TTP255 datasheet(18/49 Pages) TONTEK

18 / 49 page

Preliminary

TTP255

TonTouch

12’/08/21

Page 18 of 49

Ver3.0

.External Reset (RSTB)

This is one kind of system resetting signal, but only forced externally.

When the chip acknowledged the low level from the pin RSTB exceed 1 us,

it will generate the reset procedure to reset CPU & all the peripheral back

to their initial state (default values).

.Burn out Reset (Program sequence abnormal)

As CPU out of program area, the CPU can detect the abnormal

condition and generate a system reset request.

.Watch Dog Timer Reset

The reset signal will generate automatically when the watchdog timer

runs overflow. If the watchdog timer is cleared regularly by users’ program,

no watchdog reset will occur. Unless the MCU is forced into abnormal state,

the software controlled procedure is disrupted and causing watch dog

timer overflow, then it will generate reset signal to initializes the chip

returning to normal operation.

.Low Voltage Reset (LVR)

The LVR function is used to monitor the supply voltage of MCU, it will

generate a reset signal (with 4*OSCL de-bounce time but no de-bounce in

stop mode) to reset the microcontroller as the VDD power falls below the

default setting level VLVR. It can also be enabled or disabled by

programming “LVREN” bit in PS register.

RESETF: reset source flag register[R/W], power on value [0000]

Bit3

Bit2

Bit1

Bit0

Bit Name

ROMF

BOF

LVRF

WDTF

Read/Write

R/W

WDTF: Watch dog timer overflow reset flag (0: no active; 1: active)

LVRF: Low voltage reset flag (0: no active; 1: active)

BOF: Burn out flag(0: no active; 1: active)

ROMF: ROM fail flag(0: no active; 1: active)

(The RESETF is cleared by system reset only)

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