PC87591L datasheet(161/437 Pages) NSC

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Embedded Controller Modules (Continued)

Revision 1.07

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Status Register (USTAT)

This byte-wide, read-only register contains the receive and transmit status bits. The register is cleared (0016) on reset.

Location: 00 FD2616

Type: RO

Bit

76543210

Name

Reserved

XMIP

RB9

BKD

ERR

DOE

Reset

00000000

Bit

Description

PE. The bit is set when a parity error is detected within a received character. The bit is cleared by the hardware

when USTAT register is read.

0: No parity error detected

1: Parity error detected in a received byte since the last time USTAT was read

FE. The bit is set when the USART fails to receive a valid stop bit at the end of a frame. Automatically cleared

on read of USTAT.

0: No framing error detected

1: Framing error detected on a received byte since the last time USTAT was read

DOE. The bit is set when a new character is received and transferred to RBUF before the software has read the

previous character. Automatically cleared on read of the USTAT.

0: No data overrun error detected

1: Data overrun error detected since the last time USTAT was read

ERR. The bit is set any time DOE, FE or PE is set. Automatically cleared if DOE, FE and PE are all zero. This

bit is read only. Any attempt to write to the bit by software does not alter its present value.

0: No DOE, FE or PE has occurred since the last time USTAT register was read.

1: A DOE, FE or PE error has occurred since the last time USTAT register was read.

BKD. If set, indicates that a line break condition has occurred. A break condition is detected if RXD remains low

for a least ten bit times after a missing stop bit has been detected at the end of a frame. The bit is cleared under

the following conditions:

–

On a read of USTAT register, if the break condition on RXD is no longer present. If RXD is still low when USTAT

–

If the read of USTAT register did not cause the bit to be cleared because the break condition on RXD was still

in effect, the hardware clears the bit as soon as the break condition no longer exists, i.e., RXD returns to a high

level.

RB9. Contains the ninth data bit of the last frame received when operating with the 9-bit data format.

0: “0” received in ninth bit position

1: “1” received in ninth bit position

XMIP. Indicates that the USART is transmitting data. It is reset by hardware at the end of the last frame bit.

0: USART is not transmitting

1: USART is transmitting

Reserved.

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