C8051F70X_0910 Datasheet, PDF (168/290 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F70x/71x
26.1.4. Increasing Port I/O Drive Strength
Port I/O output drivers support a high and low drive strength; the default is low drive strength. The drive
strength of a Port I/O can be configured using the PnDRV registers. See Section “7. Electrical Characteris-
tics” on page 39 for the difference in output drive strength between the two modes.
26.2. Assigning Port I/O Pins to Analog and Digital Functions
Port I/O pins P0.0–P2.7 can be assigned to various analog, digital, and external interrupt functions. The
Port pins assigned to analog functions should be configured for analog I/O, and Port pins assigned to digi-
tal or external interrupt functions should be configured for digital I/O.
26.2.1. Assigning Port I/O Pins to Analog Functions
Table 26.1 shows all available analog functions that require Port I/O assignments. Port pins selected for
these analog functions should have their corresponding bit in PnSKIP set to 1. This reserves the pin
for use by the analog function and does not allow it to be claimed by the Crossbar. Table 26.1 shows the
potential mapping of Port I/O to each analog function.
Table 26.1. Port I/O Assignment for Analog Functions
Analog Function
ADC Input
Potentially Assignable
Port Pins
P0.0–P2.7
Comparator0 Input
P0.0–P1.7
CS0 Input
Voltage Reference (VREF0)
P2.0–P5.7
P0.0
Ground Reference (AGND)
External Oscillator in Crystal Mode (XTAL1)
P0.1
P0.2
External Oscillator in RC, C, or Crystal Mode (XTAL2)
P0.3
SFR(s) used for
Assignment
AMX0P, AMX0N,
PnSKIP, PnMDIN
CPT0MX, PnSKIP,
PnMDIN
PnMDIN
REF0CN, P0SKIP,
PnMDIN
REF0CN, P0SKIP
OSCXCN, P0SKIP,
P0MDIN
OSCXCN, P0SKIP,
P0MDIN
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Rev. 0.3