S12 Clock, Reset and Power Management Unit (S12CPMU)
7.6.1.4
Low-Voltage Interrupt (LVI)
In FPM the input voltage V
is monitored. Whenever V
drops below level V
the status bit
DDA
DDA
LVIA,
LVDS is set to 1. On the other hand, LVDS is reset to 0 when V
rises above level V
. An interrupt,
LVID
DDA
indicated by flag LVIF = 1, is triggered by any change of the status bit LVDS if interrupt enable bit LVIE
= 1.
7.6.1.5
HTI - High Temperature Interrupt
In FPM the junction temperature T is monitored. Whenever T exceeds level T the status bit HTDS
HTIA
J
J
is set to 1. Vice versa, HTDS is reset to 0 when T get below level T
. An interrupt, indicated by flag
J
HTID
HTIF = 1, is triggered by any change of the status bit HTDS, if interrupt enable bit HTIE = 1.
7.6.1.6
Autonomous Periodical Interrupt (API)
The API sub-block can generate periodical interrupts independent of the clock source of the MCU. To
enable the timer, the bit APIFE needs to be set.
The API timer is either clocked by a trimmable internal RC oscillator (ACLK) or the Bus Clock. Timer
operation will freeze when MCU clock source is selected and Bus Clock is turned off. The clock source
can be selected with bit APICLK. APICLK can only be written when APIFE is not set.
The APIR[15:0] bits determine the interrupt period. APIR[15:0] can only be written when APIFE is
cleared. As soon as APIFE is set, the timer starts running for the period selected by APIR[15:0] bits. When
the configured time has elapsed, the flag APIF is set. An interrupt, indicated by flag APIF = 1, is triggered
if interrupt enable bit APIE = 1. The timer is re-started automatically again after it has set APIF.
The procedure to change APICLK or APIR[15:0] is first to clear APIFE, then write to APICLK or
APIR[15:0], and afterwards set APIFE.
The API Trimming bits APITR[5:0] must be set so the minimum period equals 0.2 ms if stable frequency
is desired.
See Table 7-17 for the trimming effect of APITR.
NOTE
The first period after enabling the counter by APIFE might be reduced by
API start up delay t
.
sdel
It is possible to generate with the API a waveform at the external pin API_EXTCLK by setting APIFE and
enabling the external access with setting APIEA.
7.7
Initialization/Application Information
S12P-Family Reference Manual, Rev. 1.13
250
Freescale Semiconductor
FREESCALE [ Freescale ]
