SH7269 datasheet(17/26 Pages) RENESAS

17 / 26 page

SH7268/SH7269 Group

Transmission/Reception of Renesas SPDIF Interface

6.8.3

Starting of RSPDIF Transmission

Figure 6.5 shows the Starting of RSPDIF Transmission.

TRCS register

← H'10200000

CHNO bit = 2

: Right channel

io_spdout_start

Write left channel status info. to

data register

return

TUI register

← user information (4-byte)

: String of letters are transferred as user information in the

sample code, but the size in the register will be set by 4-

byte. Reference location is controlled by the

g_spdout.u_idx variable.

Allow transmitter module

DMA transfer

CTRL register

TDE bit ← 1

: Allow transmitter module DMA transfer request

Write first 4 bytes of user info. to

data register

Wait until setting is changed

Allow transmitter user info. interrupt

Allow transfer of

user information

Set DMA transfer of

audio data

io_init_dmac4

io_reload_dmac4

CTRL register

AOS bit ← 0

: User information exists in transmitter user data register

CTRL register

TUII bit ← 1

: Allow transmitter user information register

empty interrupt

TLCS register

← H'10100000

CLAC bit =1

: Clock accuracy level 1

FS bit = 0

: Sampling frequency 44.1kHz

CHNO bit = 1

: Left channel

CATCD bit = 0

: 2-channel general format

CTL bit = 0

: 2-channel audio, pre-emphasis prohibition,

copy prohibition, LPCM

STAT register

Wait until TUIR bit and CSTX bit are cleared to zero

DMA transfer of audio data needs to be transferred by rotation

between the channel 1 and channel 2. Transmit data of transfer

source address shall be prepared accordingly.

Allow operation of

transmitter module

CTRL register

TME bit ← 1

: Allow operation of RSPDIF transmission

(should be done before writing data)

Write right channel status info. to

data register

Prohibit interrupt that generates

request when operation of

transmitter module is allowed

CTRL register

TUII bit ← 0

: Prohibit transmitter user information register

empty interrupt

TCSI bit ← 0

: Prohibit transmitter channel status register

empty interrupt

TCBI bit ← 0

: Prohibit transmitter channel buffer interrupt

Set of

channel

status info.

Setting of

user info.

Setting of

audio data

[Note] Writing to the register must be done in following order.

(1) channel status information, (2) user information, (3) audio data infromation

Figure 6.5 Starting of RSPDIF Transmission

R01AN1188EJ0100 Rev.1.00

Page 17 of 23

Jul. 27, 2012

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