PIC Basics

[S. P. Prasad]

I would like to gain information respect to as a beginner about PIC16C6 and PIC16C7 series, namely its Architecture and instructions sets. Kindly also guide me about various series of PIC available and contrasting features among them.

 

[ivancho]

Here is a long list of all the PIC available....... check the datasheet on the ones you want to see their architecture and instructions set.

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I hope it helps

Ivancho

 

[S. P. Prasad]

Thanks a lot Ivancho. That site did contain lots of information I was seeking for. Kindly also guide me on some basics architecture concept on PIC, as there are so many variants. Do they all differ a lot from each other?

 

[ivancho]

I am not all sure what you mean by architecture............ PICs all use the Harvard Architecture, where the program and data have a seperate memory allocation. The DATA memory (RAM) consits of 8-bit registers, and the program memory is stored in 12-bit, 14-bit or 16-bit wide FLASH, EPROM or ROM. THis is where the diferent families come into place. 18FXX are the 16-bit....16FXX are the 14-bit mostly...... still you must make sure according to the datasheet.

PIC use RISC.. reduce instrunction set Computer, where each instruction is executed in one clock cycle. So a 4mHZ 16F84 will have a internal clock sycle of 1hZ....... if I remember correctly.

I hope this helps.

Ivancho

 

[S. P. Prasad]

Once again,Iancho thanks very much. Actually I wanted to know that cause there being so many variants of PIC, does each of them vary with respect to General or Special purpose register file OR that the addresses of the said registers vary with respect to its memory locations in each variant. Further more does each series has some set of specific types of instruction.
Is it that if I study any particular series of a PIC micro controller , I will be able to do code with any other PIC in series.

 

[ivancho]

Each PIC share their "base" instruction set. So once you are familiar with one programming another one is easy. There are different registers in different PIC to control the diferent ports, and built in features like ADC, UART......... so you will have to make sure you have the datasheet available to you each time, and check.

I am not an assembler user :? , simply because it takes too long to program debug, etc. I use PICBASIC PRO (PBP) which might generate a bigger code but it will save me time :wink: . I have meant to brush up my assembler but I can get to do it, because once you can do it quicly with PBP you don't want to have to spend a lot of time doing it with assembler if there is not too much of space concerns.

Hope it helps

Ivancho

 

[S. P. Prasad]

Thanks a lot Ivancho. But could you explain what you meant by saying :
"PIC use RISC. Reduce instruction set Computer, where each instruction is executed in one clock cycle. So a 4mHZ 16F84 will have a internal clock cycle of 1hZ"
.... in one of your previous replies.
Also can you facilitate me with some tech info on Basics of Programming, techniques of learning and books for beginners on PIC 16F870 series? And exactly what are the various topics I need to cover? Kindly help me, as I am completely a beginner in this domain.

 

[ivancho]

If you are a complete beginner and you want to program, you should try a BASiC compiler and a programer and get down to business.
I have 3 books for you to check out:

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The first one will give you a good initiative into the PICs and how they work and what you can do. It will make you eager for more, then the other two will help you undertand what is going on in the PIC and how assembler works on them.

PICBASIC PRO is a a good program for your programming needs. You can find it at MELABS with a whole bunch of data. Check it out.

What I meant by "4mHZ 16F84 will have a internal clock cycle of 1hZ"
was that the PIC has an internal clock divider that will make a 4hZ oscilator have a 1Hz clock. But you don't need this information quite yet. You need to familiarize with what registers the PIC have and how they are used. Example the TRIS register. The Ports and how to use them...... as you progress you will start to discover other things.....

Good Luck

Ivancho

 

[S. P. Prasad]

Many Many Thanks Ivancho. If you could facilitate me with some free online tutorials on net which explicitly or elementary explains about PIC16F870 SFR and GPR, I would be highly obliged.

Kindly answer the following questions as from my side.
What do we mean by "RISC”?
What is Flash Memory?
I would like to know that what do we mean by " Brown Out Reset"?
What does DC in DC - 20Mhz clock input or DC-200ns instruction cycle means?
What is the difference between FLASH / EEPROM memory?
What do we mean by "Eight Level deep hardware Stack”?
What do we mean by DIP,SOIC,SSOP,PLCC,QRP,I/O/P?
What do we mean when we say "PIC has 2K X 14 words Flash Program Memory”?
Thanks in advance.

 

[sbayeta]

What do we mean by "RISC”?
It means Reduced Instruction Set Computer, as oposed to CISC (Complex Instruction Set Computer). A RISC proccessor has a limited set of instructions, most of them being atomic (i.e. they execute in a single clock period). Search the web for "risc vs cisc" if you want to learn more about this.

What is Flash Memory?
It's a technology of static re-writable memories. This means you can turn of the power of the memory, and data won't get lost (like a ROM) and you can read and write the memory several times (like a RAM).

I would like to know that what do we mean by " Brown Out Reset"?
Brown out reset is an internal circuit on the PIC that resets the PIC when it detects a brownout on the supply voltage

What does DC in DC - 20Mhz clock input or DC-200ns instruction cycle means?
That means you can run your PIC at any speed you like from DC (direct current) to 20 MHz (5 mips)

What is the difference between FLASH / EEPROM memory?
Well, the differences are subtle. Read it from here:
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What do we mean by "Eight Level deep hardware Stack”?
The stack is a data structure that stores pogram instruction adresses. When you call a subrutine in your program, the proccessor must remember where it was before jumpig to the subrutine so it can resume the program execution once the subrutine finished. It "remembers" the position of the program because it saves the address of that instruction on the stack. The stack being 8 level deep means you can call a subrutine being inside other subrutine, being inside other subrutine,..... 8 times.

What do we mean by DIP,SOIC,SSOP,PLCC,QRP,I/O/P?
Those are standard chip packages (some smaller, some rectangular, surface mount, through hole, etc)

What do we mean when we say "PIC has 2K X 14 words Flash Program Memory”?
It means you can store a program as big as 2K (2048) instructions. Each instruction is 14 bits wide

 

[sbayeta]

Take a look at

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Google for the specific areas of your interests. There are literally hundreds of site with info about microcontrollers

Cheers

 

[ivancho]

You've got very good responses here. Check all this information out but don't try to memorize it all at once, it is overwhelming.
Try a small project using a PIC16F84, turn on some LED in a breadboard. The best way to learn is with practice.

If you have any more questions come back :wink:

Ivancho

 

[S. P. Prasad]

Thanks Ivancho and Sbayeta for providing me the excellent technical support. I have started developing few sample codes on PIC but badly require some more technical assistance. These are as following:

1) Kindly explain "Power-On-Reset", "WatchDog Timer", "Osicalltor Start Up Timer" and the different types of memory available in PIC?
2) Kindly explain Capture and Compare features of PIC ?
3) What do we mean by Parallel Slave Port?
4) Ofently I have seen in PIC block diagrams a backslash in the data or the address busses ? What does it actually means?
5) Kindly explain the Block diagram of PIC16F870 as provided by MicroChip?
6) If possible kindly explain me PIN wise explicit description of PIC16F870?
7) What does the 'F' and 'C' in PIC12/PIC/14/PIC16/PIC18 series stands for ?
8) Kindly if possible explain me in explicit language the features of PCL, PCLATH, INDR,FSR and others frequently used special purpose registers ?
9) I need some basic beginners sample code in order to educate myself. Can anyone facilitate me with such a set of examples?

Please help me to clear my concepts. Thanks in advance.