FXTH870xD
Sensors
38
Freescale Semiconductor, Inc.
5.10
Temperature Sensor and Restart System
The FXTH870xD has two temperature sensing mechanisms. The first is an accurate sensor which is accessible through the
ADC10 channel 1. The second is a less accurate, very low power sensor which generates a wakeup from STOP1 when the
temperature crosses its threshold of detection. This is the temperature restart wakeup which is used as follows:
1.
The temperature restart wakeup is enabled by software following detection of an over temperature condition using the
temperature sensor connected to the ADC10.
2.
User software enables the temperature restart detector and then instructs the MCU to enter STOP1 mode to halt
execution during the out-of-range temperature condition.
3.
When the temperature crosses the temperature restart threshold back into the normal range of operation, a wakeup is
generated to wake the MCU. Exit from STOP1 will reset the device.
The temperature sensor is enabled whenever the ADC10 is enabled. The temperature restart wakeup is enabled by setting the
TRE bit in SIMOPT1 register and whether the detector interrupts the MCU from a very low or a very high temperature is
determined by the TRH bit in the SIMOPT1 register.
5.11
Reset, Interrupt and System Control Registers And Bits
One 8-bit register in the direct page register space and eight 8-bit registers in the high-page register space are related to reset
and interrupt systems.
5.11.1
System Reset Status Register (SRS)
The SRS register at $1800 includes seven read-only status flags to indicate the source of the most recent reset. When a debug
host forces reset by writing 1 to BDFR in the SBDFR register, none of the status bits in SRS will be set. Writing any value to this
register address clears the COP watchdog timer without affecting the contents of this register. The reset state of these bits
depends on what caused the MCU to reset.
Table 24. Real-Time Interrupt Period
RTIS2
RTIS1
RTIS0
Delay Timing (ms)
(Dependent on 1-kHz LFO)
0
0
0
OFF
0
0
1
2
0
1
0
4
0
1
1
8
1
0
0
16
1
0
1
32
1
1
0
64
1
1
1
128
$1800
Bit 7
6
5
4
3
2
1
Bit 0
R
POR
PIN
COP
ILOP
ILAD
PWU
LVD
0
W
POR Reset:
1
0
0
0
0
0
1
0
LVD Reset:
1
0
0
0
0
0
1
0
Any Other
Reset:
0
0
0
0
= Reserved
1. Any of these reset sources that are active at the time of reset will cause the corresponding bit(s) to be set; bits corresponding to sources that
are not active at the time of reset will be cleared.
Figure 21. System Reset Status Register (SRS)
Содержание FXTH870 D Series
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