On Sat, Mar 23, 2002 at 03:31:31PM -0600, Pic Dude wrote: > A slightly different perspective... > > As a rookie myself, I believe that the 16F84 is a great chip to > start with, because there are lots of sample projects/code out on > the web to pick things up quickly. You can just copy, compile > and test, then experiment with the code. At a few bucks each, > cost isn't much of a factor. Two things. With a couple of very small exceptions the code works as is. Here are the exceptions: * If you're using PORTA you must turn the analog comparators off. * You must move the beginning starting address of variables because of the new special purpose registers. * Be aware that the last 16 bytes of every bank is shared. This is actually an advantage for interrupt code. > > And if they're becoming obsolete, then perhaps they're less > than a few bucks now? PICs have always had a small cost. But the 16F628 are about 60% the price of a 16F84A. > > Get a very simple 16F84 programmer or get one that will handle > 16F84 + others you think you will need. Probably not as simple as a low voltage programmer for a 16F628 or 16F877. At minimum you'll need either a split power supply or a regulator to drop the 13V to 5V. Then you'll need an additional switch to switch between 13V and 0V on MCLR. My Trivial LVP programmer is trivial for a reason. > I built a simple Tait > programmer and there was a simple wiring difference to handle > the 16F872's when I started playing with those. Agreed. In fact it's little more than a different wiring harness. Now to the 16F628's advantages: * More of every type of memory. * Built in INTRC oscillator. For blinkly led type projects, you need nothing more than the chip and the LED. No external RC, resonator, or crystal. * PWM, hardware USART, and capture compare modules. * 3 timers. Very handy. * The ability to get up to 3 extra I/O pins. Have you had the 16F84 project that would have been perfect if you could get just one extra input? Well with the 16F628 you can because MCLR, OSCIN, and OSCOUT can all be utilized as I/O. * The aforementioned ability to be low voltage programmed. * Runs 16F84 code essentially unmodified. * It's cheaper. 'nuff said. In fact the only one feature that it's missing is the ability to self program its program memory like the 16F87X series. I was a long time 16F84 user. The lack of hardware USART and timers really cramps the 16F84's style. Programmers often have to go through contorsions just to resolve simple issues where more hardware could easily resolve the problem. the 16F628 still lets beginners start off simple and small, but has the muscle to tackle bigger problems in a more straightforward fashion. The 16F84 has no case. That's why Microchip themselves are trying to price it into retirement. BAJ > > Good beginning info and books... > http://www.piclist.com/techref/piclist/begin.htm > > Cheers, > -Neil. > > > ----- Original Message ----- > From: "Byron A Jeff" > To: > Sent: Saturday, March 23, 2002 2:23 PM > Subject: Re: [PIC]: Please help rookie with these two questions > > > > On Sat, Mar 23, 2002 at 02:01:45PM -0500, Jim Martin wrote: > > > First: What beginner's book do you recommend for entry level PIC > > > programming for the 16F84? > > > > It's best to skip the 16F84. Microchip has pretty much succeeded in > obsoleting > > it with the features and price of the 16F627 and 16F628 chips. It's better > > to start there. > > > > I don't have a book recommendation for you unfortunately. There are any > number > > of online tutorials that'll get you started. I'm partial to Myke Predko's > > online stuff. You can find a couple of introductory articles here: > > > > http://www.rentron.com/Myke3.htm > > http://www.rentron.com/Myke5.htm > > > > There are also several dozen other PIC related articles on the site here: > > > > http://www.rentron.com/pic.htm > > > > I'd like to add a couple of comments related to the 16F84 to 16F627/8 > upgrade. > > First is that if the application isn't time sensitive (such as an > asyncronous > > serial interface) that the internal RC oscillator of the 16F627/8 preludes > > having to use an external oscillator or resonator. Next is that one must > be > > acutely aware that one of the best new features of the 16F627/8 is the > onboard > > hardware USART. This means that one doesn't have to implement software > UARTs > > by hand. I find that a lot of 16F84 tutorials spend a lot of time > discussing > > how to build software serial routines for RS-232. The next thing is that > > the 16F627/8 family along with the 16F87X family are low voltage > programmable > > so very cheap and simple programmers can be utilized to get started > quickly. > > My Trivial Low Voltage Programmer (TLVP) is a $10, afternoon project > that'll > > get you in the game quickly. Last on my list is that for programming > hardware > > USART the best software/tutorial going is Fr. Thomas McGahee's PICUART > code. > > I've seen problems dowloading it from his site > (http://mcgahee.freeservers.com) > > so I've made a copy available from my PIC site where the TLVP lives: > > > > http://www.finitesite.com/d3jsys > > > > Also you can find a description os Myke's book "Programming and > Customizing > > PICmicro Microcontrollers" on his site at http://www.myke.com where he has > > a online chapter for your perusal. > > > > > > > > Second: Is the 16F876 code-compatible with the 16F84? Just wondering > if I > > > should start with the '876 instead of the F84. > > > > I think you can pretty much get a consensus not to start with the 16F84. > Yes > > the 16F87X series is code compatible with the 16F84 and will port over > with > > a very few caveats such as variable starting address and that PORTA starts > > in analog mode instead of digital mode. > > > > But starting with the 16F84 means playing catchup later. There's much less > of > > a jump from the 16F62X family to the 16F87X chips. > > > > Hope this gives you some insight. > > > > BAJ > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > > > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! 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