1wiresendbyte ???

[pouchito]

Hello,

I am writing a picbasic code using the PIC SIMULATOR software.
I found out this instruction:

1WIRESENDBYTE 0xCC, 0x44

but i can't figure out what 0xCC and 0x44 means in this case

Need your help please

 

[bismark99]

Hi pouchito,

I am just now working with the ds1820 myself. I also use Pic Simulator.
If you go to page 17 of the data sheet you will see some examples of the Rom commands. 44h is when the master asks for a temp conversion, CCh is a skip rom command. This command can be better explained by the data sheet or others of this group. I don't know all I dont understand about the ds1820 right now myself.

Steve.

 

[pouchito]

Thanks a lot dear for your help.
Still have some questions about the 1wire commands

the 1wire commands are used only with temperature sensor ?
or i can use it when i have any analog 1 wire input as it name states?

I am too new to these stuff and need your help

Is it easier to use the 1wire commands or write the program without this ?

 

[bismark99]

The 1 wire input is not analog. It is serial comm line from the ds1820 to a master (your PIC). I would reccomend reading the ds1820's data sheet.

http://datasheets.maxim-ic.com/en/ds/DS18S20.pdf

and
www.maxim-ic.com/products/ibutton/ibuttons/standard.pdf

to get an understanding of this device.

From my understanding of it so far- there needs to be an exact,but simple procedure used to communicate with the ds1820. The 1 wire commands in PIC-SIM-IDE basic are used to set up the proper steps.

If you want to sence temperature with an analog device, you would use a thermistor.

Try the link:

**broken link removed**

for some ideas on this method.

Steve.

 

[gramo]

Have a look at this guide, its written in Proton+, but you can can a lite version from thier site for free (just limits the program to 50 lines)

**broken link removed**

 

[pouchito]

Thanks a lot Dude.
So what i understood is that the 1 wire command work only for the DS... temperature sensor and can't work for other analog sensor

 

[gramo]

So what i understood is that the 1 wire command work only for the DS... temperature sensor and can't work for other analog sensor

Thats about right, if your looking for a decent analog sensor, the LM35 is great! I've also got a guide on how to interface with it;

**broken link removed**

 

[pouchito]

With the LM35 i can't use the 1wire command, am i right ?

 

[pouchito]

WoW i have just checked the link, it looks great, I think it will help me a lot
Thanks dear...
I will take an idea because i m not working on a temperature sensor yet i m working on a methane sensor and i will post a new thread because i guess i still need your help if it s possible
Again Thanks a lot

 

[gramo]

That’s correct, it will still be one wire (depending on your application - see its datasheet) but the beauty of the LM35 is that each 10mV = 1 degree C, and it can handle -55 to +150 deg C.

Another benefit is that the LM35 only takes the amount of time to perform an ADC on the output, where as the DS1820 takes ~750mS on average

 

[pouchito]

Dear Gramo i have a curious sensor ,

p.s: i am just a beginner

Why sometimes , i see project where they use an amplifier before the pic yet i think in the coding we can do that by a simple math operation i guess?

 

[pouchito]

WOWWWWWWWWWWWWWWww

The site contains helpful information

You made me feel Happy on the first day of 2007

 

[gramo]

Why sometimes , i see project where they use an amplifier before the pic yet i think in the coding we can do that by a simple math operation i guess?

Your absolutely right, most PIC's can handle 10bit ADC (analogue to digital conversions) so that means they have a 0000000000 to 1111111111 resolution (that’s 0 - 1023 in decimal).

If 5V DC was they highest value on an input (i.e. 1023) then the resolution for each step would be 0.00488V DC

That’s more than accurate for most applications, but if you want to, you can improve the resolution by using an amp to make the scale of the input bigger

 

[pouchito]

Thanks again,
Waiting your help in my new post