c8051f410 Silicon Laboratories, c8051f410 Datasheet - Page 147

• Manufacturer Part Number: c8051f410
• Description: 2.0 V, 32/16 Kb Flash, Smartclock, 12-bit Adc
• Manufacturer: Silicon Laboratories

18. Port Input/Output
Digital and analog resources are available through up to 24 I/O pins. Port pins are organized as three byte-
wide Ports. Each of the Port pins can be defined as general-purpose I/O (GPIO) or analog input/output;
Port pins P0.0 - P2.7 can be assigned to one of the internal digital resources as shown in Figure 18.3. The
designer has complete control over which functions are assigned, limited only by the number of physical
I/O pins. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder.
Note that the state of a Port I/O pin can always be read in the corresponding Port latch, regardless of the
Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the peripheral priority
order of the Priority Decoder (Figure 18.3 and Figure 18.4). The registers XBR0 and XBR1, defined in SFR
Definition 18.1 and SFR Definition 18.2, are used to select internal digital functions.
Port I/Os on P0 are 5 V tolerant over the operating range of V
driven above V
configured as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n =
0,1,2). Complete Electrical Specifications for Port I/O are given in Table 18.1 on page 163.
Highest
Priority
Lowest
Priority
SYSCLK
Outputs
IO
SMBus
T0, T1
UART
P0
P1
P2
PCA
CP0
CP1
SPI
or they will sink current. Figure 18.2 shows the Port cell circuit. The Port I/O cells are
(P0.0-P0.7)
(P1.0-P1.7)
(P2.0-P2.7)
Figure 18.1. Port I/O Functional Block Diagram
2
4
2
4
7
2
8
8
8
Rev. 1.0
PnSKIP Registers
XBR0, XBR1,
Crossbar
Decoder
Priority
Digital
IO
. Port I/Os on P1 and P2 should not be
8
8
8
P0MASK, P0MATCH
P1MASK, P1MATCH
C8051F410/1/2/3
Registers
Cells
Cells
Cell
I/O
I/O
I/O
P0
P1
P2
P2.3–2.6 available on
PnMDIN Registers
C8051F410/2
PnMDOUT,
P0.0
P0.7
P1.0
P1.7
P2.0
P2.7
147