HCS08 datasheet(230/290 Pages) MOTOROLA

230 / 290 page

Analog-to-Digital Converter (ATD) Module

MC9S08GB/GT

230

MOTOROLA

14.4 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

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 ATDC does not cause the module to reset; the current

conversion will be terminated.

14.5 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 the Resets, Interrupts, and System

Configuration section.

The ATD interrupt function is enabled by setting the ATDIE bit in the ATDSC register. When the ATDIE

bit is set, an interrupt is generated at the end of an ATD conversion and the ATD result registers (ATDRH

and ATDRL) 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 (ATDSC) register is written. The CCF bit is also cleared whenever the ATD result

registers (ATDRH or ATDRL) are read.

14.6 ATD Registers and Control Bits

The ATD has seven registers which control ATD functions.

Refer to the direct-page register summary in the Memory section of this data sheet for the absolute address

assignments for all ATD registers. This section refers to registers and control bits only by their names. A

Motorola-provided equate or header file is used to translate these names into the appropriate absolute

addresses.

Table 14-2 Interrupt Summary

Interrupt

Local

Enable

Description

CCF

ATDIE

Conversion complete

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