I2C CONFUSION, Help needed please

[FromTheCockpit]

I am trying to communicate with an I2C device. I have done almost everything I could think of but it is not working. The manual mentions stuff but not exactly matching with the datasheet of the device. The device datasheet mentions something about ACK/NACK which the pbp manual does not mention even once. On top my lack of understanding of I2C has left me with no other option to ask here about what I am doing wrong.

What I have done:
I have tried the following commands:
Value var byte
I2CREAD SDA,SCL,%000110100,0,[Value] ' Tried this
I2CREAD SDA,SCL,$1B0,0,[Value] ' Tried this
I2CREAD SDA,SCL,$1B,0,0,[Value] ' Tried this

Then When I do this:
debug HEX Value ' I am expecting '2E' on my screen. But I am not getting it.
(Location Zero will read 2E in the device)

I attach the section explaining the I2C from the datasheet. The device address is $1B.
Many thanks in advance

(Using 16F688 @ 4 MHz)

[rsocor01]

Did you put the two pull-up 4.7k resistors in the SDA and SCL lines?

Robert

[rsocor01]

Also, you don't need to worry about anything that you highlighted in red. The I2CREAD and I2CWRITE commands take care of that for you.

Robert

[FromTheCockpit]

Did you put the two pull-up 4.7k resistors in the SDA and SCL lines?

Robert

Yes, pull ups are there @ 3.2k.
I tried the statement : I2CREAD SDA,SCL,$1B,0,[VALUE] (is it correct? because I don't had any luck)

[FromTheCockpit]

My Code is this:

Include "modedefs.bas"
DEFINE OSC 4

#CONFIG
ifdef PM_USED
device pic16F688, intrc_osc_noclkout, wdt_on, mclr_on, protect_off
else
__config _XT_OSC & _WDT_OFF & _PWRTE_ON & _MCLRE_ON & _CP_ON & _CPD_ON & _BOD_ON & _IESO_ON & _FCMEN_ON
endif
#ENDCONFIG

DEFINE DEBUG_REG PORTC
DEFINE DEBUG_BIT 3
DEFINE DEBUG_BAUD 2400
DEFINE DEBUG_MODE 1

DEFINE I2C_SLOW 1
'DEFINE I2C_HOLD 1
'-----------------------------------------------------
PORTA=0
PORTC=0
TRISA = %000100
TRISC = %110000
CMCON0 = 7
ANSEL = 0
OPTION_REG = 128
INTCON=128
'-----------------------------------------------------
Value Var word
'------------------------------------------------------------
SCL Var PortC.5
SDA Var PortC.4
Change Var PortA.2
LED Var PortC.0
'---------------------------------------------------------
Pause 500
DEBUG "Start......",13,10
value=0

Main:
High Led : Pause 1000: Low Led : PAUSE 1000

I2CREAD SDA,SCL,$1B,0,[VALUE],Fail
PAUSE 25
DEBUG HEX Value,13,10
PAUSE 250
DEBUG "Done....",13,10
Goto Main

Fail:
toggle portc.2
goto main

PortC.2 keeps toggling along with normal LED.

I have also attached the device datasheet. I really appreciate the help in this.

[Demon]

From PBP manual about I2CREAD:

"Constants should not be used for address..."

Don't know if this can help.

Robert

[FromTheCockpit]

From PBP manual about I2CREAD:

"Constants should not be used for address..."

Don't know if this can help.

Robert

I added two bytes - Addr & Loc
Addr=$1B
Loc=0

Sent - I2CREAD SDA,SCL,Addr,Loc,[Value],Fail

No Luck

'-----------
What is also confusing me is the control byte in the manual, the device datasheet does not mention any control byte.
I have an address $1B which I am sending as control and location in the device is being sent as Address according to the manual.

[aratti]

The device you are using is a fast mode device (400 khz) so you have to remove the "DEFINE I2C_SLOW 1" and very likely you have to increase your clock speed (4 MHz could be too slow). Also change the variable into byte (you are using word).

Good luck

Al.