SH7764 Datasheet, PDF (728/1752 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 18 Serial Sound Interface (SSI)
Initial
Bit
Bit Name 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 the UIEN
bit. In order to clear it to 0, write 0 to it.
If UIRQ = 1 and UIEN = 1, then an interrupt will be
generated.
• TRMD = 0 (Receive mode)
If UIRQ = 1, it indicates that SSIRDR0 to SSIRDR5
were 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 may cause destruction of
multi-channel data.
• TRMD = 1 (Transmit mode)
If UIRQ = 1, it indicates that the transmitted data
was not written in SSITDR0 to SSITDR5. 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 receive mode.
Note: When underflow error occurs, the data in the
data buffer will be transmitted until the next
data is written in.
Rev. 1.00 Nov. 22, 2007 Page 672 of 1692
REJ09B0360-0100