My first post searching help

I having issues in connecting a small oled display purchesed from Adafruit. All the example they have are based on arduino library! The two example code I found in this forum do not work. It is a whole week I am trying to have this little thing to work without any luck. So I decided to check wich is the true address of the device I am wrking on (documentation I found says $3c; $3d ; $78 ; $7A and more) I did check all of them without any luck.
The code below is supposed to be an I2C address scanner but I am lost on how to detect the ACKNOWLEDGMENT of the device any suggestion or advice?

Code:

---



 ;----[16F88 Hardware Configuration]---------------------------------------------
#IF __PROCESSOR__ = "16F88"
  #DEFINE MCU_FOUND 1
#CONFIG
cfg1 = _INTRC_IO              ; INTRC oscillator; port I/O function on both RA6/OSC2/CLKO pin and RA7/OSC1/CLKI pin
cfg1&= _WDT_OFF              ; WDT disabled
cfg1&= _PWRTE_OFF            ; PWRT disabled
cfg1&= _MCLR_ON              ; RA5/MCLR/VPP pin function is MCLR
cfg1&= _BODEN_OFF            ; BOR disabled
cfg1&= _LVP_OFF              ; RB3 is digital I/O, HV on MCLR must be used for programming
cfg1&= _CPD_OFF              ; Code protection off
cfg1&= _WRT_PROTECT_OFF      ; Write protection off
cfg1&= _DEBUG_OFF            ; In-Circuit Debugger disabled, RB6 and RB7 are general purpose I/O pins
cfg1&= _CCP1_RB0              ; CCP1 function on RB0
cfg1&= _CP_OFF                ; Code protection off
  __CONFIG _CONFIG1, cfg1


cfg2 = _FCMEN_ON              ; Fail-Safe Clock Monitor enabled
cfg2&= _IESO_ON              ; Internal External Switchover mode enabled
  __CONFIG _CONFIG2, cfg2


#ENDCONFIG


#ENDIF


;----[Verify Configs have been specified for Selected Processor]----------------
;      Note: Only include this routine once, after all #CONFIG blocks
#IFNDEF MCU_FOUND
  #ERROR "No CONFIGs found for [" + __PROCESSOR__ +"]"
#ENDIF
LED                var PortB.3


I2C_Dev            var byte
SCL                var PortA.3                    ' I2C Clock  PortA.3
SDA                var PortA.2                    ' I2C Data  PortA.2


False              con 0
True                con 1


Flag_ack            var bit
I                  VAR BYTE
DC                  var byte
say                var byte                       


DEFINE HSER_RCSTA 90h                              ' En. s.port & cont receive
DEFINE HSER_TXSTA 20h                              ' Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 12                                ' 9600 Baud @ 32MHz, 0,16%
DEFINE HSER_CLROERR 1                              ' Clear overflow automatically
'==============================================================================


Hserout  ["System ready"]


For I = 1 to 10
Led = !Led
pause 100
next I


hserout ["Address scannining in progress..."]


for I = $08 to $77 step 2
I2CWrite SDA,SCL,I2C_Dev,[DC] 
If Flag_Ack = true then say = I     
pause 2000
Led = !Led
Next I


hserout ["Address found = ",dec say]


end

---

Thank you for the attention

Alberto

hserout ["Address scannining in progress..."]


for I = $08 to $77 step 2
I2CWrite SDA,SCL,I2C_Dev,[DC] ;Address scannining in progress.. yet you never change the address,, DC is used but never initialised
If Flag_Ack = true then say = I ; how would Flag_Ack ever change
pause 2000
Led = !Led
Next I


hserout ["Address found = ",dec say]


ps
internal pbp regbit FLAGS.5 may act like you want Flag_Ack to , but its undocumented and may not be totally reliable





try this

Code:

---

dc=0
hserout ["Address scannining in progress..."]
for I = $02 to $fe step 2
    I2CWrite SDA,I,[DC],nak 
    hserout ["Address found = ",hex2 I ,13,10]
    nak:
Next I

---

Thank you Richard for the preciuos suggestions! the program now works, tested with a working device, while is giving "Address not found!" with the oled display. At least now I know that the display is faulty and I have to order a couple of new ones if I want to finish my project.

I post the final working code for other that fighting with I2C divices could find it useful.

Code:

---

;----[16F88 Hardware Configuration]---------------------------------------------
#IF __PROCESSOR__ = "16F88"
  #DEFINE MCU_FOUND 1
#CONFIG
cfg1 = _INTRC_IO              ; INTRC oscillator; port I/O function on both RA6/OSC2/CLKO pin and RA7/OSC1/CLKI pin
cfg1&= _WDT_OFF              ; WDT disabled
cfg1&= _PWRTE_OFF            ; PWRT disabled
cfg1&= _MCLR_ON              ; RA5/MCLR/VPP pin function is MCLR
cfg1&= _BODEN_OFF            ; BOR disabled
cfg1&= _LVP_OFF              ; RB3 is digital I/O, HV on MCLR must be used for programming
cfg1&= _CPD_OFF              ; Code protection off
cfg1&= _WRT_PROTECT_OFF      ; Write protection off
cfg1&= _DEBUG_OFF            ; In-Circuit Debugger disabled, RB6 and RB7 are general purpose I/O pins
cfg1&= _CCP1_RB0              ; CCP1 function on RB0
cfg1&= _CP_OFF                ; Code protection off
  __CONFIG _CONFIG1, cfg1

cfg2 = _FCMEN_ON              ; Fail-Safe Clock Monitor enabled
cfg2&= _IESO_ON              ; Internal External Switchover mode enabled
  __CONFIG _CONFIG2, cfg2

#ENDCONFIG

#ENDIF

;----[Verify Configs have been specified for Selected Processor]----------------
;      Note: Only include this routine once, after all #CONFIG blocks
#IFNDEF MCU_FOUND
  #ERROR "No CONFIGs found for [" + __PROCESSOR__ +"]"
#ENDIF

DEFINE OSC 8                        ' define fosc
define I2C_HOLD 1                  ' define I2C type

    TrisB = %00000100              ' Set all port B pins as outputs
    TrisA = %00001100              ' Set portA.2 & portA.3 as inputs
    CMCON = 7                      ' Turn Off Comparators
    ADCON1 = 7                      ' Disable A/D converter   
    ANSEL = %00000000              ' set all analog pins to digital
    OSCCON = %01110000              ' Set PIC16F88 to 8 MHz = %01110000     

LED                var PortB.3

I2C_Dev            var byte
SCL                var PortA.3                    ' I2C Clock  PortA.3
SDA                var PortA.2                    ' I2C Data  PortA.2

False              con 0
True                con 1

Flag_ack            var bit
I                  VAR BYTE
DC                  var byte
say                var byte
 
           

DEFINE HSER_RCSTA 90h                              ' En. s.port & cont receive
DEFINE HSER_TXSTA 20h                              ' Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 12                                ' 9600 Baud @ 32MHz, 0,16%
DEFINE HSER_CLROERR 1                              ' Clear overflow automatically
'==============================================================================
Pause 10
Hserout  [13,10]
pause 10
Hserout  ["System ready",13,10]

For I = 1 to 10
Led = !Led
pause 100
next I

DC = 0
Flag_ack = false

hserout ["Address scannining in progress...",13,10]

for I = $08 to $77 step 2
I2CWrite SDA,SCL,I,[DC],NAK 
hserout ["Address found = ",hex2 I]
Flag_Ack = true     
NAK:
pause 1000
Led = !Led
Next I

If Flag_ack = false then hserout ["Address not found!",13,10]

hserout ["Address scannining completed!",13,10]

Led = False
end

---

I discover that $77 doesn't cover all devices addresses, since the scanning was unable to detect the address of a PCF8583, so exstending the scanning to $AA I got the address of this clock/calendar device.

Code:

---

for I = $08 to $AA step 2

---

Alberto