Scan Sequencing - NXP Semiconductors freescale KV4 Series Reference Manual

Table of Contents

Functional Description

CTRL1[DMAEN0] is set and CTRL3[DMASRC]=0 a DMA transfer of the result data is

initiated. The CTRL1[START0] bit and SYNC0 input are ignored while a scan is in

process. Scanning stops and cannot be initiated when the CTRL1 [STOP0] bit is set.

Parallel scans differ in that converter A performs up to eight samples (SAMPLE[0:7]) in

parallel with converter B (SAMPLE[8:15]). Constraints are as follows:

• SAMPLEs[0:7] can reference only the ANA[0:7] inputs.

• SAMPLEs[8:15] can reference only the ANB[0:7] inputs.

Within these constraints, any sample can reference any pin, and more than one sample

slot can reference the same sample and the same input. All samples have the full

functionality of offset subtraction and high/low limit compare. By default (when

CTRL2[SIMULT]=1), the scans in both converters are initiated when the

CTRL1[START0] bit is written with a 1 or when the CTRL1[SYNC0] bit has a value of

1 and the SYNC0 input goes high. The scan in both converters terminates when either

converter encounters a disabled sample slot. Completion of a scan triggers the

STAT[EOSI0] interrupt if the CTRL1[EOSIEN0] interrupt enable is set. If

CTRL1[DMAEN0] is set and CTRL3[DMASRC]=0 then a DMA transfer of the result

data is initiated. Samples are always taken simultaneously in both the A and B converters.

Setting the CTRL1 [STOP0] bit stops and prevents the initiation of scanning in both

Setting CTRL2[SIMULT]=0 (non-simultaneous mode) causes parallel scanning to

operate independently in the A and B converter. Each converter has its own set of

START, STOP, SYNC, DMAEN, and EOSIEN control bits, SYNC input, EOSI

interrupt, and CIP status indicators (suffix 0 for converter A and suffix 1 for converter B).

Though still operating in parallel, the scans in the A and B converter start and stop

independently according to their own controls and can be simultaneous, phase shifted, or

asynchronous depending on when scans are initiated on the respective converters. The A

and B converters can be of different length (still up to a maximum of 8) and each

converter's scan completes when a disabled sample is encountered in that converters

sample list only. CTRL1[STOP0] stops the A converter only and CTRL2[STOP1] stops

the B converter only. Looping scan modes iterate independently. Each converter

independently restarts its scan after completing its list or encountering a disabled sample

34.5.5 Scan Sequencing

The sequential and parallel scan modes fall into three types based on how they repeat:

• Once scan. A once scan executes a sequential or parallel scan only once each time it

is started. It differs from a triggered scan in that sync inputs must be re-armed after

KV4x Reference Manual, Rev. 2, 02/2015

Freescale Semiconductor, Inc.