Implementing a bootloader for nRF24LE1

[Daniel Huber]

Hi all,

I'm trying to implement two hex files into my processor, one application and one bootloader. In nRFgo Studio I enabled 2048 bytes in the NUPP field to get a protected and a unprotected area in flash. My bootloader will be placed at 0x3800 in flash with the -Wl-bHOME=0x3800 linker option and my application with the same option on 0x0000. The idea is, that with the NV data I can set the STP in FSR register to change the BootstartSelector. So that I can decide which program will be executed.

My question now is, do I implement two interrupt vector tables, one on either code location or do I only use one that I modify manually? i know that with above linker setting for the bootloader i leave the IVT on address 0x0000, but as soon as i program the application that gets overwritten.

I tried to work with two IVT's and as long as I only jump into the application at 0x0000 it works, but when I change the BootstartSelector upon programming it doesnt work anymore. Does that mean that the IVT has to be at address 0x0000? does the IVT execute absolute jumps?

Setup:

-processor: nRF24LE1 -compiler: SDCC version 3.3.1 -editor: eclipse

Thanks a lot in advance and sorry for my beginner questions!!!!

Daniel

[Håkon Alseth]

Hi Daniel,

First off; this is not a beginner question. ;-)

In 8051 the interrupt vectors start from 0x0000. When running code in a protected area (NUPP area), the code will be rebased to run from address 0x0000, while it is actually running from 0x3800 in your case. This means that you have no way of running a interrupt driven bootloader in NUPP area. You'll have to make a polling-based bootloader instead.

Note: NUPP protects you from eating up your own tail (bootloader overwriting itself or application erasing the bootloader), but it will not protect you from outside sources.

Best regards Håkon