ARM Technical Support Knowledge Articles

How do I switch ON/OFF my Versatile Express Motherboard V2M-P1?

Applies to: V2M-P1

Scenario

In previous ARM Development Boards belonging to the Versatile Family, there was a unique button to power the board ON and OFF with a simple and brief "press" action. The new family of boards "Versatile Express" has introduced a slight change to power the system ON and OFF. In this Knowledge Article we explain the procedure required to power the Versatile Express system ON and OFF.

The Versatile Express Motherboard V2M-P1 is fitted within a plastic enclosure and the user switches, push buttons, some connectors and ports are accessed from the rear panel of this enclosure. There are two power-related push buttons located on the rear panel of the board. The names used for these buttons in the Versatile Motherboard Express TRM slightly differ with the name printed on the PCB which causes some confusion that will be clarified in this Knowledge Article. There is no "silk screen" text on the rear panel; in other words the buttons are not marked. You can remove the upper lid of the enclosure to see the names written on the PCB, but in any case, the buttons are color-coded red and black for identification.

Answer

The Versatile Express system has two power states - ON and Standby. In the ON state, the entire system is powered up and the main ARM CPU runs your application code. In the Standby state, the main CPU does not run, but system is still partially powered and the various system configuration microcontrollers can talk to each other, and to the user via UART0. In order to completely power the system OFF, the external 12V power supply must be disconnected. When the board is first connected to the 12V supply, it enters Standby state, waiting for user input - whether that be via UART0, or by one of the push buttons.

Red button: This button is known as Power/Reset in the Motherboard Express TRM. The name printed on the back panel PCB (HBI-0197C) is ON/OFF. The functionality is as follows:

Black button: This pushbutton is known as Standby in the motherboard TRM. The name printed on the PCB is Reset.

Essentially, both buttons can be used to put the system in to Standby mode as described above, but only the red button can be used to power the system ON.

Aside from the red push button switch on the back panel, there are three other methods of switching the board ON -

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