SH7760 Datasheet, PDF (957/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

25.5.7 Power-Down Mode
It is possible to stop the supply of clock to the HAC using the CSTP15 and CSTP16 bits in
CLKSTP00, which is a register used in power-down modes.
To cancel module standby mode and resume the supply of clock to the HAC, write 1 to the
corresponding bits in CLKSTPCLR00. It enables all accesses to the HAC.
To place the HAC into the power-down mode, take the following steps:
1. Check that all data transfers have ended. Also check that the transmit buffer is empty and the
receive buffer has been read out to be empty.
2. Disable all DMA requests and interrupt requests.
3. Place the codec into power-down mode.
4. Write 1 to the CSTP15 and CSTP16 bits in CLKSTP00.
25.5.8 Notes
The HAC_SYNC signal is generated by the HAC to indicate the position of slot 0 within a frame.
When using two channels of the HAC simultaneously, connect the HAC_RES pin to the reset pins
on both of the connected codecs.
25.5.9 Reference
AC'97 Component Specification, Revision 2.1
Rev. 1.0, 02/03, page 907 of 1294