SPRUJF2A March 2026 – March 2026 AM13E23019
The IOMUX manages the selection of which peripheral function is to be used on a digital IO. IOMUX also provides the controls for the output driver, input path, and the wakeup logic for wakeup from SHUTDOWN mode.
There are several digital IO types which can be included on a given device. Each digital IO type supports different features. Digital IO Features by IO Type lists the features which are included with each IO type. See the device-specific data sheet for which IO type is used on a given package pin.
| IO Structure | Inversion Control | Drive Strength Control | Pullup Resistor | Pulldown Resistor | Wakeup Logic |
|---|---|---|---|---|---|
| Standard-drive (SDIO) | Y | Y | Y | ||
| Standard-drive with wake (SDIO) | Y | Y | Y | Y | |
| High-drive (HDIO) | Y | Y | Y | Y | |
| High-speed (HSIO) | Y | Y | Y | Y |
Certain pins on a device are digital only and do not have any analog functions connected to the pin. Other pins can have one or more analog functions connected to the pin in addition to the digital IO functions. Analog functions are never selected within the IOMUX; these are always configured within of the respective analog peripheral. Analog peripherals have no knowledge of, or interaction with, the IOMUX.
In general, when analog functionality is used on a pin which also has digital functions, the IOMUX configuration for that pin must be left in the default (high-Z) state so as to not interfere with the proper operation of the analog function. However, it is possible to have the IOMUX active on a pin when an analog peripheral is also interacting with the pin, provided that the application software verifies there is not a conflict between the functions. For example, it is possible to have the pullup or pulldown resistor on an IO enabled at the same time that the ADC is running a conversion on the same IO. However, an invalid configuration of enabling the output driver on an IO at the same time that an analog peripheral is driving the IO (for example, a CMPSSx_DACL or PGAx output). This creates an IO conflict.
Application software is responsible for making sure that the IOMUX settings do not conflict with any analog peripheral functions which can be enabled on a shared pad.
The mixed-signal IO pin slice diagram for a full featured IO pin is shown in Superset IO Slice. Not all pins have analog functions, wake-up logic, drive strength control, and pullup or pulldown resistors available. See the Pin Configuration and Functions table within the device-specific data sheet for detailed information on what features and peripherals are supported on a specific pin. An example for a single pin is shown below in IOMUX Pin Example.
| PINCMx | Pin Name | Analog [MuxMode] | Digital [MuxMode] | IO Structure |
|---|---|---|---|---|
| IOMUX_PA2 | PA2 | Unconnected | Unconnected | High-Drive |
| ANALOG_AIN8 [ANALOG] | GPIO02 [1] | |||
| A0_3 [A0] | MCPWM4_2A [2] | |||
| CMP1_HN0 [A1] | MCPWM3_1B [3] | |||
| PGA0_OUT [A2] | MCPWM3_3A [4] | |||
| MCPWM4_3A [5] | ||||
| MCPWM4_2B [6] | ||||
| UC1_TX_SDA_PICO [7] | ||||
| MCPWM3_1A [8] | ||||
| UC0_TX_SDA_PICO [11] | ||||
| OUTPUTXBAR5 [14] |
The initial state of the IOMUX pin slice for all digital IO after a BOOTRST is as follows: