I2C CONFUSION, Help needed please

[Demon]

16F688 can go up to 8MHz on internal oscillator.

I'd try that before changing PIC.

Robert

[LinkMTech]

I put a test circuit together on my LAB-X4 using the PIC16F688 to talk to a 128kB FRAM.
I could feel your pain when trying to make your test program work so decided to start from almost scratch.
The TRIS statements were missing some bit assignments which are not a good thing, from what I read somewhere here by Henrik Olssen, so I put them in.
The order of CONFIG's and other setups were rearranged as well. Not really sure which fixed it but,

The end results were that it works at 4MHz and here's the program to compare with.

'
' This setup uses a PIC16F688 and a FM24V01, 128kB Nonvolatile RAM to test
' the I2CREAD/WRITE functions at 4MHz.
' 
' First: The FRAM memory is loaded with values 1~5 starting from 
' location 0 using Word size address. The values written are sequentially
' loaded into the next memory location, so only the starting address is 
' needed for this test.
' Read address = $A0
' Write address = $A1
'
' Second: The FRAM memory locations 0 thru 4 are READ in a loop then stops
' and waits the Test button on the LAB-4X to be pushed and repeats.
'
' The data was monitored with the Saleae Logic scope.
' Max clock speed measured at 4Mhz was 29kHz
'
' The DEBUG function was not used during this test
'****************************************************************

#CONFIG
ifdef PM_USED
device pic16F688, intrc_osc_noclkout, wdt_on, mclr_on, protect_off
else
__config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _IESO_OFF & _FCMEN_OFF
endif
#ENDCONFIG

'-----------------------------------------------------
PORTA=0
PORTC=0
TRISA = %00001000   ' All 8 bits assigned one way or the other
TRISC = %00000000   ' All 8 bits assigned one way or the other
CMCON0 = 7
ANSEL = 0
OPTION_REG = 128    ' PORTA pullups disabled
INTCON=128
OSCCON = %01100001  ' Oscillator set to 4MHz

DEFINE DEBUG_REG PORTC
DEFINE DEBUG_BIT 3
DEFINE DEBUG_BAUD 2400
DEFINE DEBUG_MODE 1
DEFINE OSC 4
Include "modedefs.bas"
 
'-----------------------------------------------------------
Value       VAR BYTE
WR_Addr     VAR BYTE
RD_Addr     VAR BYTE
LOC         VAR WORD    ' FRAM address must be sent as Word size
x           VAR BYTE
'------------------------------------------------------------
SCL     VAR PORTA.4     ' RA4, pin #3
SDA     VAR PORTA.5     ' RA5, pin #2
Change  VAR PORTA.3     ' Push button on LAB-X4
LED     VAR PORTA.0     ' Test LED. LOW = ON
'------------------------------------------------------------
LOC = 0             ' Start at 0
LED = 1             ' Turn LED OFF
PAUSE 1000          ' Give me a chance to start the monitor

GOSUB Load_Mem      ' Load FRAM memory locations 0~4 with values 1~5 

Main:   
    FOR LOC = 0 TO 4
        LED = 0     ' Turn ON LED, scope monitored 
        I2CWRITE SDA,SCL,$A0,[LOC],Fail1
        PAUSEUS 25  ' Paused to see on display
        I2CREAD SDA,SCL,$A1,[VALUE],Fail2
        PAUSEUS 500 ' Paused to seperate packets, viewing purpose only
        LED =1      ' Turn OFF LED
    NEXT LOC

WHILE CHange: WEND  ' Wait until button pushed
PAUSE 500           ' Cheap debounce
GOTO Main

'----------------------- Fail routines -------------------------------

Fail1:					' Try Write again
	FOR x=0 to 50
		LOW LED : PAUSE 50 : HIGH LED : PAUSE 50
	Next x
GOTO Main

Fail2:					' Try read again
	For x=0 to 5
		LOW LED : PAUSE 250 : HIGH LED : PAUSE 250
	Next x
GOTO Main

'---------------------- Load FRAM --------------------------------------

Load_Mem:
    LED = 0     ' Turn ON LED, scope monitored 
    I2CWRITE SDA,SCL,$A0,[LOC,1,2,3,4,5],Fail1
    LED = 1     ' Turn OFF LED
RETURN    
        
END

This first screenshot is from:

Load_Mem:
    LED = 0     ' Turn ON LED, scope monitored 
    I2CWRITE SDA,SCL,$A0,[LOC,1,2,3,4,5],Fail1
    LED = 1     ' Turn OFF LED
RETURN

The 2nd and 3rd from the first and last loop Reads showing the values 1 and 5 after the $A1 READ address.

[LinkMTech]

Okay decided to try the Debug and got fancy while I was at it. This can be addicting!

Here's the updated code...

'
' This setup uses a PIC16F688 and a FM24V01, 128kB Nonvolatile RAM to test
' the I2CREAD/WRITE functions at 4MHz.
' 
' First: The FRAM memory is loaded with values 1~5 starting from 
' location 0 using Word size address. The values written are sequentially
' loaded into the next memory location, so only the starting address is 
' needed for this test.
' Read address = $A0
' Write address = $A1
'
' Second: The FRAM memory locations 0 thru 4 are READ in a loop then stops
' and waits the Test button on the LAB-4X to be pushed and repeats.
'
' The data was monitored with the Saleae Logic scope.
' Max clock speed measured at 4Mhz was 29kHz
'
' The DEBUG function was used this time.
'****************************************************************

#CONFIG
ifdef PM_USED
device pic16F688, intrc_osc_noclkout, wdt_on, mclr_on, protect_off
else
__config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _IESO_OFF & _FCMEN_OFF
endif
#ENDCONFIG

'-----------------------------------------------------
PORTA=0
PORTC=0
TRISA = %00001000   ' All 8 bits assigned one way or the other
TRISC = %00000000   ' All 8 bits assigned one way or the other
CMCON0 = 7
ANSEL = 0
OPTION_REG = 128    ' PORTA pullups disabled
INTCON=128
OSCCON = %01100001  ' Oscillator set to 4MHz

DEFINE DEBUG_REG PORTC
DEFINE DEBUG_BIT 3
DEFINE DEBUG_BAUD 19200
DEFINE DEBUG_MODE 1
DEFINE OSC 4
Include "modedefs.bas"
 
'-----------------------------------------------------------
Manf        VAR BYTE[3]
Value       VAR BYTE
LOC         VAR WORD    ' FRAM address must be sent as Word size
x           VAR BYTE
'------------------------------------------------------------
SCL     VAR PORTA.4     ' RA4, pin #3
SDA     VAR PORTA.5     ' RA5, pin #2
Change  VAR PORTA.3     ' Push button on LAB-X4
LED     VAR PORTA.0     ' Test LED. LOW = ON
'------------------------------------------------------------
LOC = 0             ' Start at 0
LED = 1             ' Turn LED OFF
PAUSE 1000          ' Give me a chance to start the monitor

GOSUB Load_Mem      ' Load FRAM memory locations 0~4 with values 1~5 

Main:   
    FOR LOC = 0 TO 4
        LED = 0     ' Turn ON LED, scope monitored 
        I2CWRITE SDA,SCL,$A0,[LOC],Fail1
        PAUSEUS 25  ' Paused to see on display
        I2CREAD SDA,SCL,$A1,[VALUE],Fail2
        DEBUG "LOC = ", DEC LOC,", ","Value = ", DEC Value,13,10
        LED =1      ' Turn OFF LED
    NEXT LOC
    
    DEBUG 13,10 ' Add a space between readings
    
'   Send Reserved Slave ID $F8 and address
    I2CWRITE SDA,SCL,$F8,[$A1],Fail1
    PAUSEUS 25  ' Paused to see on display

'   Send Reserved Slave ID $F9 and address then read in 3 bytes   
    I2CREAD SDA,SCL,$F9,$A1,[Manf[0], Manf[1], Manf[2]],Fail2
    
'   Debug Manufacture and Product ID. This FRAM = 00x41x00
    DEBUG "Manf, & Product ID = ",HEX2 Manf[0],",",HEX2 Manf[1],",",_
    HEX2 Manf[2],13,10,13,10
    
WHILE CHange: WEND  ' Wait until button pushed
PAUSE 500           ' Cheap debounce
GOTO Main

'----------------------- Fail routines -------------------------------

Fail1:					' Try Write again
	FOR x=0 to 50
		LOW LED : PAUSE 50 : HIGH LED : PAUSE 50
	Next x
GOTO Main

Fail2:					' Try read again
	For x=0 to 5
		LOW LED : PAUSE 250 : HIGH LED : PAUSE 250
	Next x
GOTO Main

'---------------------- Load FRAM --------------------------------------

Load_Mem:
    LED = 0     ' Turn ON LED, scope monitored 
    I2CWRITE SDA,SCL,$A0,[LOC,1,2,3,4,5],Fail1
    LED = 1     ' Turn OFF LED
RETURN    
        
END

Now the Debug at 19.2k..