1.4.5 GPIO and Peripheral Multiplexing (MUX)
Up to three different peripheral functions are multiplexed along with a general input/output (GPIO) function per
pin. This allows you to pick and choose a peripheral mix that will work best for the particular application.
show an overview of the possible multiplexing combinations sorted by GPIO pin. The
second column indicates the I/O name of the pin on the device. Since the I/O name is unique, it is the best way
to identify a particular pin. Therefore, the register descriptions in this section only refer to the GPIO name of a
particular pin. The MUX register and particular bits that control the selection for each pin are indicated in the first
column.
For example, the multiplexing for the GPIO6 pin is controlled by writing to GPAMUX[13:12]. By writing to these
bits, the pin is configured as either GPIO6, or one of up to three peripheral functions. The GPIO6 pin can be
configured as follows:
GPAMUX1[13:12] Bit Setting
Pin Functionality Selected
If GPAMUX1[13:12] = 0,0
Pin configured as GPIO6
If GPAMUX1[13:12] = 0,1
Pin configured as EPWM4A (O)
If GPAMUX1[13:12] = 1,0
Pin configured as EPWMSYNCI (I)
If GPAMUX1[13:12] = 1,1
Pin configured as EPWMSYNCO (O)
The devices have different multiplexing schemes. If a peripheral is not available on a particular device, that MUX
selection is reserved on that device and should not be used.
Note
If you should select a reserved GPIO MUX configuration that is not mapped to a peripheral, the
state of the pin will be undefined and the pin may be driven. Reserved configurations are for future
expansion and should not be selected. In the device MUX tables (
) these
options are indicated as Reserved.
Some peripherals can be assigned to more than one pin via the MUX registers. For example, the SPISIMOB can
be assigned to either the GPIO12 or GPIO24 pin, depending on individual system requirements as shown.
Pin Assigned to SPISIMOB
MUX Configuration
Choice 1
GPIO12
GPAMUX1[25:24] = 11
or Choice 2
GPIO24
GPAMUX2[17:16] = 11
If no pin is configured as an input to a peripheral, or if more than one pin is configured as an input for the same
peripheral, then the input to the peripheral will either default to a 0 or a 1 as shown in
. For example,
if SPISIMOB were assigned to both GPIO12 and GPIO24, the input to the SPI peripheral would default to a high
state as shown in
and the input would not be connected to GPIO12 or GPIO24.
System Control and Interrupts
120
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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