MSP430: BSL mode - UART transmit pin

Hello:

In several MCUs of the MSP430 family, during the bootstrap loader mode,
the normal UART Tx/Rx transmit/pins aren't used. Instead, other pins are 
alloted for BSL transmit and receive.

Would you know if the normal Tx transmit output pin goes in 
high-impedance mode during the BSL mode?

Also, is there any register bit or pin offering information on
"normal" vs "BSL" status?

Thanks.

Jerry

On Apr 29, 3:56 pm, JerryS <NOM...@videotron.ca> wrote:

> Also, is there any register bit or pin offering information on
> "normal" vs "BSL" status?

I've never seen an app note that discusses it. However, my
understanding of BSL  mode is that it is implemented as an actual
MSP430 program resident in mask-ROM on the chip. This implies that
unless the program specifically initializes unused pins, all I/O
drivers will be in the POR state, which in almost all cases is hi-Z.

You should check this on a device specific basis with your TI FAE. But
I would bet money on it.

larwe wrote:
>>Also, is there any register bit or pin offering information on
>>"normal" vs "BSL" status?
> 
> 
> I've never seen an app note that discusses it. However, my
> understanding of BSL  mode is that it is implemented as an actual
> MSP430 program resident in mask-ROM on the chip. This implies that
> unless the program specifically initializes unused pins, all I/O
> drivers will be in the POR state, which in almost all cases is hi-Z.
> 
> You should check this on a device specific basis with your TI FAE. But
> I would bet money on it.

Thank you for your posting.

This is what TI replied to our HW designer (who's using the two diodes 
amd a pull-up resistor to connect the two Tx outputs together, the 
normal one and the BSL one):

TI:
------
Your assumptions about the UTXDO and URXDO in BSL mode are correct.
------

HW designer:
-------
My issue is resolved based on the assumptions that in BSL mode, always:

UTXDO is OUT in High state [he means High level, not
high-impedance, here]

URXDO is IN

Should I consider these reliable assumptions?
--------

Jerry