PIC Bootloader

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HerbertMunch

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Ive been looking around the internet at bootloading.

This may be a stupid question, but, why does everyone seem to use a hardware switch to enter bootloader mode?

Cant i just do the following?
Using the microchip generic framework as a starting point,
Write my own bootloader code,
assign a 'Command' to bootloader mode.
Send the command from the pc and just enter bootloader mode.

Is this possible, or am i overlooking something?

Many thanks
 
You can do that... You can use almost any trigger mechanism you like...

I prefer the hardware trigger and I often use an existing switch in the project and simply test to see if the switch is pressed during power up... This way I don't have to dedicate a pin for the bootloader trigger...
 
Last edited:
HerbertMunch said:
This may be a stupid question, but, why does everyone seem to use a hardware switch to enter bootloader mode?
Click to expand...

They don't, I've never used a bootloader that does - they simply check for a serial input for a fixed time, if they don't find one they boot the existing code. I've always thought a bootloader requiring a switch was a waste of time.
 
Nigel Goodwin said:
They don't, I've never used a bootloader that does - they simply check for a serial input for a fixed time, if they don't find one they boot the existing code.
Click to expand...
Perhaps not for serial bootloader, but most of the USb ones ive come across do, including the Microchip offering.

Nigel Goodwin said:
I've always thought a bootloader requiring a switch was a waste of time.
Click to expand...
I agree.
 
blueroomelectronics said:
Take a look at the tiny PIC bootloader. It waits a second after boot for a bootloader request.
Click to expand...


Thanks bill, but I require a USB implementation. Looks like ill have to code it myself to get exactly what I want.
 
HerbertMunch said:
Perhaps not for serial bootloader, but most of the USb ones ive come across do, including the Microchip offering.
Click to expand...

There may well be a sound reason for it with USB?, it's a VERY different beast to serial.
 
I use an adaptation of the Microchip bootloader with the 18F1320. I have a couple of products where I'd like to be able to update the firmware from time to time and I just check the state of the RX serial port on startup. If it is high then there is a MAX232 serial interface connected to it and it goes into bootloader mode. If its low then it jumps to the main code.
 
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