Renesas SH7781 - Manual (Page 1339)

26. Serial Sound Interface (SSI) Module
Rev.1.00 Jan. 10, 2008 Page 1309 of 1658
REJ09B0261-0100
Bit Bit Name
Initial
Value R/W Description
27 UIRQ 0 R/W* Underflow Error Interrupt Status Flag
This status flag indicates that the data has been
supplied at a lower rate than the required rate.
This bit is set to 1 regardless of the setting of UIEN bit.
In order to clear it to 0, write 0 in it.
If UIRQ = 1 and UIEN = 1, then an interrupt will be
generated.
When TRMD = 0 (Receive Mode):
If UIRQ = 1, it indicates that SSIRDR was read out
before DMRQ and DIRQ bits would indicate the
existence of new unread data. In this instance, the
same received data may be stored twice by the host,
which can lead to destruction of multi-channel data.
When TRMD = 1 (Transmit Mode):
If UIRQ = 1, it indicates that the transmitted data was
not written in SSITDR. By this, the same data may be
transmitted one time too often, which can lead to
destruction of multi-channel data. Consequently,
erroneous SSI data will be output, which makes this
error more serious than underflow in the receive mode.
Note: When underflow error occurs, the data in the data
buffer will be transmitted until the next data is
written in.