can someone help me with RCTIME

[gandora]

I have been having problem getting RCTIME to work it always results in 1 even when nothing is connected to it. I have a feeling it has something to do with the way I have analog set up, but I haven't been able to figure it out.

the code for serial output and delays is working fine. but I just get a constant stream of 1's no matter what I do. If anyone could help it would be awesome!

'---clock settings
        define OSC 8
        OSCCON = %1111110 ' sets internal osc to run at 8MHZ

'----------turn analog on porta off, and use as digital input/output
        CMCON = 0 'Comparators ON (right?)
        ANSEL = 1 'A/D ON -- Port pins all analog (I hope)
'----------

'---** Constants

rcpin var porta.3

'---**variables

rcreturn var byte

'------**main program



loop:  

'----its rctime!
pause 1000

high rcpin
pause 5 
rctime rcpin,1,rcreturn
low rcpin


'----(end rctime) shows over folks ^^



'----send serial feedback      
        serout2 porta.0, 16468, ["rc time was: ",dec rcreturn] 'call for data    
 '-----end serial feedback

goto loop   'loop forever
end

[mackrackit]

RCTIME is a digital command. All it does is measure the time it takes to discharge a capacitor to a certain voltage.

Turn analog and comparators off for the pin you are using.

[mister_e]

Hi and Welcome on the forum,
Any specific reason why you want to use RcTime? What do you want to do?

[T.Jackson]

Gotta be a Time Machine. Just has to be. This would be about the only use for RCTIME.

[mister_e]

Could be, but why i'm asking is that many use RcTime to read a POT, while using the ADC is much efficient and don't need any extra capacitor.

Let's see...

[T.Jackson]

Yeah - RCTIME is a bit inadequate for that, there's not enough span at the lower end. I think min is a few KΩ. Besides, relatively inefficient too, tying up a complex protocol for something so simple.

[skimask]

I could easily see throwing a few push buttons, each with their own resistor, on the same pin, with a parallel cap, and using RCTIME to figure out which switch was pressed.

[T.Jackson]

I could easily see throwing a few push buttons, each with their own resistor, on the same pin, with a parallel cap, and using RCTIME to figure out which switch was pressed.

That is a very good idea!

[gandora]

well, as a clarification I forgot to include. I am using the 16f88 as this projects chip. And I am trying to read a photoresistor or a pot. Mostly I am trying to carry over my knowledge of electronics from the basic stamp. And make sure I know how to do everything I had learned up till' now.

If I can do that, I can still use the books I purchased for the basic stamp as a learning tool for the pic micro. As I have decided that the stamps are not cost effective, and want to learn at a little more depth.

Also as a note, I have attempted to get it to work all digital, and on digital only ports with the same result.

If there is a better way, do tell, however I still want to know how to get the command to work. ^^ thankyou.

Hi and Welcome on the forum,
Any specific reason why you want to use RcTime? What do you want to do?

[gandora]

Gotta be a Time Machine. Just has to be. This would be about the only use for RCTIME.

Im starting with the basics but you discovered my evil plan! ^^

[T.Jackson]

As pointed out earlier, RCTIME is a digital function not analog. So you'll need to enable the port in digital mode. Your code gears the port up in analog mode. BS2 is an unpopular joke in my opinion.

[gandora]

As pointed out earlier, RCTIME is a digital function not analog. So you'll need to enable the port in digital mode. Your code gears the port up in analog mode. BS2 is an unpopular joke in my opinion.

Alright Thankyou for your help i now got it to work. For other newbs who would prefer not make a fool of themselves. The working code is below.

Thanks again. it now results in different things depending on the light. ^^

'---clock settings
        define OSC 8
        OSCCON = %1111110 ' sets internal osc to run at 8MHZ

'----------turn analog on porta off, and use as digital input/output
        CMCON = 7 'Comparators off
        ANSEL = 0 'A/D off -- Port pins all digital
'----------^^^^^^^^^^
'----------the change is in this block of code

'---** Constants

rcpin var porta.3

'---**variables

rcreturn var byte

'------**main program



loop:  

'----its rctime!
pause 1000

high rcpin
pause 5 
rctime rcpin,1,rcreturn
low rcpin


'----(end rctime) shows over folks ^^



'----send serial feedback      
        serout2 porta.0, 16468, ["rc time was: ",dec rcreturn] 'call for data    
 '-----end serial feedback

goto loop   'loop forever
end

[mister_e]

in case you're using a LDR (or high impedance analog source), i see some advantage of RCTime.. unless, i really don't. A simple transistor+few resistor + PIC adc, would be my solution if i need accuracy.

Level detector? ---> PIC Comparator

OR, PIC16F785 i've ordered a thousand of them yesterday, sOOOO much nice stuff on-board... built-in OP-AMP, 2 phase PWM + asynchronous feedback as a teaser...

NEW TOY, NEW TOY

[mister_e]

BS2 is an unpopular joke in my opinion.

To me, ANY Basic Stamp are as good as PIC16F84

But come-on... 40$ EACH

[gandora]

So you said there was a way of reading a pot in analog? Is there any chance you could give me a little synopsis of how it is done? Thankyou.

[mister_e]

Assuming your POT impedance is equal or less than the maximum recommended, you just need to feed the wiper to a PIC analog input and use the internal ADC.

PBP ADCIN is a nice start point.

[mackrackit]

This is for a 877 but it will help you get the picture.

http://www.rentron.com/PICX2.htm

Be sure to look at the speacial feature part of the data sheet for the PIC you are usinf as at this point the PIC are not "standard".

There is a RCTIME and place for everything Upgrading from the BS2, you will enjoy the built in ADC on some PICs. If you have used an external ADC with the BS2, do not try and compare this with the ones built in. End result the same but how tou get there is another story.

Have fun.

[T.Jackson]

To me, ANY Basic Stamp are as good as PIC16F84

But come-on... 40$ EACH

- you must be joking. BS2 hovers along at around 2,000 instructions p/sec. BS2 has two major short comings. 1) Overhead of the serial EEPROM which is the reason why it's so slow. 2) Cost - in Australia when BS2 was initially released it retailed for something like $100. I'd swap you a BS2 for a 16f84a any day. In fact, I'd even pay a bit of money on top. Honda Vs Ferrari basically.

[mackrackit]

- you must be joking. BS2 hovers along at around 2,000 instructions p/sec. BS2 has two major short comings. 1) Overhead of the serial EEPROM which is the reason why it's so slow. 2) Cost - in Australia when BS2 was initially released it retailed for something like $100. I'd swap you a BS2 for a 16f84a any day. In fact, I'd even pay a bit of money on top. Honda Vs Ferrari basically.

And who drives a Ferrari as there first car. The BS2 is a good way to get started. Compare to the cost of PBP or the time of learning assembly and cost of a good programmer...

And about the swap. Your on. What is you mailing address. This would make the Scouting Troop I work with very happy. Do not worry about the "bit of money on top", paying for the shipping will be fine.

[T.Jackson]

Yeah - I guess few people drive Ferraris as their first car, BS2 has its place. As far as the swap goes, I have never personally owned a BS2. I'd be more than happy to adopt some more 16f84's though. One of my old College teachers was mad into BS2. Come to think of it, he was a bit mad himself actually.

[Acetronics2]

he was a bit mad himself actually.

As one of our greatest comics ( Michel Colucci alias "Coluche" ) said :

" you always judge with your own intelligence "

Quite true.

Alain

[T.Jackson]

As one of our greatest comics ( Michel Colucci alias "Coluche" ) said :

" you always judge with your own intelligence "

Quite true.

Alain

Well, actually, I considered Adrian Down to be a very eccentric border line genius. A bit mad in his own right - many of the other students were a tad scared of him, I wasn't.

[mackrackit]

Yeah - I guess few people drive Ferraris as their first car, BS2 has its place. As far as the swap goes, I have never personally owned a BS2. I'd be more than happy to adopt some more 16f84's though. One of my old College teachers was mad into BS2. Come to think of it, he was a bit mad himself actually.

So, are you are backing out of the swap!!! ?

A man is only as good as his word.

And now that we know you have never used a BS2, I guess your comments are based on ...

[gandora]

So, are you are backing out of the swap!!! ?

A man is only as good as his word.

And now that we know you have never used a BS2, I guess your comments are based on ...

Well despite the fact that I have moved on to bigger and better things. The truth is without the BS2 I can pretty much say for sure I would have just given up before I got this far. I feel that for an initial look on microcontrollers it is a good initial investment. but I have moved on. ^^

[Pic_User]

in case you're using a LDR (or high impedance analog source), i see some advantage of RCTime.. unless, i really don't. A simple transistor+few resistor + PIC adc, would be my solution if i need accuracy.

Level detector? ---> PIC Comparator

OR, PIC16F785 i've ordered a thousand of them yesterday, sOOOO much nice stuff on-board... built-in OP-AMP, 2 phase PWM + asynchronous feedback as a teaser...

NEW TOY, NEW TOY

PIC16F785 What do you like best about them? The op-amps? What type of projects will you use them for? Should we all get a bunch just to keep up?
-Adam-

[mister_e]

Opamp is a REALLLY nice feature, i wasn't aware it was existing in one PIC.. but only voltage comparator & ADCs. Sure you could hack the voltage comparator with some feedback resistor, but my tests never give any good results... well not even close of what you should have with a op-amp.

The Asynchronous PWM feedback (and 2 phase PWM) could be nice for some DC-DC converter, Motor control and for sure, some others.

2 full independant analog comparator.. is a nice feature as well. There's also the REFCON and VRCON register which seems to add some nice stufff...

There's also something i want to test.. the built-in voltage regulator..

Don't worry, i did'nt read the whole thing really carefully

Down side.. no USART, no MSSP... Oups!

For analog stuff and power management, i think it's a really nice PIC.

Time will tell...