MAC7200 datasheet(819/976 Pages) FREESCALE

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The DMADC1032 Module

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

741

NOTE

All PIT timers, except the RTI, run off of the Peripheral Bus Clock, which

is 1/2 the frequency of the System Clock.

If SYSTRIG0 should trigger a conversion, write the reload value to the timer load value register for timer

10 and enable this timer.

If SYSTRIG1 should trigger a conversion, write the reload value to the timer load value register for timer

9 and enable this timer.

In the ATD you must perform the following steps in order to use a system trigger (it is assumed that all

other registers in the ATD are already configured):

1. ATD: Clear MDIS bit

2. ATD: Write $06 to the ATDTRIGCTL register. This selects rising edge sensitivity for SYSTRIG0.

3. ATD: Write $0C to the ATDTRIGCTL register. This selects rising edge sensitivity for SYSTRIG1.

4. ATD: Write a command word to the ATDCW register that has the bits CWCM set to ’10’ (wait for

trigger)

After the write of the command word to the ATDCW register is performed, the ATD will start the

conversion when the trigger is asserted.

NOTE

Be aware that a new command word must be provided before the next

trigger is asserted. Otherwise the ETO-flag in the ATDFLAG register will

be set.

33.8

The DMADC1032 Module

33.8.1

Overview

The DMADC1032 is a 32-channel multiplexed input analog-to-digital converter (ATD) with a resolution

of 12 bits. Please refer to Device Electrical Specifications for ATD electrical parameters.

The ATD module can be configured to enable the conversion results to be moved from the result register

to system memory without the intervention of the core by using a DMA channel. ATD conversions are

controlled using a command word which determines aspects of the conversion such as the channel to be

converted or any trigger source used to start the conversion. A DMA channel can also be used to provide

a sequence of conversion commands enabling the device to queue up conversion sequences.

Conversions can be started either under the direct control of the ATD module, or by a trigger source. The

trigger source can be external to the device, using one of the analog channel pins as its input. It can also

be one of the two device-internal programmable timers.

MAC7200 Datasheet(PDF) 819 Page - Freescale Semiconductor, Inc