TMPM330 - Keil

9.3.2 Serial Clock Generation Circuit
Under development
This circuit generates basic transmit and receive clocks.
• I/O interface mode
TMPM330 (rev 0.4) 9-14
TMPM330
In the SCLK output mode with the SC0CR serial control register set to “0,” the
output of the previously mentioned baud rate generator is divided by 2 to generate the
basic clock.
In the SCLK input mode with SC0CR set to “1,” rising and falling edges are
detected according to the SC0CR setting to generate the basic clock.
• Asynchronous (UART) mode :
9.3.3 Receive Counter
9.3.4 Receive Control Unit
According to the settings of the serial control mode register SC0MOD0 , either
the clock from the baud rate register, the system clock (fSYS), the internal output signal of
the TMRB9 timer, or the external clock (SCLKO pin) is selected to generate the basic
clock, SIOCLK.
The receive counter is a 4-bit binary counter used in the asynchronous (UART) mode and is
up-counted by SIOCLK. Sixteen SIOCLK clock pulses are used in receiving a single data bit
while the data symbol is sampled at the seventh, eighth, and ninth pulses. From these three
samples, majority logic is applied to decide the received data.
• I/O interface mode:
In the SCLK output mode with SC0CR set to “0,” the RXD0 pin is sampled on the
rising edge of the shift clock output to the SCLK0 pin.
In the SCLK input mode with SC0CR set to “1,” the serial receive data RXD0 pin
is sampled on the rising or falling edge of SCLK input depending on the SC0CR
setting.
• Asynchronous (UART) mode:
The receive control unit has a start bit detection circuit, which is used to initiate receive
operation when a normal start bit is detected.
9.3.5 Receive Buffer
The receive buffer is of a dual structure to prevent overrun errors. The first receive buffer (a
shift register) stores the received data bit-by-bit. When a complete set of bits have been
stored, they are moved to the second receive buffer (SC0BUF). At the same time, the
receive buffer full flag (SC0MOD2 “RBFLL”) is set to “1” to indicate that valid data is stored
in the second receive buffer. However, if the receive FIFO is set enabled, the receive data is
moved to the receive FIFO and this flag is immediately cleared.
If the receive FIFO has been disabled (SCOFCNF = 0 and SC0MOD1
=01), the INTRX0 interrupt is generated at the same time. If the receive FIFO has been
enabled (SCNFCNF = 1 and SC0MOD1 = 01), an interrupt will be
generated according to the SC0RFC setting.
Serial Channel (SIO)