PXS20RM Datasheet, PDF (200/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Analog-to-Digital Converter (ADC)
• For ADC_0:
— VREFH ADC_0 = presampling channel 0
— VREFL ADC_0 = presampling channel 1
• For ADC_1:
— VREFH ADC_1 = presampling channel 0
— VREFL ADC_1 = presampling channel 1
9.4.6 Programmable analog watchdog
9.4.6.1 Introduction
The analog watchdogs are used for determining whether the result of a channel conversion lies within a
given guarded area (as shown in Figure 9-48) specified by an upper and a lower threshold value named
THRH and THRL respectively.
Analog voltage
Upper threshold
Lower threshold
Guarded area
THRH
THRL
Figure 9-48. Guarded area
After the conversion of the selected channel, a comparison is performed between the converted value and
the threshold values. If the converted value lies outside that guarded area then corresponding threshold
violation interrupts are generated. The comparison result is stored as WDGxH and WDGxL bits in the
WTISR as explained in Table 9-44. Depending on the mask bits MSKWDGxL and MSKWDGxH in the
WTIMR, an interrupt is generated on threshold violation.
Table 9-44. Values of WDGxH and WDGxL fields
WDGxH
1
0
0
WDGxL
0
1
0
Converted data
converted data > THRH
converted data < THRL
THRL  converted data  THRH
NOTE
Avoid the situation where THRH < THRL. In this case, a WDGxH or
WDGxL interrupt will always be generated, and this could lead to
misinterpretation of the watchdog interrupts.
9-42
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor