C8051F850-C-GM Datasheet, PDF (200/328 Pages) Silicon Laboratories – Low-Cost 8-bit MCU Family with up to 8 kB of Flash

21.2.3. 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 21.3 shows all available fixed digital functions and the potential
mapping of port I/O to each function.
Table 21.3. Port I/O Assignment for Fixed Digital Functions
Function
Potentially Assignable Port Pins
SFR(s) used for
Assignment
External Interrupt 0
External Interrupt 1
Conversion Start (CNVSTR)
External Clock Input (EXTCLK)
Port Match
P0.0 - P0.7
P0.0 - P0.7
P0.6
P0.3
P0.0 - P1.7
IT01CF
IT01CF
ADC0CN
OSCXCN
P0MASK, P0MAT
P1MASK, P1MAT
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