NXP Semiconductors MPC5606S - Programmable Analog Watchdog

Analog-to-Digital Converter (ADC)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 137
5.3.4 Programmable analog watchdog
5.3.4.1 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 5-4) specified by an upper and a lower threshold value named
THRH and THRL respectively.
Figure 5-4. 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 5-4. Depending on the mask bits MSKWDGxL and MSKWDGxH in the
WTIMR, an interrupt is generated on threshold violation.
The channel on which the analog watchdog is to be applied is selected by the THRCH field in the TRC
registers. The analog watchdog is enabled by setting the corresponding THREN bit in the same register.
1 11 1111 1101 252 × Tck 30 × Tck 1 × Tck 283 × Tck
1 11 1111 1110 253 × Tck 30 × Tck 1 × Tck 284 × Tck
1 11 1111 1111 254 × Tck 30 × Tck 1 × Tck 285 × Tck
1
Represents the number of clock cycles that this operation will last
2
The ADC minimum conversion time at 60 MHz frequency is 39 × Tck; that corresponds to 650 ns.
Table 5-4. Values of WDGxH and WDGxL fields
WDGxH WDGxL Converted data
1 0 converted data > THRH
0 1 converted data < THRL
0 0 THRL <= converted data <= THRH
Table 5-3. ADC sampling and conversion timing (continued)
INPLATCH INPCMP INPSAMP T
sample
1
T
eval
ndelay T
conv
THRH
THRL
Analog voltage
Upper threshold
Lower threshold
Guarded area