Rev. 1.00
60
September 11, 2018
Rev. 1.00
61
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
Watchdog Time-out Reset during Normal Operation
The Watchdog time-out Reset during normal operation is the same as the
RES reset except that the
Watchdog time-out flag TO will be set to "1".
WDT Time-out
Internal Reset
t
RSTD
+ t
SST
WDT Time-out Reset during Normal Operation Timing Chart
Watchdog Time-out Reset during SLEEP or IDLE Mode
The Watchdog time-out Reset during SLEEP or IDLE Mode is a little different from other kinds
of reset. Most of the conditions remain unchanged except that the Program Counter and the Stack
Pointer will be cleared to "0" and the TO flag will be set to "1". Refer to the A.C. Characteristics for
t
SST
details.
WDT Time-out
Internal Reset
t
SST
WDT Time-out Reset during SLEEP or IDLE Timing Chart
Reset Initial Conditions
The different types of reset described affect the reset flags in different ways. These flags, known
as PDF and TO are located in the status register and are controlled by various microcontroller
operations, such as the SLEEP or IDLE Mode function or Watchdog Timer. The reset flags are
shown in the table:
TO
Reset Conditions
0
0
Power-on reset
u
u
RES or LVR reset during Normal or SLOW Mode operation
1
u
WDT time-out reset during Normal or SLOW Mode operation
1
1
WDT time-out reset during IDLE or SLEEP Mode operation
Note: "u" stands for unchanged
The following table indicates the way in which the various components of the microcontroller are
affected after a power-on reset occurs.
Item
Condition after Reset
Program Counter
Reset to zero
Interrupts
All interrupts will be disabled
WDT,Time Base
Clear after reset, WDT begins counting
Timer Modules
Timer Modules will be turned off
Input/Output Ports
I/O ports will be setup as inputs
Stack Pointer
Stack Pointer will point to the top of the stack
The different kinds of resets all affect the internal registers of the microcontroller in different ways.
To ensure reliable continuation of normal program execution after a reset occurs, it is important to
know what condition the microcontroller is in after a particular reset occurs. The following table
describes how each type of reset affects each of the microcontroller internal registers.