SH7261 datasheet(814/1348 Pages) RENESAS

814 / 1348 page

Section 18 Serial Sound Interface (SSI)

Rev. 2.00 Sep. 07, 2007 Page 782 of 1312

REJ09B0320-0200

Bit

Bit Name

Initial

Value

R/W

Description

31 to 29



All 0

Reserved

The read value is not guaranteed. The write value

should always be 0.

DMRQ

DMA Request Status Flag

This status flag allows the CPU to recognize the value

of the DMA request pin on the SSI module.

• TRMD = 0 (Receive mode)

If DMRQ = 1, the SSIRDR has unread data.

If SSIRDR is read, DMRQ = 0 until there is new

unread data.

• TRMD = 1 (Transmit mode)

If DMRQ = 1, SSITDR requires data to be written to

continue the transmission to the audio serial bus.

Once data is written to SSITDR, DMRQ = 0 until it

requires further transmit data.

UIRQ

R/W*

Underflow Error Interrupt Status Flag

This status flag indicates that data was supplied at a

lower rate than was required.

In either case, this bit is set to 1 regardless of the value

of the UIEN bit and can be cleared by writing 0 to this

bit.

If UIRQ = 1 and UIEN = 1, an interrupt occurs.

• TRMD = 0 (Receive mode)

If UIRQ = 1, SSIRDR was read before there was

new unread data indicated by the DMRQ or DIRQ

bit. This can lead to the same received sample

being stored twice by the host leading to potential

corruption of multi-channel data.

• TRMD = 1 (Transmit mode)

If UIRQ = 1, SSITDR did not have data written to it

before it was required for transmission. This will

lead to the same sample being transmitted once

more and a potential corruption of multi-channel

data. This is more serious error than a receive

mode underflow as the output SSI data results in

error.

Note: When underflow error occurs, the current data in

the data buffer of this module is transmitted until

the next data is filled.

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