Infrared light emitting diode control circuit

• US 10,470,275 B2
• Filed: 05/21/2018
• Issued: 11/05/2019
• Est. Priority Date: 12/16/2015
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Sarangdhar, Nitin V., Moore, Victoria C., Dwarakanath, Kumar Narasimhan
• Primary Examiner(s): A, Minh D
• Assistant Examiner(s): Cho, James H
• Application Number:
  US15/984,624
• Publication Number:
  US 20180279449A1
• Time in Patent Office: 533 Days
• Field of Search: None
• CPC Class Codes: G06F 21/32 using biometric data, e.g. fingerprints, iris scans or voiceprints
• CPC Class Codes: G06F 21/82 Protecting input, output or interconnection devices
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold
• CPC Class Codes: G08B 5/36 using visible light sources
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: H05B 47/115 by determining the presence or movement of objects or living beings
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

Disclosed in some examples are devices, methods, and machine-readable mediums for reliable control of IR LEDs. In some examples, a microcontroller running firmware controls whether the LED is activated or not by use of a disable signal. The microcontroller enables or disables the operation of the LED based upon a user'"'"'s proximity to the LED, a watchdog timer, and a confirmation that only trusted software is executing.

Claims

1. A microcontroller for controlling a light emitting diode (LED), the microcontroller comprising:

a firmware to configure the microcontroller to perform operations of;

determining that a deactivation condition from a set of one or more deactivation conditions is present, the set of one or more deactivation conditions comprising;

a software attestation deactivation condition that is met when software executing on a central processing unit coupled to the microcontroller fails an attestation; and

responsive to determining that the deactivation condition has been met, preventing activation of the LED.

2. The microcontroller of claim 1, wherein the set of one or more deactivation conditions further comprise:

a proximity deactivation condition that is met by receiving an indication from a proximity sensor of a presence of an object within a predetermined distance from the LED.

3. The microcontroller of claim 1, wherein the set of one or more deactivation conditions further comprise:

a timer deactivation condition that is met by determining that an unexpired watchdog timer is running, the operations comprising starting the watchdog timer when the LED is turned off.

4. The microcontroller of claim 3, wherein the watchdog timer is implemented by the firmware.

5. The microcontroller of claim 1, wherein the firmware is configured to continuously monitor the set of one or more deactivation conditions and in response to detecting that none of the set of one or more deactivation conditions are present, allowing activation of the LED.

6. The microcontroller of claim 1, wherein the firmware is configured to prevent activation of the LED by sending a disable signal to a power management integrated circuit (PMIC), the PMIC refraining from sending an activation signal to activate the LED responsive to receiving the disable signal from the microcontroller.

7. The microcontroller of claim 1, wherein the firmware is configured to prevent activation of the LED by refraining from sending an activation signal to the LED in response to receiving an enabling signal from the central processing unit coupled to the microcontroller.

8. A method comprising:

using a processor;

determining that a deactivation condition from a set of one or more deactivation conditions is present, the set of one or more deactivation conditions comprising;

a software attestation deactivation condition that is met when software executing on a central processing unit coupled to the processor fails an attestation; and

responsive to determining that the deactivation condition has been met, preventing activation of an LED.

9. The method of claim 8, wherein the set of one or more deactivation conditions further comprise:

a proximity deactivation condition that is met by receiving an indication from a proximity sensor of a presence of an object within a predetermined distance from the LED.

10. The method of claim 8, wherein the set of one or more deactivation conditions further comprise:

a timer deactivation condition that is met by determining that an unexpired watchdog timer is running, the watchdog timer configured to start when the LED is turned off.

11. The method of claim 10, wherein the watchdog timer is implemented by the processor.

12. The method of claim 8, comprising continuously monitoring the set of one or more deactivation conditions and in response to detecting that none of the set of set of one or more deactivation conditions are present, allowing activation of the LED.

13. The method of claim 8, comprising preventing activation of the LED by sending a disable signal to a power management integrated circuit (PMIC), the PMIC refraining from sending an activation signal to activate the LED responsive to receiving the disable signal from the processor.

14. The method of claim 8, comprising preventing activation of the LED by refraining from sending an activation signal to the LED in response to receiving an enabling signal from the central processing unit coupled to the processor.

15. A non-transitory machine readable medium that stores instructions which when performed by a machine, cause the machine to perform operations comprising:

determining that a deactivation condition from a set of one or more deactivation conditions is present, the set of one or more deactivation conditions comprising;

a software attestation deactivation condition that is met when software executing on a central processing unit coupled to the microcontroller fails an attestation; and

responsive to determining that the deactivation condition has been met, preventing activation of an LED.

16. The non-transitory machine readable medium of claim 15, wherein the deactivation conditions further comprise:

a proximity deactivation condition that is met by receiving an indication from a proximity sensor of a presence of an object within a predetermined distance from the LED.

17. The non-transitory machine readable medium of claim 15, wherein the deactivation conditions further comprise:

a timer deactivation condition that is met by determining that an unexpired watchdog timer is running, the watchdog timer started when the LED is turned off.