pbp to ccs

[mle]

Hello,
I have a function written in both pbp and in ccs, and I am getting different results. The function reads 2 bytes from a ds1820 temperature sensor. I am trying to read the temperature value from the scratchpad and the pbp version gives me $0030, whereas the ccs version gives $0036. I know that the pbp version is correct. The ccs version doesn't seem to respond to different temperatures correctly and I always get $0036 for the temperature value, whereas the pbp version ranges from $0030 to $0037 as I add or remove heat.

Here is the pbp version

' Read temperature from the DS1820
read1820:
For i = 1 TO 16 ' 16 bits to a word
temp = temp >> 1 ' Shift down bits
temp.15 = 1 ' Preset read bit to 1
Low DQin ' Start the time slot
TrisB.1 = 0 ' set DQin to an output
@nop ' Delay 1us at 4MHz
TrisB.1 = 1 ' set DQin back to an input
@ nop
@ nop
@ nop
@ nop
@ nop
@ nop
@ nop
@ nop
@ nop
@ nop
IF DQIn = 0 Then
temp.15 = 0 ' Set bit to 0
EndIF
PauseUs 60 ' Wait out rest of time slot
Next i
Return
End

------------------------------------------------------------------------
And this is the ccs version

long read1wire(){

int i; //counter
int result;
long temperature; //the temperature value read in from the sensor


For (i=1; i<=16; i++){
#asm
bcf PortB,1 //pull line low to start time slot
bcf TrisB,1 //set dqin to an output
nop
bsf TrisB,1 //set dqin to an input
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
#endasm
shift_right(&temperature,2,input(DQIN));

delay_us(60);
}

return temperature;
}

Can anyone suggest why the ccs one doen't work?

Thank you,
mle

[Guest]

Actually it does work! I'm just doing something wrong with the temperature pointer

[jds-pic]

hi,

can i make a few suggestions when dealing with these onewire devices?

--make a library that you can use over and over again.
--make a library that you can optimize over time, but starts off with a lot of good debugging info including intermediate output.
--make a library that can easily be debugged.
--make a library that has no dependence on the PIC clock speed used.
--make a library that has no dependence on the PIC pin used.
--make a library that does not mix ASM and C as it violates all of the above.

in summary, make (or borrow) a library.

let me help you get you started:
http://losdos.dyndns.org:8080/public/onewire/lib-onewire.html
or
http://losdos.dyndns.org:8080/public/onewire/lib-onewire.h

regards.

[Guest]

[DragonPIC]

bcf PortB,1 //pull line low to start time slot
bcf TrisB,1 //set dqin to an output


These registers are located in different banks. Remember, you are working with inline asm where you must do this manually. Also, you must make sure the bank is in back in the state you changed it from since the compiler does not know. I might be wrong with this, I never used inline asm with the pic before. Look at your list file.

another way to do this is:

[DragonPIC]

Look in the list file and make sure you will be reading each bit within the 15us slot. Also, make sure you are waiting 46us more after the 15us. Some C code can be compiled into longer or shorter asm than you think.
_________________
-Matt

[jds-pic]

when are we members going to stand up and put a stop to "guest" posting? this thread is over 2 years old but gets resurrected by a "guest", wasting a lot of folks time replying to a dead topic.

jds-pic

[PCM programmer]

To DragonPic:
You're responding to the notorious "guest", who every day dredges up
some old thread and then quotes part of it, without adding anything of
value.

To jds:
Someone will have to ask Darren to handle it.

[DragonPIC]

lol..... What a jerk. At least I learn more than something.
_________________
-Matt

[DragonPIC]

I only replied to it because I though it had to do with the "
Read temperature maximum minimum ds1624" post.
_________________
-Matt

[Darren Rook]

[mkent]

I would be in favor of letting people read all, but have to be registered and signed on in order to post.

[dyeatman]

I very definitely agree.

Many of the forums allow reading for all but require registration to post. That might help things in this forum.

I am very much in favor of eliminating/blocking "guest" posting entirely.

[PCM programmer]

[Ttelmah]

The text input 'confirmation code' system, should prevent any 'bot' from doing this. I'm afraid this is either a glitch, or a real person.

Best Wishes