Could I have some advice on Which Pic Please?

Sorry to be a right pain in people's butts,
I had many problems when i first started working with PIC's and you kind people helped me tremendously thanks :)
However now I've done all the code and got everything working, I've realised I'm using way too big of a PIC 16F877A with too much wastage on it

What I need to know is :
Whats the best pic that will do the following:
compatible with a DS18B20 for temperature measurement
4 input pins (simple high or low inputs)
4 output pins (simple high or low outputs through transistor switch to operate relay)
6 Pins for an LCD (4 bit mode)
gonna be working with an 8Mhz resonator because no crucial timings involved.
NO critical measurments being made, just switching outputs depending on input selections
Will be be programmed with an ICD2

If anyone has any ideas on what PIC would be best to use so hardly any pins are wasted (as small a pic as possible) could they let me know please
Also and this is a very big hope in my part :)
Does anyone know the defines to use with PBP and ICD2 for whatever PIC chip they are suggesting?

It's not important I can always just use the 16F877A I've got working, but this way not only do I make the chip smaller and less wastage, but I learn the differences between programming the two

OH and also what would be exreeeeemely hand would be the config needed to set the ports to straight inputs and or outputs, I can never work that one out

Always hopeful :)
Karen

Quote:

Originally Posted by karenhornby

Whats the best pic that will do the following:
compatible with a DS18B20 for temperature measurement

It's not the PIC that fullfills the requirements for being compatible with the DS18B20...it's the keyboard operator.

Quote:

4 input pins (simple high or low inputs)
4 output pins (simple high or low outputs through transistor switch to operate relay)
6 Pins for an LCD (4 bit mode)
gonna be working with an 8Mhz resonator because no crucial timings involved.

http://www.microchip.com/ParamChartS...g=en&pageId=74

A 16F628A handles everything but the 8Mhz (has 4Mhz internal)
Once you need an 8Mhz internal and small, as in 18 pin package,
http://www.microchip.com/ParamChartS...g=en&pageId=74
2 pins power/ground, internal 8Mhz, 14 I/O + a pin for the DS18B20...
18F1220/1230/1320/1330...
No pins wasted...small package...

It's all in the parametric search pages at www.microchip.com

How much program/RAM space do you need?

Hi, Karen

with the external Xtal or reso ... 16F628/648 will be unbeatable !!!
with internal 8Mhz clock ... 16F88 or 16F819 ...

18F1320 ... I had small problems with mine ( no more than 20 reprogrammings available , EEPROM single location programming ... FALSE !!! Works well ONLY with more than two writings ... )

searchtool here also:

http://melabs.picbasic.com/Scripts/perl/picsearch.pl

Alain

Quote:

Originally Posted by Acetronics

18F1320 ... I had small problems with mine ( no more than 20 reprogrammings available , EEPROM single location programming ... FALSE !!! Works well ONLY with more than two writings ... )

Had problems with my 18F1320's also using a Warp13a awhile back. Had to add an extra .1uf cap across Vdd/Vss, worked like a champ. Have been using PICKIT2 to do them the same way. Haven't tried it without the extra .1uf cap's though. Will do over this weekend and let you know.

Hi, Ski

I've tried Picstart, ICD2, PicFlash and a programmer from one of our Magazines ( a serious one ! Lol ! ) ...

Always the same answer ... only erasing seems to work.

a second chip had refused Picstart programming for a moment ... and with the 8.0 MPLAB release, It miraculously came back to life ...
I didn't insist further and "locked" it firmly on a PCB !!!

Capacitor and/or 1K have been tried with no appearing result ...

Now, I just program them from blank and send the PCB assembled ...

µChip has been unable to tell me something about that ... and the error sheet didn't show anything suspect ...
The memory issue needed to use the Brownout ... very,very bad idea aboard something flying !!!

Alain

karenhornby, I would suggest using an 18F2620 as there are enough pins to do what you want as well as 2 CCP modules a voltage reference, comparator and you can run it at 40Mhz. if necessary. I have used these parts for many products over the last year and 1/2 and have had great success. If you are planning on laying out a pc board it will give you some extra pins to use in the future... It also has 4 timers and enhanced capture/compare for use with an H bridge later on if needed...

Dave Purola,
N8NTA

Thanks guys :)
All pretty helpful, and I never knew abt the reference page to look them up.
The program I've written is 8k (the hex file is) and the reason I havent even considered the 18 series is i was as few pins as possible and dont need any complicated maths functions or add ons. It's going to be a simple switching circuit depending on what inputs are high will then determine what outputs go high and whats displayed oin the LCD display, it's that simple
I actually never considered an internal reference it would cut component count down using internal too thanks :)
The only problem stopping me using the 16F628A as suggested is the program size, i could add eeprom i guess but it's simpler to use a different pic than use more components.
My idea is to make the project as small and compact as possible but still using discreet components and NOT smd's.

Looks like it may have to be the 16F877A
Thanks Everyone :)
and Hi Dave, de Karen M3ZZZ

Quote:

Originally Posted by karenhornby

The only problem stopping me using the 16F628A as suggested is the program size, i could add eeprom i guess but it's simpler to use a different pic than use more components.

You know what else might be even easier would be to post the code and see if any of us could possibly help you optimize it a bit more and make it take up less code space :)

Quote:

Originally Posted by skimask

You know what else might be even easier would be to post the code and see if any of us could possibly help you optimize it a bit more and make it take up less code space :)

Sorry didn't do it b4 as I didn't want to ask for too much help.
JUST changed the code to get rid up unneeded pins, i.e led o/p's that wont be on the final version it will only use the lcd
What I'd like to do more neatly is have it so if PORTD.1 is pressed twice within the space of 2 seconds the program jumps to STOP1
If PORTD.1 is ONLY pressed once then it jumps to PURGING:
I'm sure there is a simpler way to do it than I've used.

Oh Acetronics thanks :) I've actually deleted quite a few lines of code and actually have no idea what size it assembles to at the moment as the computer I'm using at the moment doesn't have a complier on it
BUT when I compiled the code that you saw, the hex file was 8K (7.28K to be exact)
Maybe I did things wrong, I dont know i'm still extremely new to this, I was using the Mikroe easypic5 when i designed the circuit, now I've got rid of that and am going to make up a circuit board with just the parts needed and program it direct using the ICD2 (hopefully :) )

Code:

'**************************************************************** '* Name : Oil Control.BAS * '* Author : [select VIEW...EDITOR OPTIONS] * '* Notice : Copyright (c) 2008 [KarenH] * '* : All Rights Reserved * '* Date : 06/05/2008 * '* Version : 1.0 * '* Notes : * '* : * '**************************************************************** Define LOADER_USED 1 @ DEVICE pic16F877a,HS_OSC,WDT_OFF,LVP_OFF ' Define various stuff DEFINE OSC 8 DEFINE LCD_DREG PORTB ' Set LCD Data port DEFINE LCD_DBIT 0 ' Set starting Data bit (0 or 4) if 4-bit bus .7 DEFINE LCD_RSREG PORTB ' Set LCD Register Select port DEFINE LCD_RSBIT 4 ' Set LCD Register Select bit DEFINE LCD_EREG PORTB ' Set LCD Enable port DEFINE LCD_EBIT 5 ' Set LCD Enable bit i.e, PORTE.4 DEFINE LCD_BITS 4 ' Set LCD bus size ot 4 bit Upper Nibble (4 or 8 bits) DEFINE LCD_LINES 2 ' Set number of lines on LCD to 4 Lines DEFINE LCD_COMMANDUS 2000 ' Set command delay time in us DEFINE LCD_DATAUS 50 ' Set data delay time in us ' Allocate variables command var byte ' Storage for command i var byte ' Storage for loop counter temp var word ' Storage for temperature DQ var PORTA.5 ' Alias DS1820 data pin DQ_DIR var TRISA.5 ' Alias DS1820 data direction pin ADCON1 = 7 ' Set PORTA and PORTE to digital Pause 500 ' Wait for LCD to start Lcdout $FE,1," All Circuits", $FE,$C0, " Funtioning OK " ' Display sign-on message Pause 3000 'Wait 3 seconds going any further ' Mainloop to read the temperature and display on LCD mainloop: Gosub init1820 ' Init the DS1820 command = $cc ' Issue Skip ROM command Gosub write1820 command = $44 ' Start temperature conversion Gosub write1820 Pause 500 ' Wait 0.5 seconds for conversion to complete Gosub init1820 ' Do another init command = $cc ' Issue Skip ROM command Gosub write1820 command = $be ' Read the temperature Gosub write1820 Gosub read1820 ' Display the decimal temperature IF PORTC.0 = 0 AND PORTC.3 = 0 then lcdout $FE,1," Diesel", $FE,$C0,"Outside ", $fe, $C9, dec (temp >> 1), ".", dec (temp.0 * 5), $DF, "C": LOW PORTE.0: LOW PORTE.1 IF PORTC.0 = 1 AND PORTC.3 = 0 then gosub Tempcheck IF PORTC.0 = 0 AND PORTC.3 = 1 then gosub Tempcheck If PORTC.0 = 1 AND PORTC.3 = 1 then gosub Oil IF PORTD.1 = 1 Then GOSUB purging Goto mainloop ' Do it forever Stop1: LOW PORTE.0 LOW PORTE.1 LCDOUT $FE,1," MANUAL",$FE,$C0," Diesel OVERRIDE" while PORTD.1=0 'OVERRIDE COMMAND to MANUALLY switch back to DIESEL i.e. if veg oil runs out wend pause 1000 'so a very quick button press is NOT recognised and the program stays paused Goto Tempcheck OIL: LCDOUT $FE,1," Veg-Oil", $FE,$C0,"Outside", $fe, $C9, dec (temp >> 1), ".", dec (temp.0 * 5), $DF, "C" HIGH PORTE.0 'Diesel Solenoid HIGH PORTE.1 'OIL Solenoid return Tempcheck: lcdout $FE,1," TEMP LOW", $FE,$C0,"Still on DIESEL" LOW PORTE.0: LOW PORTE.1 return Purging: LCDOUT $FE,1," PURGING Please",$FE,$C0," WAIT" HIGH PORTE.0 'Diesel Solenoid LOW PORTE.1 'Oil Solenoid Pause 60000 'set delay of purge here 60 seconds gosub Stop1 Goto mainloop ' Initialize DS1820 and check for presence init1820: Low DQ ' Set the data pin low to init Pauseus 500 ' Wait > 500us DQ_DIR = 1 ' Release data pin (set to input for high) Pauseus 100 ' Wait > 100us If DQ = 1 Then Lcdout $fe, 1, "DS1820 not present" Pause 500 Goto mainloop ' Try again Endif Pauseus 400 ' Wait for end of presence pulse Return ' Write "command" byte to the DS1820 write1820: For i = 1 to 8 ' 8 bits to a byte If command.0 = 0 Then Gosub write0 ' Write a 0 bit Else Gosub write1 ' Write a 1 bit Endif command = command >> 1 ' Shift to next bit Next i Return ' Write a 0 bit to the DS1820 write0: Low DQ Pauseus 60 ' Low for > 60us for 0 DQ_DIR = 1 ' Release data pin (set to input for high) Return ' Write a 1 bit to the DS1820 write1: Low DQ ' Low for < 15us for 1 @ nop ' Delay 1us at 4MHz DQ_DIR = 1 ' Release data pin (set to input for high) Pauseus 60 ' Use up rest of time slot Return ' Read temperature from the DS1820 read1820: For i = 1 to 16 ' 16 bits to a word temp = temp >> 1 ' Shift down bits Gosub readbit ' Get the bit to the top of temp Next i Return ' Read a bit from the DS1820 readbit: temp.15 = 1 ' Preset read bit to 1 Low DQ ' Start the time slot @ nop ' Delay 1us at 4MHz DQ_DIR = 1 ' Release data pin (set to input for high) If DQ = 0 Then temp.15 = 0 ' Set bit to 0 Endif Pauseus 60 ' Wait out rest of time slot Return End

Hi, Karen ...

Quote:

The program I've written is 8k (the hex file is)

The sample you gave compiles ... 1315 Words

did I miss something ???

Alain

Changed the code previously posted to get rid of unused functions

That fits into a 16F628a whithout any problem ... then.

may we consider the subject solved ???

you can easily save some more room, simply replacing "high x " and "Low y " by " x = 1 " and " y = 0 "

Alain

Code:

Define LOADER_USED 1

If you don't need it in the end product, would save some space here...

Code:

IF PORTC.0 = 0 AND PORTC.3 = 0 then lcdout $FE,1," Diesel", $FE,$C0,"Outside ", $fe, $C9, dec (temp >> 1), ".", dec (temp.0 * 5), $DF, "C": LOW PORTE.0: LOW PORTE.1 IF PORTC.0 = 1 AND PORTC.3 = 0 then gosub Tempcheck IF PORTC.0 = 0 AND PORTC.3 = 1 then gosub Tempcheck If PORTC.0 = 1 AND PORTC.3 = 1 then gosub Oil

The If/AND/Then takes up more space than consecutive If/Then's...

Code:

IF PORTC.0 = 0 then If PORTC.3 = 0 then lcdout $FE,1," Diesel", $FE,$C0,"Outside ", $fe, $C9, dec (temp >> 1), ".", dec (temp.0 * 5), $DF, "C": LOW PORTE.0: LOW PORTE.1 endif endif

Code:

For i = 1 to 8 ' 8 bits to a byte

For i = 0 to 7 would save a few more bytes

Code:

For i = 1 to 16 ' 16 bits to a word[/B]

Same thing here.... For i = 0 to 15

Just some tips for future use... :)

Many thanks Gents :)
You're all stars (in my eyes)
and yes subject closed.
Thanks again