I2CRead & I2CWrite not working as expected

[richard]

this

'*    pic16f1825      :  eprom addr =$a0   
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_OFF &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG


DEFINE OSC 32
OSCCON=$70
ANSELA=0
ANSELC=0
trisa.0=0
DEFINE I2C_SLOW 1 
ANSELA = 0
B0   Var word
X var byte
SCL var Porta.2                     
SDA var Porta.1
lata.0=1
DEFINE DEBUG_REG PORTA
DEFINE DEBUG_BIT 0      ;  if not used for pwr  
DEFINE DEBUG_BAUD 9600
DEFINE DEBUG_MODE 0     
pause 2000
Debug 13,10,"Start",13 ,10
clear
For B0 = 0 To 15 
 I2CWRITE sda,scl,$A0,B0,[99]  
 Pause 10        '
Next B0
pause 100
mainloop:
    For B0 = 0 To 15   
     I2CREAD sda,scl,$A0,B0,[X]  
     debug 13,10, dec b0, " ", dec X 
    Next B0 
    pause 1000
Goto mainloop
end

produces as expected this

Start


0 99
1 99
2 99
3 99
4 99
5 99
6 99
7 99
8 99
9 99
10 99
11 99
12 99
13 99
14 99
15 99

[CuriousOne]

Pins are configured properly, LCD also working fine.

TRISA=%00000000  'SET A TO OUTPUT   
TRISC=%00001101   
TRISB=%00011000   
ANSELH=%00000000   ' ADC OFF B
ANSEL=%000000000 ' turn off ADC
ADCON1=%10000000  'adc justify
OSCCON=%01110101  'SET FREQUENCY TO 8MHZ
WPUB=%00000000    'turn off Pullups
CM1CON0=0         'DISABLE COMPARATORS
CM2CON0=0

This code works, if there is a number [99] or whatever in the write loop
If I modify that part to look like
I2CWRITE DPIN,CPIN,$A0,B0,[B1]
or any other variable instead of B1
all zeros get written into there, instead of actual variable value.

[richard]

This code works, if there is a number [99] or whatever in the write loop
If I modify that part to look like
I2CWRITE DPIN,CPIN,$A0,B0,[B1]
or any other variable instead of B1
all zeros get written into there, instead of actual variable value.

what code ?
minimal, complete and verifiable example MCVE , its not hard

this code

'*    pic16f1825      :  eprom addr =$a0   #CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_OFF &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG


DEFINE OSC 32
OSCCON=$70
ANSELA=0
ANSELC=0
trisa.0=0
DEFINE I2C_SLOW 1 
ANSELA = 0
B0   Var word
b2 var byte
X var byte
SCL var Porta.2                     
SDA var Porta.1
lata.0=1
DEFINE DEBUG_REG PORTA
DEFINE DEBUG_BIT 0      ;  if not used for pwr  
DEFINE DEBUG_BAUD 9600
DEFINE DEBUG_MODE 0     
pause 2000
Debug 13,10,"Start",13 ,10
clear
For B0 = 0 To 15 
  b2=99+b0  
 I2CWRITE sda,scl,$A0,B0,[b2]  
 Pause 10        '
Next B0
pause 100
mainloop:
    For B0 = 0 To 15 
  
     I2CREAD sda,scl,$A0,B0,[X]  
     debug 13,10, dec b0, " ", dec X 
    Next B0 
    pause 1000
Goto mainloop
end

produces as expected

Start

0 99
1 100
2 101
3 102
4 103
5 104
6 105
7 106
8 107
9 108
10 109
11 110
12 111
13 112
14 113
15 114

[CuriousOne]

The code which I've posted, which writes 99 into eeprom.
I replace 99 with any other value - it works.
I put variable name into brackets - it writes zeroes into eeprom.
no matter what type of variable or what value do it has.

[CuriousOne]

Here is full complete code.

;----[16F886 Hardware Configuration]--------------------------------------------
#CONFIG
cfg1 = _INTRC_OSC_NOCLKOUT    ; INTOSCIO oscillator: I/O function on RA6/OSC2/CLKOUT pin, I/O function on RA7/OSC1/CLKIN
cfg1&= _WDT_ON                ; WDT enabled
cfg1&= _PWRTE_OFF             ; PWRT disabled
cfg1&= _MCLRE_OFF             ; RE3/MCLR pin function is digital input, MCLR internally tied to VDD
cfg1&= _CP_OFF                ; Program memory code protection is disabled
cfg1&= _CPD_OFF               ; Data memory code protection is disabled
cfg1&= _BOR_OFF               ; BOR disabled
cfg1&= _IESO_ON               ; Internal/External Switchover mode is enabled
cfg1&= _FCMEN_ON              ; Fail-Safe Clock Monitor is enabled
cfg1&= _LVP_OFF               ; RB3 pin has digital I/O, HV on MCLR must be used for programming
cfg1&= _DEBUG_OFF             ; In-Circuit Debugger disabled, RB6/ICSPCLK and RB7/ICSPDAT are general purpose I/O pins
  __CONFIG _CONFIG1, cfg1


cfg2 = _BOR40V                ; Brown-out Reset set to 4.0V
cfg2&= _WRT_OFF               ; Write protection off
  __CONFIG _CONFIG2, cfg2


#ENDCONFIG


'chip configs
TRISA=%00000000  'SET A TO OUTPUT   1=input
TRISC=%00001101   'set half C for in/out
TRISB=%00011000   'set PortB to output
ANSELH=%00000000   ' ADC OFF B
ANSEL=%000000000 'configure PortA as digital except first 2
ADCON1=%10000000  'adc justify
OSCCON=%01110101  'SET FREQUENCY TO 8MHZ
WPUB=%00000000    'turn off Pullups
CM1CON0=0         'DISABLE COMPARATORS
CM2CON0=0         'SAME HERE
'CCP1CON=%01000000 ' configure pwm
'PSTRCON=%00010110 'disable C pwm


DEFINE OSC 8   
DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 50
'lcd config
pause 200
' Set LCD Data port 
DEFINE LCD_DREG PORTC  
DEFINE LCD_DBIT 4  
DEFINE LCD_RSREG PORTB  
DEFINE LCD_RSBIT 0  
DEFINE LCD_EREG PORTB  
DEFINE LCD_EBIT 1  
DEFINE LCD_BITS 4  
DEFINE LCD_LINES 2  
DEFINE LCD_COMMANDUS 1500  
DEFINE LCD_DATAUS 44
define i2c_slow 1




DPIN Var PORTA.2       ' I2C data pin
CPIN Var PORTA.1       ' I2C clock pin
B   Var word
B1   Var byte
B2   Var byte


For B = 0 To 15 
  b1=99+b 
 I2CWRITE dpin,cpin,$A0,B,[b1]  
 Pause 10        '
Next 
pause 100


mainloop:


   For B = 0 To 15   
     I2CREAD DPIN,CPIN,$A0,B,[b2]  
     lcdout $fe, $1, dec b, " ", dec b2 
     pause 1000
   Next 
 
   Goto mainloop
 
   End

And funny thing happens - the returned value of B2, as shown on display, is 114! for all 16 locations.
looks like 1st loop executed before writing to EEPROM ?

[CuriousOne]

Maybe read routine is faulty?

[CuriousOne]

yes it is read routine - it reads eeprom only once.

[richard]

works perfectly on simulator

had to increase some delays for slow old lcd
pause 1000
' Set LCD Data port
DEFINE LCD_DREG PORTC
DEFINE LCD_DBIT 4
DEFINE LCD_RSREG PORTB
DEFINE LCD_RSBIT 0
DEFINE LCD_EREG PORTB
DEFINE LCD_EBIT 1
DEFINE LCD_BITS 4
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 2000
DEFINE LCD_DATAUS 44
lcdout $fe, $1, "ready " ;added to prove lcd working
pause 1000