3 Secondary Digital Functions on DVIO Supplied I/Os

The DVIO supplied general-purpose I/Os are multiplexed with other digital functions in the device, and these digital functions’ I/O circuits are also powered from DVIO. On the F522x and F521x devices, some of the secondary digital functions that are shared with the DVIO supplied I/Os include timer capture compare functions, serial communication functions (USCI UART, SPI, or I²C), comparator output, SMCLK output, and MCLK output. See the signal descriptions table in MSP430F522x, MSP430F521x Mixed-Signal Microcontrollers for details.

On the F522x and F521x devices, Port 4 supports port mapping and resides on the DVIO supply domain. Any of the secondary digital functions specified in the port mapping table can be mapped to Port4, and their respective I/O circuitry is supplied by DVIO. See the port mapping table in the Peripherals section of the data sheet for details.

NOTE

In split supply I/O systems, if external pullup resistors are connected to any of the DVIO supplied pins (for example, the USCI I²C pins – SDA and SCL), tie the external pullups to the DVIO supply and not to DVCC.

Other DVIO supplied digital pins on the F522x and F521x devices include:

• BSLEN – BSL enable pin used by the DVIO supplied BSL interface (see Section 7). By default, this pin has a nonconfigurable internal pulldown resistor enabled.
• RST/NMI – DVIO supplied reset pin multiplexed with NMI functionality. See Section 5 for details of the reset functionality.