ROHS MC9S08QE128 Reference Manual page 178

Chapter 10 Analog-to-Digital Converter (S08ADC12V1)
10.1.2.3 Hardware Trigger
The ADC may initiate a conversion via software or a hardware trigger. The RTC can be enabled as the
hardware trigger for the ADC module by setting ADCSC2[ADTRG]. When enabled, the ADC is triggered
each time RTCINT matches RTCMOD. The RTC interrupt does not have to be enabled to trigger the ADC.
The RTC can be configured to cause a hardware trigger in MCU run, wait, and stop3.
10.1.2.4 Temperature Sensor
The ADC module includes a temperature sensor whose output is connected to one of the ADC analog
channel inputs. Equation 10-1
where:
— V is the voltage of the temperature sensor channel at the ambient temperature.
TEMP
— V is the voltage of the temperature sensor channel at 25°C.
TEMP25
— m is the hot or cold voltage versus temperature slope in V/°C.
For temperature calculations, use the V
In application code, the user reads the temperature sensor channel, calculates V
V . If V is greater than V
TEMP25 TEMP
less than V the hot slope value is applied in
TEMP25
178
provides an approximate transfer function of the temperature sensor.
V
TEMP
Temp = 25
– ---------------------------------------------- -
and m values in the data sheet.
TEMP25
the cold slope value is applied in
TEMP25
MC9S08QE128 MCU Series Reference Manual, Rev. 2
V
–
TEMP25
m
Equation 10-1.
Eqn. 10-1
, and compares to
TEMP
Equation 10-1. If V
TEMP
Freescale Semiconductor
is