LAN83C175 Datasheet, PDF (66/92 Pages) SMSC Corporation – Ethernet CARDBUS Integrated Controller With Modem Support

84 - STATUS_m Register
3 and 2 - STS_EVNT: When bit 3 of this
register is 1, it indicates that RDYM has
transitioned from 0 to 1. When bit 2 of this
register is 1, it indicates that RINGIN has
transitioned from 0 to 1. When either of these
signals transition, it is considered a modem
event. If these bits are not masked by
NVCTL_m(1:0), an event will be logged in the
modem present state register bit 1 and the
modem function present state will go to 1. If
these bits are not masked by NVCTL_m(6:5) an
interrupt event will occur, causing an interrupt to
be sent to the host system if STATUSREG_EN,
from the NVCTL_E register, is 1.
1 - RDYM: This register reflects that status of
the RDYM signal driven by the modem. It is not
host writable.
0 - RINGIN: This register reflects that status of
the RINGIN signal driven by the modem. It is
not host writable.
88 - Modem Function Event Register
31 through 16 - Unused
15 - INTR_M: This indicates that the modem
has signaled an interrupt condition.
3 and 2 - BVD: Battery voltage detect is not
used, and a 0 is returned when this register is
read.
1 - STSCHG: When this signal is true, it
indicates that RDYM or RINGIN have
transitioned from 0 to 1. It is reset by writing a 1
to this register location. Note also that
STSCHG_EN, NVCTL_e(12) must be active for
the CSTSCHG pin to be driven active to the
host.
0 - WP: Write protect is not used, and 0 is
returned in this bit location.
8C - Modem Function Mask Register
31 through 16 - Unused
15 - MSK_INTR_M: This is the masking bit for
the modem function event register bit 15.
6 - PWM: Pulse Width Modulation audio
enable. This value is always 0, as this chip
does not support this type of signal.
5 - BAM: Binary Audio Enable, this controls
whether binary audio from the modem will be
passed to the CardBus CAUDIO pin.
3 through 2 - MSK_BVD: This value is always
0.
1 - MSK_STSCHG: This is the masking bit for
the modem function event register bit 15.
0 - MSK_WP: This value is always 0.
90 - Modem Present State Register
31through 16 - Unused
15 - INTR_M: This indicates that the modem
has signaled an interrupt condition.
14 through 4 - Unused
3 and 2 - BVD: Battery voltage detect is not
used, and a 0 is returned when this register is
read.
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