US 11,705,904 B2
System and method for selecting an operating mode, such as a boot mode, of a micro-controller unit
Daniele Mangano, San Gregorio di Catania (IT); and Alessandro Inglese, San Pietro Clarenza (IT)
Assigned to STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed by STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on Feb. 15, 2022, as Appl. No. 17/671,844.
Claims priority of application No. 102021000003542 (IT), filed on Feb. 16, 2021.
Prior Publication US 2022/0263509 A1, Aug. 18, 2022
Int. Cl. H03K 19/0175 (2006.01); G06F 13/12 (2006.01)
CPC H03K 19/017581 (2013.01) [G06F 13/124 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A system, comprising:
a micro-controller unit (MCU) including an input pin operable as a general purpose input/output interface of the MCU, an internal pull-up circuit coupled to the input pin and an internal pull-down circuit coupled to the input pin;
an external pull-up circuit selectively coupled to the input pin;
an external pull-down circuit selectively coupled to the input pin;
wherein in a first configuration mode the external pull-up circuit and external pull-down circuit are decoupled from the input pin and the input pin is in a floating state;
a control logic operatively coupled to the MCU and programmed to:
configure the MCU according to one internal input mode between: an internal pull-up mode by coupling the internal pull-up circuit to the input pin to provide a first internal voltage logic value to the input pin, and an internal pull-down mode by coupling the internal pull-down circuit to the input pin to provide a second internal voltage logic value to the input pin;
acquire a first input voltage signal from the input pin having, during said first configuration mode, one of the first and second internal voltage logic values according to the internal input mode in which the MCU is configured;
further configure the MCU according to another internal input mode between the internal pull-up mode and the internal pull-down mode;
acquire a second input voltage signal from the input pin having, during said first configuration mode, another one of the first and second internal voltage logic values according to another internal input mode in which the MCU is further configured; and
select an operating mode of the MCU based on said first and second input voltage signals.