PXN20RM Datasheet, PDF (1130/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Analog-to-Digital Converter (ADC)
The logic configuration for selecting the threshold values for the analog watchdog is shown in
Figure 34-50. After the conversion of the selected channel a comparison is performed between the
converted value obtained and the threshold values set. The result is stored as WDGnH and WDGnL bits
in the WTISR register as explained in Table 34-43. Depending on the MSKWDGnL and MSKWDGnH
mask bits in the WTIMR register, an interrupt is generated on threshold violation.
Table 34-43. Values of WDGnH and WDGnL Fields
WDGnH
1
0
0
WDGnL
0
1
0
Converted data
converted data > THRH
converted data < THRL
THRH < converted data < THRL
THRHn
THRH_ALTn
0
1
Upper Threshold for conversion
THRHn
THRH_ALTn
Analog Watchdog n
0
1
Lower Threshold for conversion
alternate_wdgbus(x)
Setting Upper and Lower Threshold values for the analog watchdog [n = (0 ... 3)]
Figure 34-49. Alternate Watchdog Threshold Configuration
Analog Voltage
Upper threshold
Lower threshold
Guarded area
THRH
THRL
Figure 34-50. Guarded Area
34-50
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor