Could I have some advice on Which Pic Please?

[karenhornby]

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

[skimask]

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.

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

[Ron Marcus]

How much program/RAM space do you need?

[Acetronics2]

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

[skimask]

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.

[Acetronics2]

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