MSPM0L1305: Boot Loader Query

Preetham Y

Prodigy 40 points

Part Number: MSPM0L1305

Hi,

I am using the MSPM0L1305 (16‑pin WQFN package) in my design.

For initial programming, I am using the I²C ROM Bootloader (BSL_I2C).

In my hardware:

I²C pins (SCL/SDA) are routed for BSL usage
NRST is multiplexed with SCL0, so I cannot use NRST as a dedicated external reset
The BSL_INVOKE pin is used for another purpose and is not available
For blank MCUs, I²C BSL works automatically, which is fine

My question is:

After I load firmware into the MSPM0L1305, can I still invoke the I²C bootloader purely through software (runtime BSL invoke), without using NRST or the BSL_INVOKE pin?

Since I'm using SCL0 and NRST on the same pin, will there be any issue while debugging and during boot loading? Should I change something?

Precisely, I'm using the 5th pin of MSPM0L1305SRTRR as BSL_SCL initially to load the firmware.. Then later it will be used as I2C_SCL0 to send commands if needed.. Meanwhile can it act as NRST ?

6 days ago

0 Owen Li 3 days ago

TI__Expert 6321 points

Hi Preetham,

You can invoke the bootloader purely through software without needing to use an external pin.

Please refer to the MSPM0 Bootloader User's Guide and MSPM0 Bootloader Implementation.

Best,

Owen

0 Preetham Y 3 days ago in reply to Owen Li

Prodigy 40 points

Hi Owen,

Thanks for the reply

I have one doubt regarding SWD.
Does the SWD interface require the NRST pin?
In my design, I am using SWDIO and SWCLK strictly for SWD, and I will not reassign or modify them in firmware.
From the documentation, I understand that NRST is only required if the SWDIO and SWCLK pins are repurposed or disabled in software. Otherwise, SWD can operate normally without needing NRST.

0 Owen Li 3 days ago in reply to Preetham Y

TI__Expert 6321 points

Hi Preetham,

The SWD interface does not require the NRST pin, however if it is not pulled high, the device won't start.

Best,

Owen

0 Preetham Y 3 days ago in reply to Owen Li

Prodigy 40 points

Hi Owen,

Thanks for the clarification. Since this pin will later be used as SCL0, we have already added a pull‑up resistor on the line. My question is: even after the NRST/SCL0 pin is configured as SCL0 by the firmware, will the SWD interface (SWDIO/SWCLK) still function normally without the need for NRST?

Regards
Preetham

0 Owen Li 3 days ago in reply to Preetham Y

TI__Expert 6321 points

Hi Preetham,

The SWD interface does not require the NRST pin.

Best,

Owen

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MSPM0L1305: Boot Loader Query