Renesas Hitachi H8S/2191, Hardware Manual

Page: 656 / 1065

Rev. 2.0, 11/00, page 629 of 1037
28.3.4 Register Descriptions
(1) Reference Period Mode Register (RFM)
0
0
1
0
W
2
0
W
3
0
4
0
W
0
W
5 6
0
7
REX CRD OD/EV VST VEG
0
W
RCS
W W W
VNA CVS
Bit :
Initial value :
R/W :
RFM is an 8-bit write-only register which determines the operational state of the reference signal
generators. If a read is attempted, an undetermined value is read out.
It is initialized to H'00 by a reset, stand-by or module stop.
RFM is accessible by byte access only. If accessed by a word, its operation is not assured.
Bit 7: Clock Source Selection Bit (RCS)
Selects the clock source supplied to the counter. (
φ
s = fosc/2)
Bit 7
RCS Description
0
φ
s/2 (Initial value)
1
φ
s/4
Bit 6: Mode Selection Bit (VNA)
Selects whether the transition to free-run operation when the REF30 signals are being generated
in sync with the VD signals in REC mode is controlled automatically by the V noise detection
signal, which has been detected by the sync signal detection circuit, or is controlled manually by
software.
Bit 6
VNA Description
0 Manual mode (Initial value)
1 Auto mode