STM32L476RET JTAG TAP Chain failed when unsued pin connect as analog ?

[SCorb.1]

Hi,

I work on custom board with STM32 chained with SAMAD2 processor on JTAG.

Architecture is that below :

JTAG_TDI -> SAMA5D2 TDI -> SAMA5D2 TDO -> STM32 TDI (PA15) -> STM32 TDO (PB3) -> JTAG TDO

This work fine when STM32 is empty (no code) or when I disable free pin as analog for reduce power consumption. But when I try to enable free pin as analog JTAG chain not working.

I'don't find a particular reason on reading quickly datasheet. Is there any reason to have behaviour.

Find in attachement screen shot of pinout assignement.

Regards,

Sébastien Corbeau

[Uwe Bonnes]

Nearly all STM32 have the errata:

2.1.14 Full JTAG configuration without NJTRST pin cannot be used . . . . . . . . 18

So if you change PB4, JTAG will fail.

I wonder why this has never been fixed.

[SCorb.1]

Thanks for answer.

That's explain maybe my problem even if it's talk about debug mode no JTAG TAP.