MSPM0L1304: Configuration of NRST and I2C SCL for bootloader

SY Yoon

Genius 3381 points

Part Number: MSPM0L1304

Hi,

I have a question about I2C bootloader.

NRST pin is muxed with PA1 for 16-pin SOT package.

PA1 is required to use the BSL for I2C.

NRST pin must be pulled up to VDD and TI recommends connecting an external 47-kΩ pullup resistor with a 10-nF pulldown capacitor.

But PA1 is connected pull-up resistor to VDD.

How should the NRST and SCL pins be configured to use I2C BSL for users who choose 16 pins?

Thanks.

0 Xiaodong LI over 2 years ago

Hi SY Yoon

PA18 is BSL Invoke.

if BSL Invoked, PA1 wil be set as I2C SCL

if there is no BSL Invoke, PA1 is NRST function.

Thanks!

0 SY Yoon over 2 years ago in reply to Xiaodong LI

Genius 3381 points

Hi Xiaodong LI,

NRST is muxed with I2C SCL.

I want to know pullup resistor value of PA1.

When PA1 is NRST function, it requires 47-kΩ pullup resistor with a 10-nF pulldown capacitor.

But when PA1 is set as I2C SCL, only requires pull up resistor.

Normally I2C pullup resistor is smaller than 47-kΩ.

And Is it okay if the capacitor is connected to the clock signal?

+1 Xiaodong LI over 2 years ago in reply to SY Yoon

Hi SY Yoon

Please keep 47-kΩ pullup resistor with a 10-nF pulldown capacitor on PA1 to garentee NRST function.

47-kΩ pullup resistor with a 10-nF pulldown capacitor should be OK for I2C communication on BSL if BSL is invoked.

on the real board, we can slightly adjust the capacitor value from 10nF to 1nF.

Thanks!

0 SY Yoon over 2 years ago in reply to Xiaodong LI

Genius 3381 points

Hi Xiaodong LI

Thank you for your kind reply.

And it is very helpful.

Thank you.

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