14.2 SCI signal descriptions
The SCI signals are shown in the table found here.
Table 14-1. SCI signal descriptions
Signal
Description
I/O
RxD
Receive data
I
TxD
Transmit data
I/O
14.2.1 Detailed signal descriptions
The detailed signal descriptions of the SCI are shown in the following table.
Table 14-2. SCI—Detailed signal descriptions
Signal
I/O
Description
RxD
I
Receive data. Serial data input to receiver.
State meaning
Whether RxD is interpreted as a 1 or 0 depends on the bit encoding
method along with other configuration settings.
Timing
Sampled at a frequency determined by the module clock divided by
the baud rate.
TxD
I/O
Transmit data. Serial data output from transmitter.
State meaning
Whether TxD is interpreted as a 1 or 0 depends on the bit encoding
method along with other configuration settings.
Timing
Driven at the beginning or within a bit time according to the bit
encoding method along with other configuration settings.
Otherwise, transmissions are independent of reception timing.
14.3 Register definition
The SCI has 8-bit registers to control baud rate, select SCI options, report SCI status, and
for transmit/receive data.
Refer to the direct-page register summary in the memory chapter of this document or the
absolute address assignments for all SCI registers. This section refers to registers and
control bits only by their names. An NXP-provided equate or header file is used to
translate these names into the appropriate absolute addresses.
SCI signal descriptions
MC9S08PA4 Reference Manual, Rev. 5, 08/2017
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NXP Semiconductors
Summary of Contents for MC9S08PA4
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