Information

DMA_TCDn_BITER_ELINKNO field descriptions

Field Description

ELINK

Enables channel-to-channel linking on minor loop complete

As the channel completes the minor loop, this flag enables the linking to another channel, defined by

BITER[LINKCH]. The link target channel initiates a channel service request via an internal mechanism

that sets the TCDn_CSR[START] bit of the specified channel. If channel linking is disabled, the BITER

value extends to 15 bits in place of a link channel number. If the major loop is exhausted, this link

mechanism is suppressed in favor of the MAJORELINK channel linking.

NOTE: When the software loads the TCD, this field must be set equal to the corresponding CITER field.

Otherwise, a configuration error is reported. As the major iteration count is exhausted, the

contents of this field is reloaded into the CITER field.

0 The channel-to-channel linking is disabled

1 The channel-to-channel linking is enabled

14–0

BITER

Starting Major Iteration Count

As the transfer control descriptor is first loaded by software, this 9-bit (ELINK = 1) or 15-bit (ELINK = 0)

field must be equal to the value in the CITER field. As the major iteration count is exhausted, the contents

of this field are reloaded into the CITER field.

NOTE: When the software loads the TCD, this field must be set equal to the corresponding CITER field.

Otherwise, a configuration error is reported. As the major iteration count is exhausted, the

contents of this field is reloaded into the CITER field. If the channel is configured to execute a

single service request, the initial values of BITER and CITER should be 0x0001.

21.4 Functional description

21.4.1 eDMA basic data flow

The basic flow of a data transfer can be partitioned into three segments.

As shown in the following diagram, the first segment involves the channel activation:

Functional description

K20 Sub-Family Reference Manual, Rev. 2, Feb 2012

374 Freescale Semiconductor, Inc.