Intel SA-1100 manual UTCR0, Tce Rce Sce Dss Sbs Oes

Peripheral Control Module

11.11.3.7Transmit Clock Edge Select (TCE)

When SCE=1, the transmit clock edge select (TCE) bit is used to select which edge of the clock input from the GPIO pin to use (rising or falling) to synchronously drive data onto the transmit pin. When TCE=0, each bit transmitted is driven on the rising edge of the sample input clock; when TCE=1, bits are driven on the clock’s falling edge. Note that the internal baud rate generator is not used in this mode. TCE is ignored when SCE=0.

The following table shows the bit locations corresponding to the seven different control bit fields within UART control register 0. The UART must be disabled (RXE=TXE=0) when changing the state of any bit within this register. The reset state of these control bits is unknown (indicated by question marks) and must be initialized before enabling the UART. Note that writes to bit 7 are ignored and reads return zero.

	Address: 0h 8005 0000				UTCR0			Read/Write
Bit	7		6	5	4	3	2	1		0
		Res	TCE	RCE	SCE	DSS	SBS		OES	PE
Reset		0	?	?	?	?	?		?	?

Bit	Name		Description
0	PE	Parity enable.
		0	– Parity checking on received data and parity generation on transmitted data is disabled.
		1	– Parity checking on received data and parity generation on transmitted data is enabled.
1	OES	Odd/even parity select.
		0	– Odd parity checking/generation selected. Parity error bit set if even number of ones
		counted in data field (including the parity bit).
		1	– Even parity checking/generation selected. Parity error bit set if odd number of ones
		counted in data field (including the parity bit).
2	SBS	Stop bit select.
		0	– One stop bit transmitted per frame.
		1	– Two stop bits transmitted per frame.
		Note: Receiver not affected by SBS; always checks for one stop bit.
3	DSS	Data size select.
		0	– 7-bit data.
		1	– 8-bit data.
		Note: For 7-bit mode, the data is right justified within the FIFO entries, the MSBs in the
		receive FIFO are zero filled, and the MSBs in the transmit FIFO are ignored.
4	SCE	Sample clock enable.
		0	– on-chip baud rate generator and digital PLL used to transmit and receive
		asynchronous data.
		1	– A clock is input via GPIO pin 20 and is used synchronously to sample receive data
		and drive transmit data.
		Note: Serial port 1’s UART uses GPIO pin 18 for the sample clock input; serial port 2
		does not support the sample clock function. The user must also program the appropriate
		bits in the GPDR and GAFR registers within the system control module.
5	RCE	Receive clock edge select.
		0	– Rising edge of clock input on GPIO pin 20 used to latch data from the receive pin if SCE=1.
		1	– Falling edge of clock input on GPIO pin 20 used to latch data from the receive pin if SCE=1.
6	TCE	Transmit clock edge select.
		0 – Rising edge of clock input on GPIO pin 20 used to drive data onto the transmit pin if SCE=1.
		1	– Falling edge of clock input on GPIO pin 20 used to drive data onto the transmit pin if
		SCE=1.
7	—	Reserved.

SA-1100 Developer’s Manual 11-133