The BQ25155 device may be configured to perform a system hardware reset (Power Cycle/Autowake), go into Ship Mode, or simply do nothing after a long button press (for example, when the MR pin is driven low until the MR_HW_RESET timer expires).The action taken by the device when the timer expires is configured through the MR_LPRESS_ACTION bits in the ICCTRL1 Register section. Once the MR_HW_RESET timer expires the device immediately performs the operation set by the MR_LPRESS_ACTION bits. The BQ25155 sends an interrupt to the host when the device detects that MR has been pressed for a period that is within t_{RESET_WARN} from reaching t_{HW_RESET}. This may warn the host that the button has been pressed for a period close to t_{HW_RESET} which would trigger a HW Reset or used as another button press timer interrupt like the WAKE1 and WAKE2 timers. This interrupt is sent before the MR_HW_RESET timer expires and sets the MRRESET_WARN flag. The t_{RESET_WARN} may be set through I²C by the MR_RESET_WARN bits in the MRCTRL register. The host may change the reset behavior at any time after MR going low and prior to the MR_HW_RESET timer expiring. It may not change it however from another behavior to a HW reset (Power Cycle/Autowake) since a HW reset can be gated by other condition requirements, such as valid VIN presence (controlled by MR_RESET_VIN bit), throughout the whole duration of the button press. This flexibility allows the host to abort any reset or power shutdown to the system by overriding a long button press command.

A HW reset may also be started by setting the HW_RESET bit. Note that during a HW reset , VDD remains on.

Figure 9-5 MR Wake and Reset Timing with VIN Present or BAT Active Mode When MR_LPRESS_ACTION = 00

Figure 9-6 MR Wake and Reset Timing Active Mode When MR_LPRESS_ACTION = 1x (Ship Mode) and Only BAT is Present