topic KLO3 VLPS mode hindered by light-sensitive LED (?) in Kinetis Microcontrollers https://community.nxp.com/t5/Kinetis-Microcontrollers/KLO3-VLPS-mode-hindered-by-light-sensitive-LED/m-p/461770#M27685 <HTML><HEAD></HEAD><BODY><P>I was having trouble with consistently entering VLPS mode (Very-Low-Power Shutdown mode) with a FRDM-KL03Z development board.&nbsp;&nbsp; It appears that light shining on the LED hinders the KL03 MCU from entering VLPS mode.&nbsp; Once in VLPS mode, the addition of light does not appear to affect VLPS mode.&nbsp;&nbsp; Apparently the photovoltaic properties of the LED are feeding a small amount of voltage to the MCU, and somehow corrupting entry into VLPS mode.&nbsp; I'm wondering if anyone has an explanation for this, or has had a similar problem.&nbsp; My final product won't have LED's, so it's not a huge concern for me presently, but it could really mess up some products.&nbsp; Putting tape over the LED solved the problem, as did also configuring the pins connected to the LED as ALT0 inputs.&nbsp; Any comments would be appreciated.</P><P></P><P>A clarification:&nbsp; The LED I am referring to on the FRDM-KL03Z board is the tri-color red/green/blue LED.&nbsp; I had previously reconnected the red &amp; green parts of the RGB LED to PTB3 &amp; PTB4 (with open drain outputs) to make the normal outputs available for other use; that may be a factor.&nbsp; </P></BODY></HTML> Wed, 11 May 2016 17:26:32 GMT thomasedel 2016-05-11T17:26:32Z KLO3 VLPS mode hindered by light-sensitive LED (?) https://community.nxp.com/t5/Kinetis-Microcontrollers/KLO3-VLPS-mode-hindered-by-light-sensitive-LED/m-p/461770#M27685 <HTML><HEAD></HEAD><BODY><P>I was having trouble with consistently entering VLPS mode (Very-Low-Power Shutdown mode) with a FRDM-KL03Z development board.&nbsp;&nbsp; It appears that light shining on the LED hinders the KL03 MCU from entering VLPS mode.&nbsp; Once in VLPS mode, the addition of light does not appear to affect VLPS mode.&nbsp;&nbsp; Apparently the photovoltaic properties of the LED are feeding a small amount of voltage to the MCU, and somehow corrupting entry into VLPS mode.&nbsp; I'm wondering if anyone has an explanation for this, or has had a similar problem.&nbsp; My final product won't have LED's, so it's not a huge concern for me presently, but it could really mess up some products.&nbsp; Putting tape over the LED solved the problem, as did also configuring the pins connected to the LED as ALT0 inputs.&nbsp; Any comments would be appreciated.</P><P></P><P>A clarification:&nbsp; The LED I am referring to on the FRDM-KL03Z board is the tri-color red/green/blue LED.&nbsp; I had previously reconnected the red &amp; green parts of the RGB LED to PTB3 &amp; PTB4 (with open drain outputs) to make the normal outputs available for other use; that may be a factor.&nbsp; </P></BODY></HTML> Wed, 11 May 2016 17:26:32 GMT https://community.nxp.com/t5/Kinetis-Microcontrollers/KLO3-VLPS-mode-hindered-by-light-sensitive-LED/m-p/461770#M27685 thomasedel 2016-05-11T17:26:32Z