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-rw-r--r--firmware/doc/dfu.txt42
1 files changed, 42 insertions, 0 deletions
diff --git a/firmware/doc/dfu.txt b/firmware/doc/dfu.txt
index 9b40c3c..78fe5a6 100644
--- a/firmware/doc/dfu.txt
+++ b/firmware/doc/dfu.txt
@@ -86,4 +86,46 @@ dfu_api x x flash (const anyway)
dfu_state x x RAM
+preconditions:
+ - dfu code assumes to be loaded to address zero to make it work from both ram and rom
+
+startup:
+ - exception vectors (in flash)
+ - call lowlevel_init
+ - setup user/supervisor/FIQ/IRQ stack
+ - relocate dfu_state
+ - if DFU switch is pressed
+ - jump to dfu_main in flash
+ - relocate all of DFU .text/.data into ram (including exception vectors)
+ - initialize DFU .bss
+ - remap RAM to address zero
+
+ - if DFU switch is not pressed jump to entry address of app
+ - Cstartup_app.S
+ - relocate application .data
+ - initialize application .bss
+ - jump to appliction main
+ - application uses dfu_api in flash, pointing to in-flash data
+ - application calls dfu_switch()
+ - disable all interupts but USB
+ - relocate all of DFU .text/.data into ram (including exception vectors)
+ - remap RAM to address zero
+ - check whether app has already remapped RAM before !?!
+
+memory map:
+
+load_addr run_Addr
+0x00100000 0x00000000 exception vectors (DFU Cstartup)
+ Cstartup_SAM7
+
+ 0x00200000
+
+
+DFU constants:
+_etext:
+_data: 0x200000
+_edata:
+
+APP contants:
+_data: _edata_dfu
personal git repositories of Harald Welte. Your mileage may vary