Ship mode and Break-to-wake mode are the lowest power consumption modes. Ship mode provides the lowest current consumption IQSHIP.

Ship mode

There are two ways to enter and wake up from Ship mode.

The button connected to the SHPHLD pin is one way to access Ship mode, as described by the following.
  • Press the button for a duration of tPWROFF. The chip enters Ship mode when the button is released (SHPHLD returns high).
  • To wake up the device, press the button again. The debounce time is tSHPHLD_DEB_SHP.
The second way to enter and wake up from Ship mode is through a task register. In addition, either SHPHLD edge can be used for wakeup by doing the following:
  • TWI configures the desired edge for wakeup in WAKEUP and checks that the SHPHLD pin is in an inactive state (HIGH when the falling edge is selected, and LOW when it is a rising edge). Pin state is visible in register MAIN.STATUS. TWI then activates the task in register TASKS_SHIP to enter Ship mode.
  • Wakeup happens when a suitable edge appears on the SHPHLD pin. The debounce time is tSHPHLD_DEB_SHP.

The SHPHLD pin includes both pull-up and pull-down resistors which can be controlled through register SHPHLD. Pull-up (default) is used together with a button. Pull-down can be used in Active mode to avoid a floating input pin.

Note: When rising edge detection has been selected, the external voltage on the SHPHLD pin must remain below VBAT to avoid leakage current towards the battery. If voltage is higher, an external series resistor or resistor divider can help to reduce the leakage.

Break-to-wake mode

Break-to-wake mode is a variant of Ship mode where wakeup happens once a connection between the SHPHLD pin and ground is broken. It is the second lowest current consumption (IQBREAKTOWAKE) mode of the device.

The SHPHLD pin is connected to ground using a wire or similar, and the system is set to break-to-wake mode for storage and transport. Once the wire is broken during first use, the system wakes up.

To configure Break-to-wake mode the pull-up resistor needs to be disabled and a suitable pull-up current PUCURR activated in register SHPHLD. The recommended setting is Low. If additional leakage is present on the PCB trace connected to SHPHLD, setting Moderate or High can be used. Rising edge wakeup is set in register WAKEUP. Break-to-wake mode is then entered using task TASKS_SHIP. In addition, software has to make sure that the SHPHLD pin is LOW before activating the task.