C8051F970-A-GM Datasheet, PDF (280/454 Pages) Silicon Laboratories – Low Power Capacitive Sensing MCU with up to 32 kB of Flash

C8051F97x
26.2.2. Assigning Port I/O Pins to Digital Functions
Any port pins not assigned to analog functions may be assigned to digital functions or used as GPIO. Most digital
functions rely on the crossbar for pin assignment; however, some digital functions bypass the crossbar in a manner
similar to the analog functions listed above. Table 26.2 shows all digital functions available through the crossbar
and the potential mapping of port I/O to each function.
Table 26.2. Port I/O Assignment for Digital Functions
Digital Function
SMBus0, UART0, SPI0, SYSCLK,
PCA0 (CEX0-2 and ECI), T0, or T1.
Potentially Assignable Port Pins
QFN-48
QFN-32
QFN-28
Any port pin available for assignment by the
crossbar. This includes P0.0 – P2.7 pins which
have their PnSKIP bit set to ‘0’.
SFR(s) Used for
Assignment
XBR0, XBR1, XBR2
Any pin used for GPIO
P0.0 – P5.2,
P6.0 – P6.1
P0.0 – P3.2,
P5.2,
P6.0 – P6.1
P0.0 – P2.1,
P5.2,
P6.0 – P6.1
P0SKIP, P1SKIP,
P2SKIP
26.2.3. Assigning Port I/O Pins to Fixed Digital Functions
Fixed digital functions include external clock input as well as external event trigger functions, which can be used to
trigger events such as an ADC conversion, fire an interrupt or wake the device from idle mode when a transition
occurs on a digital I/O pin. The fixed digital functions do not require dedicated pins and will function on both GPIO
pins and pins in use by the crossbar. Fixed digital functions cannot be used on pins configured for analog I/O.
Table 26.3 shows all available fixed digital functions and the potential mapping of port I/O to each function.
Table 26.3. Port I/O Assignment for Fixed Digital Functions
Function
External Interrupt 0
External Interrupt 1
Potentially Assignable Port Pins
QFN-48
QFN-32
QFN-28
P0.0 - P0.7
P0.0 - P0.7
SFR(s) used for
Assignment
IT01CF
IT01CF
Conversion Start (CNVSTR)
Port Match
I2C Slave 0
P0.0 - P2.7
P0.6
P0.0 - P2.7
P0.0 - P2.1
P6.0, P6.1
ADC0CN
P0MASK, P0MAT
P1MASK, P1MAT
P2MASK, P2MAT
I2C0CN
Rev 1.0
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