debug.decx(Si570Data,5)
        debug.putc(13)        
        
        ' next    
        Si570Location +=1

        ' slowit
        waitcnt(clkfreq/10 + cnt)

    ' done
    debug.strln(string("Si570 demo done."))

    Repeat 'Wait here



    




    

PRI i2cScan | value, ackbit
    ' Scan the I2C Bus and debug the LCD
    debug.strln(string("Scanning I2C Bus...."))
     
    ' initialize variables
    i2cSlaveCounter := 0
     
    ' i2c Scan - scans all the address's on the bus
    ' sends the address byte and listens for the device to ACK (hold the SDA low)
    repeat i2cAddress from 0 to 127
     
        value :=  i2cAddress << 1 | 0
        ackbit := i2cObject.devicePresent(i2cSCL,value)
        
        if ackbit==false
            'debug.str(string("NAK"))
        else
            ' show the scan 
            debug.str(string("Scan Addr :  %"))    
            debug.bin(value,8)
            debug.str(string(",  ACK"))                  
         
            ' the device has set the ACK bit 
            i2cSlaveCounter ++
            waitcnt(clkfreq/20+cnt)
 
            debug.putc(13)
         
        ' slow the scan so we can read it.    
        waitcnt(clkfreq/40 + cnt)

    ' update the counter
    debug.str(string("i2cScan found "))
    debug.dec(i2cSlaveCounter)
    debug.strln(string(" devices!"))

g3cwi

I eventually found that this has come up before. Will report back if the solution works.

g3cwi

Anyone setting off down this path may find the attached file makes a useful start. It is a simple manual demo of reading and writing to the Si570 via the I2C bus. It even works!

Regards

Richard
G3CWI

Cluso99

Great thanks Richard. Its on my to do list, but its a long ways down. Too many other interesting prop projects already on my plate, and not near enough time

BTW Have you seen Phils work on demodulation of RF ? He has done some great work with the prop in this arena.

g3cwi

Thanks Cluso.

I am working on "relative" frequency addressing of the chip. This seems to be pretty good for the 3500ppm range and also makes the whole control of the chip really easy (once the initial maths are done). I have settled on 50Hz steps for my application, this just requires a simple add. The hard way involves 38 bit maths plus range selection for N1 and HS_DIV which would be too much like hard work!

I have looked at Phil's work although I remain to be convinced that the Propellor is an appropriate platform for serious RF DSP (hard hat on). For much the same reasons, I am going down the AD9851/Si570 route for RF generation. I know the Propellor can do it but... I want to play to the strengths of the Prop platform.

Cheers

Richard
G3CWI

Cluso99

g3cwi: I am interested in using the prop just because I am interested in what it can do. I am also interested in the theory and the maths. But alas, I am sure it will not happen this year. So maybe I will be doing this on a Prop2.
Ray
VK2ZTZ