18F2550 Bootloader

eng.mohamedtoumi · Joined: 13 Jan 2018 Posts: 23 Location: Tun

Hello ...
Can anybody provide me with a bootloader for MCU 18F2550 compatible with Pic c ccs software ??!
If not, how can i burn the hex file to the MCU without Pickit ?
Thank you

temtronic · Posted: Wed May 16, 2018 10:11 am

CCS probably has a bootloader in the examples folder and searching this and the code library forum should get some hits....
As for burning a PIC without a PICkit, there are several 'homemade' burners using ICSP pins but I've seen Pickit3s sell for maybe $25USD. A proper burner should always work...homemade ,well a minor wiring error could cost you a week's work finding the fault....
Jay

eng.mohamedtoumi · Joined: 13 Jan 2018 Posts: 23 Location: Tun

is there is any way to program 18F2550 Via Usb without any burner ... ?!

temtronic · Posted: Wed May 16, 2018 10:45 am

No. As shipped all PICs have NOTHING in their memory. You need at the very least to 'burn' in a 'bootloader', in order to then 'download' your real program. A bootloader is typically accessed via the HW UART or the HW USB peripheral within the PIC. Once the bootloader is resident , you need to press a button to initiate the programming of the PIC with your program.
I'm not aware of any PICs that have a bootloader preinstalled.

Jay

eng.mohamedtoumi · Joined: 13 Jan 2018 Posts: 23 Location: Tun

okey thanks for your reply ...
So now i will burn i have to burn a bootloader to my 18F2550 ...
as i ve seen burning bootloader need a 4MHz external crystal ... while in my project i'm using the 8Mhz internal oscillator ... can i run the code (writen with 8Mhz internal oscillator) and burn it to a Mcu with 4Mhz external oscillator
??
Thanks

Ttelmah · Joined: 11 Mar 2010 Posts: 19545

No. You can use your crystal. You just have to code the bootloader to match your oscillator configuration.
However if you are using the internal oscillator you cannot use USB, so your bootloader will have to be serial not USB.
You doe reaslise the 18Fx550, needs a crystal that is a multiple of 4MHz, to do USB?.

temtronic · Posted: Wed May 16, 2018 11:55 am

Mr T's right , of course. What I do with 2550 /4550 projects is printout the 'clock diagram' fig 2-1 to decide how to design/code for clock. It's easy to see that you need a real or external xtal to use USB.
You can use your 8MHz xtal as there's a divider available to make 4MHz that then feeds the PLL for USB clock.

Jay

Ttelmah · Joined: 11 Mar 2010 Posts: 19545

He says: " i'm using the 8Mhz internal oscillator ".
Problem is this won't support USB. OK for serial, but pointless for a USB chip....