Datasheet

ST10F269 12 - PARALLEL PORTS
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12.6.1 - Alternate Functions of Port 3
The pins of Port 3 serve for various functions which include external timer control lines, the two serial
interfaces and the control lines BHE
/WRH and CLKOUT.
The structure of the Port 3 pins depends on their
alternate function (see figures Figure 28 and
Figure 29). When the on-chip peripheral
associated with a Port 3 pin is configured to use
the alternate input function, it reads the input
latch, which represents the state of the pin, via the
line labeled “Alternate Data Input”. Port 3 pins with
alternate input functions are: T0IN, T2IN, T3IN,
T4IN, T3EUD and CAPIN.
When the on-chip peripheral associated with a
Port 3 pin is configured to use the alternate output
function, its “Alternate Data Output” line is ANDed
with the port output latch line. When using these
alternate functions, the user must set the direction
of the port line to output (DP3.y=1) and must set
the port output latch (P3.y=1). Otherwise the pin is
in its high-impedance state (when configured as
input) or the pin is stuck at '0' (when the port
output latch is cleared). When the alternate output
functions are not used, the “Alternate Data
Output” line is in its inactive state, which is a high
level ('1').
Port 3 pins with alternate output functions are:
T6OUT, T3OUT, TxD0, BHE
and CLKOUT.
Table 20 : Port 3 Alternative Functions
Port 3 Pin Alternate Function
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
P3.8
P3.9
P3.10
P3.11
P3.12
P3.13
P3.14
P3.15
T0IN CAPCOM1 Timer 0 Count Input
T6OUT Timer 6 Toggle Output
CAPIN GPT2 Capture Input
T3OUT Timer 3 Toggle Output
T3EUD Timer 3 External Up/Down Input
T4IN Timer 4 Count Input
T3IN Timer 3 Count Input
T2IN Timer 2 Count Input
MRST SSC Master Receive / Slave Transmit
MTSR SSC Master Transmit / Slave Receive
TxD0 ASC0 Transmit Data Output
RxD0 ASC0 Receive Data Input (Output in synchronous mode)
BHE
/WRH Byte High Enable / Write High Output
SCLK SSC Shift Clock Input/Output
--- No pin assigned
CLKOUT System Clock Output
Figure 27 : Port 3 I/O and Alternate Functions
Port 3
No Pin
Alternate Function a) b)
General Purpose Input/Output
P3.15
P3.13
P3.12
P3.11
P3.10
P3.9
P3.8
P3.7
P3.6
P3.5
P3.4
P3.3
P3.2
P3.1
P3.0
CLKOUT
SCLK
BHE
RxD0
TxD0
MTSR
MRST
T2IN
T3IN
T4IN
T3EUD
T3OUT
CAPIN
T6OUT
T0IN
WRH