AMD Am188TMER, Am186TMER user manual Parity Mode Bit Settings, Asynchronous Serial Port 11-3

Bits 6–5: Parity Mode (PMODE) —This field specifies how parity generation and checking are performed during transmission and reception, as shown in Table 11-2.

Table 11-2 Parity Mode Bit Settings

Parity	PMODE
None (No parity bit in frame)	0 X
Odd (Odd number of 1s in frame)	1 0
Even (Even number of 1s in frame)	1 1

If parity checking and generation is selected, a parity bit is received or sent in addition to the specified number of data bits.

The value of PMODE after power-on reset is 00b.

Bit 4: Word Length (WLGN)—This bit determines the number of bits transmitted or received in a frame. If WLGN is 0, the serial port sends and receives 7 bits of data per frame. If WLGN is 1, the serial port sends and receives 8 bits of data per frame. The value of WLGN after power-on reset is 0.

Bit 3: Stop Bits (STP)—A 0 in the STP bit specifies that one stop bit is used to signify the end of a frame. A 1 in this bit specifies that two stop bits are used to signify the end of a frame. The value of STP after power-on reset is 0.

Bit 2: Transmit Mode (TMODE)—The TMODE bit enables data transmission and controls the operational mode of the serial port for the transmission of data. If TMODE is 0, the transmit section and transmit interrupts of the serial port are disabled. If TMODE is 1, the transmit section of the serial port is enabled. The value of TMODE after power-on reset is 0.

Bit 1: Receive Status Interrupt Enable (RSIE)—This bit enables the serial port to generate an interrupt because of an exception during reception. If this bit is 1 and the serial port receives a break, or experiences a framing error, parity error, or overrun error, the serial port generates a serial port interrupt. The value of RSIE after power-on reset is 0.

Bit 0: Receive Mode (RMODE)—This field enables data reception and controls the operational mode of the serial port for the reception of data. If RMODE is 0, the receive section and receive interrupts of the serial port are disabled. If RMODE is 1, the receive section of the serial port is enabled. The value of RMODE after power-on reset is 0.

Note: The asynchronous serial interface pins TXD and RXD are multiplexed with programmable I/O pins. To enable the pins to function as asynchronous serial interface, the PIO mode and PIO direction settings for the TXD and RXD pins must be set to 0 for normal operation. For more information, see Chapter 13, “Programmable I/O Pins.”

Asynchronous Serial Port 11-3