Ok,
what is this boot loader thing u guys are talking about. This isn't the first time i've seen it either.

I heard it when ppl were trying to pirate the satellite signal with their bootleg cards.

What is it? what does it do? what function does it play in microcontrollers? Is it something worth while learning how to do (eventually)?

 

An bootloder is an program in a PIC that can program the PIC its runing on from an EEPROM or somring else.

this works only whith PICs that have the CPU can "read/write program memory" feture

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As 'Someone Electro' says, it's a feature only available on some PIC's, basically it allows you to program the PIC without a programmer - usually via a serial port connection from a PC.

However, you still require a programmer to get the bootloader code in the PIC in the first place!.

If your design already includes a serial port (as they often do), this is a simple way to give ICSP capability - with no restrictions or limitations on your hardware design (as with normal ICSP).

I've played with a bootloader on the 16F877/876, it's very easy to use.

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Bootloaders are very useful. Check my attachment.

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Read this!
ICD2 Clone
Best PIC/DsPIC Bootloader

Read my Inchworm ICD2 review!

 

you can think of boot loader as 'operating system' or 'menu' that allows transfer of new application and selection of program you want to run. you can make it as simple as you want to or complicated as you want to.
you don't have to have it but it can make life much easier if you want to change application without need to remove chip, plug it into programmer etc. or when you want to try some new code to decide if you like it or not.
if you don't, just continue running some other (previous) program.
just imagine that your product has to be used by people who don't have programmer at hand or don't know how to use it.
for example if the controller is embeded into device such as CDROM drive or motherboard and after thousends of them are sold you figured way to improve product by using smarter code.
if you tought about it on time, you could simply release new firmware and simple instruction for end users to load it. imagine alternative which includes removing chip(s) from the unit, finding proper programming device, transfering new files etc. and what if chips are all soldered?
that would require quite good shop with experienced guys to get the job done right - not to mention assembly of something delicate and complicated.

 

im using ICSP so i dont use an boot loader.I have an conecor and i simply conect it to my breadbord,click the program button,wait a litle and unplug it

I made an conecot for it.

It wod be a a real headace having to pul it out,in the programer,out and back in the bearbord.


Bootloaders can also program an PIC from an EEPROM,EPROM or ROM memory chip that is plugen in.

this makes it wery simple for comercal devices o upgrate the program..So an serviser can come to the home,plug the memory chip i, run the PIC,plug it out and finised

so he can upgrate the firmware whith virtualy no eqipment.

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I would like to use a bootloader, or some other means to create a small trainer simular to a heathkit etw3800. I would like to be able to some switches, led's, 20 key matrix and a lcd screen to show the code and certain registers....

Am I thinking too much???

Thanks for your responses

David

 

Well one thing i found was when using low voltage circuits (3V) ICSP using a tait programmer can cause problems, like damaging the low voltage parts.

But with a MAX232 + a voltage divider + bootloader i was able to progam the chips in circuit and with my RS232 board

 

I use diodes on the Vpp and Vdd so i dont power up the whole circuit,so only the PIC gets the power

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Tait type programmers were never designed for ICSP, but there would be no problem running the Tait type designs with a 3V supply to the PIC, the open-collector buffer chip used would make it easy.

Obviously if you stick 5V on the Vdd pin of the chip it will fed 5V to the rest of the circuit, also 5V on the data and clock lines will feed through the protection diodes to the rest of the circuit as well. Vpp shouldn't be a problem, as it's designed to go higher than Vdd.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

ups!!i made an typo.I meant Vss insted of Vpp

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thanx for all the info guys.. i'll definately try that stuff out later when i get more experience.