ADSP-2126x SHARC Processor Hardware Reference
8-19
Parallel Port
and
PPTX
. For all four of these methods, the core uses the same basic steps
to initiate the transfer. However, each method uses a different technique
to complete it. The following steps provide the basic procedure for setting
up and initiating a data transfer using the core.
1. Write the external byte address to the
EIPP
register and the external
address modifier to the
EMPP
register.
Before initializing or modifying any of the parallel port parameter
registers such as
EIPP
and
EMPP
, the parallel port must first be dis-
abled (bit 0,
PPEN
, of the
PPCTL
register must be cleared). Only
when
PPEN
=0, can those registers be modified and the port then
re-enabled. This sequence is most often used to perform
non-sequential, external transfers, such as when accessing taps in a
delay line.
For core-driven transfers, the
ECPP
,
IIPP
,
IMPP
, and
ICPP
are not
used. Although these registers are automatically updated by the
parallel port (the
ECPP
register decrements for example), they may
be left uninitialized without consequence.
2. Initialize the
PPCTL
register with the appropriate settings.
These include the parallel port data-cycle duration (
PPDUR
) and
whether the transfer is a receive or transmit operation (
PPTRAN
). For
core-driven transfers, be sure to clear the DMA enable bit,
PPDEN
.
In this same write to
PPCTL
, the port may also be enabled by setting
bit 0,
PPEN
, to 1.
When enabling the parallel port (setting
PPEN
= 1), the external bus activ-
ity varies, depending on the direction of data transfer (receive or
transmit). For transmit operations (
PPTRAN
= 1), the parallel port does not
perform any external accesses until valid data is written to the
TXPP
register
by the core.
For read operations (
PPTRAN
= 0), two core clock cycles after
PPEN
is set
(=1), the parallel port immediately fetches two 32-bit data words from the
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...