NO:
W90P710 Programming Guide
VERSION:
2.0
PAGE:
197
The above information is the exclusive intellectual property of Winbond Electronics and shall not be disclosed, distributed or reproduced without permission
from Winbond.
Table No.: 2005-W90P710-11-A
In principle, the higher the active threshold level is set, the better performance we get. But if big
active threshold level is set, received data characters maybe stored in receiver FIFO for a long time,
because the number of data characters may not reach active threshold level and interrupt can’t be
trigger.
To avoid this circumstance, user can set
BTOIE
and
BTOIC[6~0]
in register
SCHI_BTOR
to
enable receiver buffer timeout interrupt. If
BTOIE
and
ERDRI
(in register
SCHI_IER
) are set, one
internal timer resets and starts counting (the counting unit is ETU) whenever the receiver FIFO
receives a new data word. Once the content of timer is equal to that of time out interrupt comparator
(
BTOIC[6~0]
), a receiver time out interrupt is generated. The interrupt notifies host to read data from
FIFO. A new incoming data word or receiver FIFO empty clear this interrupt.
16.3.4 Parity
Error
management
The error character in reception or in transmission will cause parity error. Bit 4 (
EPE
) in register
SCHI_SCCR
enables even parity check. When
EPE
is set to ‘1’, even parity is required for
transmission and reception. Odd parity is demanded whe
EPE
is set to ‘0’.
The bits 5, 4, 3 (
PEC[2~0]
) in register
SCHI_SCFR
determine the number of allowed repetitions
in reception or in transmission before setting bit 2 (
PBER
) in register
SCHI_SCSR
. The value 000
indicates that, if only one parity error has occurred,
PBER
is set; the value 111 indicate that bit
PBER
will be set after 8 parity errors.
According to different protocol type, there are different process for parity error, the protocol type
is set by bit 3 (
PROT
) in register
SCHI_SCCR
:
In protocol T = 0
- In reception
1. If the programmed number (
PEC[2~0]
) of allowed parity errors is reached, bit
PBER
in register
SCHI_SCSR
will be set as long as register
SCHI_SCSR
has not been read.
2. If a correct character is received before the programmed error number is reached, the error
counter will be reset