L073 strange behaviour after 2nd bootloader jump to app

[LCE]

Heyho,

playing with the L073, partitioned the flash for bootloader "BL" (bank 1) and application (bank 2).

No writing of app yet, just testing jumping back and forth.

I just added a no-init variable for communication between BL and app, mainly to tell the BL to not jump back to app if the app requested so.

• at power up / reset, the uninitialized variable "u32AppRqstBootloader" is 0, so the BL jumps to the app, and just for checking: before the jump the BL sets u32AppRqstBootloader = 0xB0072ABB
• in the app u32AppRqstBootloader is printed via UART, and it shows the expected 0xB0072ABB, the printf is done immediately and takes ~ 2 ticks (1 tick = 1 ms)
• now I let the app jump to BL, before the jump the app sets u32AppRqstBootloader = 0xABB1B007 so the BL does not jump

So far so good...

But when the BL now jumps back to the app, all of a sudden in the app there's a ~ 1 second delay before u32AppRqstBootloader is printed - everything else is working fine - or so I think... (the next printf requested via UART user interface of that variable is quick again).

If it jumps more often back and forth, it behaves the same: BL prints quickly, the app has the 1 s delay.

I don't find that the application is doing anything differently than after the 1st jump.

I cannot debug this via ST-Link / SWD, it seems the debugger has problems with the jumping between the projects.

Any ideas?

 

PS: here's a copy of the terminal

// 1st start:

**************
* BOOTLOADER *
...

Tick 37
u32AppRqstBootloader 00000000
Tick 39

jump to APP...

џ

// jump okay, now we're in...
 
***************
* APPLICATION *
...

Tick 37
u32AppRqstBootloader B0072ABB
Tick 40 // <<< quick printf after 1st start / jump

// user input via terminal:
> cw Sboot

jump to BL...

џ

// we're back in...
**************
* BOOTLOADER *
...

Tick 37
u32AppRqstBootloader ABB1B007
Tick 39

// user input to jump back to app
> cw Sjapp

jump to APP...

// and we're back in app:
***************
* APPLICATION *
...

Tick 37

// ###### and HERE is the delay, see tick below #######

u32AppRqstBootloader B0072ABB
Tick 1040

 

[LCE]

It seems I make the mistake far before the printf... checking stuff between the tick outputs...

Still strange that this only happens after 1st start.

[LCE]

Almost got it:

the app's ADC's internal calibration times out.

But why? Let's find out...

The bootloader does not use the ADC, so it has something to do with the ADC de-init when leaving the app.

[LCE]

"Again what learned" as they say in Germany...

I just took the big hammer and disabled the ADC by setting CR = 0 and disabling the peripheral clock.

Now I found out there's this ADDIS bit to be set and wait for ADEN = 0.

And lo and behold, no more delay!