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<section begin="History" />{| style="border-collapse:collapse; "! colspan="4" style="width:100%; text-align:left" ; border-bottom:solid 2px #ededed" |History|- ! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Issue Date! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#73B2C7; padding:5px; color:white" |Notes|-| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |{{InfoBoxTopoldid|5204|2016/07/21}}| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |New documentation layout|-| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |{{AppliesToAXELULiteoldid|7028|2017/08/04}}{{InfoBoxBottom}| style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#edf8fb; padding:5px; color:#000000" |Add PMIC_PWRON information|-! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#ededed; padding:5px; color:#000000" |2020/10/15! style="border-left:solid 2px #73B2C7; border-right:solid 2px #73B2C7;border-top:solid 2px #73B2C7; border-bottom:solid 2px #73B2C7; background-color:#ededed; padding:5px; color:#000000" |Minor changes|}<section end="History" />__FORCETOC__<section begin="Body" />
== Reset scheme and control signals ==
Reset scheme is strictly related to power supply unit. As such, reading of [[Power (AXEL ULite)|this page]] is strongly recommended.
The following picture shows the simplified block diagram of reset scheme and voltage monitoring.
Some signals that are related to reset circuitry are pulled-up to VDD_SNVS_IN. This voltage is generated by PMIC PF3000's VSNVS LDO/Switch and its actual value depends on:
* voltage applied to PF3000 VIN pin
** in case of AXELULite AXEL ULite this pin is connected to VIN_SOM power rail
* voltage applied to PF3000 LICELL pin
** in case of AXELULite AXEL ULite this pin is connected to pin 14 of SODIMM connector (PMIC_LICELL).
Hence '''it is recommended that system designer takes into account these factors in order to properly manage these signals at carrier board level'''.
=== Handling CPU-initiated software reset ===
By default, iMX6UL processor does not assert any external signal when it initiates a software reset sequence. This might not guarantee a safe system reset in all conditions. For these reasons, AXELULite AXEL ULite integrates a specific circuit that, in combination with the use on iMX6UL watchdog timer (WDT), guarantees a full hardware reset in case a software reset is issued. It is worth remembering that when this reset is triggered, a full power up cycle is issued. This technique makes use of the GPIO1_IO08 pin. Particular attention needs to be paid in case this pin needs to be used at carrier board level as well. For more details please contact the [mailto:support-axel@dave.eu technical support].
This technique is supported by [[AXELULite_and_SBC_Lynx_Embedded_Linux_Kit_AXEL ULite and SBC Lynx Embedded Linux Kit (XUELK)|AXELULite AXEL ULite Embedded LinuxKit]].
==== Forcing a software reset using an external signal ==== As described before, GPIO1_IO08 is used by internal watchdog for triggering a software reset using [[Pinout_(AXEL_ULite)#PMIC_PWRON|PMIC_PWRON]]. The same input signal, can be used with an external push-button for triggering a software reset too. [[Pinout_(AXEL_ULite)#PMIC_PWRON|PMIC_PWRON]] has an internal pull-up (see [[Reset_scheme_(AXEL_ULite)#Reset_scheme_and_control_signals|Reset scheme]]) and must be driven with an open-drain signal ===References===
{{reflist}}
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