18F2620 compile problems in PBP

[Charles Linquis]

If it works like the 8722, when you load the bootloader in the chip, you can set the config fuses so that the PLL is enabled. The 1Mhz default will be multiplied by 4, giving you the 4Mhz you want.

[Bruce]

The MCS boot-loader firmware has config fuse options already set. You cannot over-ride these when loading your code into the target using the boot-loader software.

I.E. whatever the config fuse settings are in the loader firmware you're stuck with.

The only way to change config fuse settings, when using the MCS boot-loader, is to re-program the PIC with a different boot-loader firmware file.

Whatever config fuse settings you may have embedded in your .hex file at compile time are simply ignored when you load your code using the boot-loader software. The boot-loading process does not alter config fuse settings.

Note: The MCS boot-loader works only with an external oscillator. If you change this in the loader firmware before programming, it probably isn't going to work. At least not reliably.

[Joe Rocci]

......Note: The MCS boot-loader works only with an external oscillator. If you change this in the loader firmware before programming, it probably isn't going to work. At least not reliably.

----------------

Bruce,

Why so? Why can't I write a loader that uses the internal clock? It certainly can't be an accuracy/stability issue - I have thousands of units in the field for a couple of years running serial comms with the internal clock over very wide temperature ranges. That much works fine.

And if I CAN write a loader that uses the internal clock, then why can't I modify the MCS loader to do the same by disassembling, modifying, and reassembling?

Thanks

Joe

[Bruce]

Hi Joe,

You can modify the MCS loader files if you like. They just won't work as-is
with the internal oscillator.

[Charles Linquis]

I over-rode the bootloader config settings.

I use the Microchip ICD2 to program the bootloader into the device. If you first load the proper bootloader file, you can then change the configuration fuse settings in the ICD2 "config" section. Program the part, and away you go.

I have programmed several 18F8722s that had no external oscillator whatsoever. I simply set the "PLL ENABLED" and "Internal OSC" options in MPLAB and programmed it with the 4Mhz bootloader. MCLoader had no trouble at all loading my program files.

[Joe Rocci]

Thanks for the helpful suggestion Charles. It's always great to hear waht CAN be done instead of what CAN't be done

Joe