I2C CONFUSION, Help needed please

[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.

[Demon]

I thought I saw 9 bits used from control in the datasheet you linked.

Maybe you're supposed to use a word and ignore the other 7 bits? Or that could be handled by PBP for I2C?

Do you get only a byte back, word, multiple bytes?

Your circuit does make address 0 right?

(just throwing ideas at you)

Robert

[FromTheCockpit]

Steps Taken:

1) Configuration changed: _INTRC_OSC_NOCLKOUT
2) Made 16f688 run at 8MHz : OSCCON=%01110001
3) Commented DEFINE I2CSLOW 1
4) Value changed to BYte (then to word again)

I get a byte back from the device (from what I have understood). Yes there is an address 0 in the device. I should get back chip ID i.e-'2E' as per the datasheet.

Still no Luck.

[LinkMTech]

I couldn't find detailed info on the Write/Read bit of the device address. But I will guess it is bit 7.
You need to Write to the device first using the address with the "Write" bit set.
$1B or %00011011 becomes $9B or $10011011

Without confirming the proper syntax of the commands, here's something off the top of my noodle:

This will cover steps 1~4 of Section 4.3.2 of the datasheet

I2CWRITE SDA,SCL,[Addr,Loc,]  ' Addr plus Write bit = $9B

This will cover steps 5~7 of Section 4.3.2 of the datasheet

I2CREAD SDA,SCL,[Addr,Loc]   ' Addr plus Read bit = $1B

Putting it together should get you moving in the right direction.

I2CWRITE SDA,SCL,[Addr,Loc,]  ' Addr plus Write bit = $9B
I2CREAD SDA,SCL,[Addr,Loc]   ' Addr plus Read bit = $1B

Here's a note to myself that might come in handy too:

[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.