8.3 Operation
8.3.1 Overview
The SCI supports serial data transfer in two modes. In asynchronous mode each character is
synchronized individually. In synchronous mode communication is synchronized with a clock
signal.
The selection of asynchronous or synchronous mode and the communication format depend on
settings in the SMR as indicated in table 8-5. The clock source depends on the settings of the C/A
bit in the SMR and the CKE1 and CKE0 bits in the SCR as indicated in table 8-6.
(1) Asynchronous Mode:
•
Data lengths of seven or eight bits can be selected.
•
A parity bit or multiprocessor bit can be added, and stop bit lengths of one or two bits can be
selected. These selections determine the communication format and character length.
•
Framing errors (FER), parity errors (PER) and overrun errors (ORER) can be detected in
receive data, and the line-break condition can be detected.
•
An internal or external clock source can be selected for the serial clock.
•
When an internal clock source is selected, the SCI is clocked by the on-chip baud rate generator
and can output a clock signal at the bit-rate frequency.
•
When the external clock source is selected, the on-chip baud rate generator is not used. The
external clock frequency must be 16 times the bit rate.
(2) Synchronous Mode:
•
The transmit data length is eight bits.
•
Overrun errors (ORER) can be detected in receive data.
•
An internal or external clock source can be selected for the serial clock.
•
When an internal clock source is selected, the SCI is clocked by the on-chip baud rate generator
and outputs a serial clock signal.
•
When the external clock source is selected, the on-chip baud rate generator is not used and the
SCI operates on the input serial clock.
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Summary of Contents for H8/326 Series
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