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pic18f4550 bootloader is not working, Can I reprogram it using ISP or something?

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Junior Member level 2
Mar 6, 2011
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Hi all,

I am all new to microcontrollers. I have a dev kit with pic18f4550, The pic came with a boot loader which was invoked or started by pressing the buttons given on the board. The problem - It was given in the documentation that the pic mcu must have hs+pll, hs usb configuration for crystal / oscilator to work. So I have changed the oscillator config bits in the mplab and eported the hex file and programmed it using a USB wire connected to pc.

Bootloader was supposed to reprogram the chip using USB wire, Now the bootloader is not working and I am also not able to write to the pic using the usb wire since bootloader is not working.

Is it that the chip is damaged because I used a wrong conf bit for the osscilator or is it that the bootloader is erased and so I need an external hardware such as ISP to reprogram the chip with a bootloader hex and continue using the bootloader laterz?

Please do reply me.

Thanks a lot

The difference between wrong fuses and erased bootloader doesn't matter much. In both cases, you'll need to reprogram it with an ISP adapter.

You'll need of course a bootloader hex file. I my opinion, a good bootloader should be protected against accidental overwrite, by the way.

its rare for a PIC to get damaged
you can use the JDM programmer with picpgm software to reprogram the PIC18F2550
you can get the picpgm software from here
**broken link removed**

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