there mail server was ofline so i didnt get the order comfurmaton e-mail but not now this is one the microcihp sample site :
Microchip currently only accepts business sample orders in your country. We therefore cannot accept your order. We apologize for this inconvenience. If this order is for a business use, please register under your business account or contact your local Microchip sales or distribution partner to request samples directly.
BTW:
Slovakia Vs Slovenia...
Remember last week's Bush visit to Slovakia?
US news papers will never realize the difference between our two Countries. :evil:
PS: For thoose who don't understand: Slovakia is in Central Europe, not by sea as shown on map. That's Slovenia!
USB is difficult to start with even with the SIE in the newer pics. The most versatile PIC for the price seems to be the PIC16F88. It has analog and digital capabilities without getting too complicated. If you wish to interface with your PC try using the onboard USART. www.circuitblocks.com has a nice little module for converting CMOS levels to RS232. I find this much easier than adding an addional chip to my circuits. Also consider using Realterm for veiwing the rs232 data. It has many more features than hyperterminal and best of all it's free.
Perhaps you could email the sales dept. If they have any sort of confidence that you are a real person rather than a bot with 500 postal address aliases, I'm pretty sure they'll send you samples. I suspect they just don't want to make it an automatic process due to the aforementioned abuse.
The 18F252 uses a 10MHz crystal and has an internal 4x PLL to give the 40MHx clock frequency.
Also a 38.970MHz crystal is quite possibly an 'overtone' crystal, which means it's fundimental frequency will be a sub-multiple of the labelled frequency - on a microcontroller it will oscillate at it's fundimental frequency.
An instruction cycle takes 4 clock cycles, so with a 4MHz clock each instruction cycle is 1uS. On low and mid range PIC's most instructions take one instruction cycle, with a few (jumps etc.) taking two, and a few more (conditional branches) taking either one or two, depending on the outcome - they are all explained in the datasheets!.
This, by the way, is far faster than most processors, some of which take 12 or 16 clock cycles per instruction cycle, and 3 or 4 instruction cycles for some instructions!.
What are you attempting to do?, generally a 4MHz PIC is already far too fast for most jobs, you spend most of your programming slowing it down.
For an example try my first tutorials, the infamous "flashing LED's" tutorials!.
Depends on the BASIC compiler you have, but a similar thing should be possible in any dialect. If you study the tutorials I mentioned you will see that I do a similar thing in assembler!.
But you didn't answer the question!, WHY do you want to run the PIC as fast as possible?, particularly when you can use an internal oscillator on many devices?.
The BASIC section you suggested above would already completely waste something like 99.9995% of the processors time at 4MHz, so it's pretty pointless running it at 20MHz.
As I mentioned in my previous post, most of the processors time is usually taken up just wasting time - so it's mostly pointless running the PIC at unrequired high speeds - UNLESS you have a specific need for it.
There's an OLD application note at MicroChip using a very old PIC driving LED displays to give a 50MHz auto-ranging frequency counter!, and you can find a more modern version (that uses a 16C84 or 16F628 - any 18 pin PIC) from Weeder technologies that uses an LCD display. Have a look at .
They all run at only 4MHz! - increasing the clock frequency wouldn't increase the range.
or cod an 555 timer be used o produce the clock?(20kHz)
As I mentioned before, it depends on your compiler - the compiler needs to produce compatible code for the target device. The 18F252 and 16F88 are very different devices, the 18F is a high-end device, and the 16F only a mid-range device. The 18 series have a much greater range of instructions, the 16 series only have 35 instructions.
yes i mean at 20 kHz.I know 555 timers cant oscilate more than 1Mhz
I intend 555 timers to run at wery low clocks (where the PIC has noting to do most of the time)like 1kHz.
Is this posible?
and microchip has made an compiler.I think.
I think i beter get to lernig how to program there wonderful thingys.
I i found ou that bouth of my orederd PICs have low voltage in circuit programing .if i undersod right:insted of aplying 13V to the reset pin you aply ony 5V (directly Vdd)
Yes, Low voltage ICSP is useful where 13V are not available. There is also PGM pin, that has to be pulled High and a Configuration Bit to be set in order to use low voltage mode.
Can an phone charger be used to power and program the pic (it outputs 5.14V) wehithust any regulators an stuff like that.Only an 450uF cap over the output wod be to remove noise.
Il let the woris of programers,crystals and stuff like that behind (Il get the PICs in about an weak)
I shod start to lern programing basic,asembely,meaby C...