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3.3 Peripheral Pin Multiplexing Control
TMS320C6727, TMS320C6726, TMS320C6722
Floating-Point Digital Signal Processors
SPRS268E – MAY 2005 – REVISED JANUARY 2007
Table 3-3
lists the options for configuring the SPI1, McASP0, and McASP1 pins. Note that there are
additional finer grain options when selecting which McASP controls the particular AXR serial data pins but
these options are not listed here and can be made on a pin by pin basis.
Table 3-3. Options for Configuring SPI1, McASP0, and McASP1 Data Pins
CONFIGURATION
OPTION 1
OPTION 2
OPTION 3
OPTION 4
OPTION 5
PERIPHERAL
SPI1
5-pin mode
4-pin mode
4-pin mode
3-pin mode
disabled
McASP0
11
12
12
13
16
(max data pins)
McASP1
4
4
4
4
6
(max data pins)
PINS
AXR0[5]/
SPI1_SCS
SPI1_SCS
AXR0[5]
AXR0[5]
AXR0[5]
SPI1_SCS
AXR0[6]/
SPI1_ENA
AXR0[6]
SPI1_ENA
AXR0[6]
AXR0[6]
SPI1_ENA
AXR0[7]/
SPI1_CLK
SPI1_CLK
SPI1_CLK
SPI1_CLK
AXR0[7]
SPI1_CLK
AXR0[8]/AXR1[5]/
SPI1_SOMI
SPI1_SOMI
SPI1_SOMI
SPI1_SOMI
AXR0[8] or AXR1[5]
SPI1_SOMI
AXR0[9]/AXR1[4]/
SPI1_SIMO
SPI1_SIMO
SPI1_SIMO
SPI1_SIMO
AXR0[9] or AXR1[4]
SPI1_SIMO
Table 3-4
lists the options for configuring the shared EMIF and UHPI pins.
Table 3-4. Options for Configuring EMIF and UHPI (C6727 Only)
CONFIGURATION
OPTION 1
OPTION 2
PERIPHERAL
UHPI
Multiplexed Address/Data Mode, Fullword, or Non-Multiplexed Address/Data Mode
Half-Word
Fullword
EMIF
32-bit EMIF Data
16-bit EMIF Data
PINS
EM_D[31:16]/
EM_D[31:16]
UHPI_HA[15:0]
UHPI_HA[15:0]
While
Section 3.2
describes at a high level the most common pin multiplexing options, the control of pin
multiplexing is largely determined on an individual pin-by-pin basis. Typically, each peripheral that shares
a particular pin has internal control registers to determine the pin function and whether it is an input or an
output.
The C672x device determines whether a particular pin is an input or output based upon the following
rules:
•
The pin will be configured as an output if it is configured as an output in any of the peripherals sharing
the pin.
•
It is recommended that only one peripheral configure a given pin as an output. If more than one
peripheral does configure a particular pin as an output, then the output value is controlled by the
peripheral with highest priority for that pin. The priorities for each pin are given in
Table 3-5
.
•
The value input on the pin is passed to all peripherals sharing the pin for input simultaneously.
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Device Configurations
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