Analog to Digital (ATD) Module
MC1321x Reference Manual, Rev. 1.6
Freescale Semiconductor
20-9
20.4
Resets
The ATD module is reset on system reset. If the system reset signal is activated, the ATD registers are
initialized back to their reset state and the ATD module is powered down. This occurs as a function of the
register file initialization; the reset definition of the ATDPU bit (power down bit) is zero or disabled.
The MCU places the module back into an initialized state. If the module is performing a conversion, the
current conversion is terminated, the conversion complete flag is cleared, and the SAR register bits are
cleared. Any pending interrupts are also cancelled. Note that the control, test, and status registers are
initialized on reset; the initialized register state is defined in the register description section of this
specification.
Enabling the module (using the ATDPU bit) does not cause the module to reset since the register file is not
initialized. Finally, writing to control register ATD1C does
not cause the module to reset; the current
conversion will be terminated.
20.5
Interrupts
The ATD module originates interrupt requests and the MCU handles or services these requests. Details on
how the ATD interrupt requests are handled can be found in
Chapter 12, “MCU Resets, Interrupts, and
.
The ATD interrupt function is enabled by setting the ATDIE bit in the ATD1SC register. When the ATDIE
bit is set, an interrupt is generated at the end of an ATD conversion and the ATD result registers (ATD1RH
and ATD1RL) contain the result data generated by the conversion. If the interrupt function is disabled
(ATDIE = 0), then the CCF flag must be polled to determine when a conversion is complete.
The interrupt will remain pending as long as the CCF flag is set. The CCF bit is cleared whenever the ATD
status and control (ATD1SC) register is written. The CCF bit is also cleared whenever the ATD result
registers (ATD1RH or ATD1RL) are read.
20.6
ATD Registers and Control Bits
The ATD has seven registers which control ATD functions.
Refer to the direct-page register summary in
for the absolute address
assignments for all ATD registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
Table 20-2. Interrupt Summary
Interrupt
Local
Enable
Description
CCF
ATDIE
Conversion complete
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