Rev. 1.71
50
April 11, 2017
Rev. 1.71
51
April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
More information regarding external reset circuits is located in Application Note HA0075E on the
Holtek website.
Pulling the RES Pin low using external hardware will also execute a device reset. In this case, as in the
case of other resets, the Program Counter will reset to zero and program execution initiated from this point.
Note: t
RSTD
is power-on delay, typical time=16.7ms
RES Reset Timing Chart
•
RSTC External Reset Register – HT66F002/HT66F003
Bit
7
6
5
4
3
2
1
0
Name
RSTC7
RSTC6
RSTC5
RSTC4
RSTC3
RSTC2
RSTC1
RSTC0
R/W
R/W
R/W
R/W
R/W
R
R
R/W
R/W
POR
0
1
0
1
0
1
0
1
Bit 7 ~ 0
RSTC7 ~ RSTC0
: PA7
/
RES selection
01010101: configured as PA7 pin or other function
10101010: configured as RES pin
Other Values: Inhibit to use
All reset will reset this register as POR value except WDT time out Hardware warm reset.
•
RSTC External Reset Register – HT66F004
Bit
7
6
5
4
3
2
1
0
Name
RSTC7
RSTC6
RSTC5
RSTC4
RSTC3
RSTC2
RSTC1
RSTC0
R/W
R/W
R/W
R/W
R/W
R
R
R/W
R/W
POR
0
1
0
1
0
1
0
1
Bit 7 ~ 0
RSTC7 ~ RSTC0
: PC2/RES selection
01010101: Configured as PC2 pin or other function
10101010: Configured as RES
pin
Other Values: Inhibit to use
All reset will reset this register as POR value except WDT time out Hardware warm reset.
Low Voltage Reset – LVR
The microcontroller contains a low voltage reset circuit in order to monitor the supply voltage of
the device and provide
an
MCU reset should the value fall below
a
certain predefined level. The
LVR function is always enabled during the normal and slow modes with a specific LVR voltage
V
LVR
. If the supply voltage of the device drops to within a range of 0.9V~V
LVR
such as might occur
when changing the battery, the LVR will automatically reset the device internally and the LVRF
bit in the SMOD1 register will also be set to1.
F
or a valid LVR signal, a low voltage, i.e., a voltage
in the range between 0.9V~ V
LVR
must exist for greater than the value t
LVR
specified in the A.C.
characteristics. If the low voltage state does not exceed this value, the LVR will ignore the low
supply voltage and will not perform a reset function. The actual V
LVR
is 2.1V, the LVR will reset the
device after 2~3 LIRC clock cycles. Note that the LVR function will be automatically disabled when
the device enters the SLEEP/IDLE mode.
Note:t
RSTD
is power-on delay, typical time=50ms
Low Voltage Reset Timing Chart
