KansaiRobot
Member
Hello and thanks always
I would appreciate your help on a problem I have
I have succesfully programmed a board containing a PIC18F2553 with 20MHz crystal and 22pF capacitors in it
https://akizukidenshi.com/img/goods/C/K-08010.jpg
now I am trying to do the same with a PIC 18F2550 but this time I will be building my board.
First trying it on a breadboard I am using a 24MHz crystal
https://pdf1.alldatasheet.com/datasheet-pdf/view/70113/KSS/HC-49U-S.html
with either 18pF or 20pF capacitors.
I of course, according to the datasheet changed the PLLDIV settings from 5 (for 20MHz) to 6 (24MHz) so that the PLL part gets the required 4MHz.
The thing is that the PC does not recognize this as a USB device. First it was recognized as an "unknown device"
Now it doesnt even recognize there is something attached to it...
At first I thought maybe the crystal in the breadboard was not working well, but I programmed a non-USB program in the pIC and it worked well (although much faster than my previous internal oscillator experience)
Now my guess is that maybe the crystal is not providing the required frequency.
1) How can I make sure the frequency is the correct one
2) I am confused, what is the difference between a crystal and a crystal oscillator?
3) if I use something like
**broken link removed**
do you think it would be better? No capacitors to use
4) what is an "external clock" and how do I get one just in case
Any possible help on this will be greatly appreciated.
I would appreciate your help on a problem I have
I have succesfully programmed a board containing a PIC18F2553 with 20MHz crystal and 22pF capacitors in it
https://akizukidenshi.com/img/goods/C/K-08010.jpg
now I am trying to do the same with a PIC 18F2550 but this time I will be building my board.
First trying it on a breadboard I am using a 24MHz crystal
https://pdf1.alldatasheet.com/datasheet-pdf/view/70113/KSS/HC-49U-S.html
with either 18pF or 20pF capacitors.
I of course, according to the datasheet changed the PLLDIV settings from 5 (for 20MHz) to 6 (24MHz) so that the PLL part gets the required 4MHz.
The thing is that the PC does not recognize this as a USB device. First it was recognized as an "unknown device"
Now it doesnt even recognize there is something attached to it...
At first I thought maybe the crystal in the breadboard was not working well, but I programmed a non-USB program in the pIC and it worked well (although much faster than my previous internal oscillator experience)
Now my guess is that maybe the crystal is not providing the required frequency.
1) How can I make sure the frequency is the correct one
2) I am confused, what is the difference between a crystal and a crystal oscillator?
3) if I use something like
**broken link removed**
do you think it would be better? No capacitors to use
4) what is an "external clock" and how do I get one just in case
Any possible help on this will be greatly appreciated.