User Manual

5-12 EP7309/11/12 User’s Manual - DS508UM4
Copyright Cirrus Logic, Inc. 2003
System Registers
5
System Flag Register 2 (SYSFLG2)
Address: 0x8000.1140 , Read Only
Definition: The SYSFLG2 system flag register i s a 32-bit read only register. It
provides information regarding the status of th e CPU and associated
peripherals.
Bit Descriptions:
SS2RXOF: Master/slave SSI2 RX FIFO overflow. This bit is s et when a write
is attempted to a full RX FIFO (i.e., when RX is still receiving data
and the FIFO is full). This can be cleared in one of two ways:
1) Em pty the FIFO (rem ove data from F IFO) and then
write to
SRXEOF location.
2) Disable the RX (affects of disabling the RX will not take
place until a full SSI2 clock cycle after it is disabled)
RESVA L: Master/slave SSI2 RX FIFO residual byte present, cleared by
popping the residual byte into the SSI2 RX FIFO or by a new RX
frame sync pulse.
RESFRM: Master/slave SSI2 RX FIFO residual b yte present, cleared only by
anewRXframesyncpulse.
SS2RXFE: Master/slave SSI2 RX FIFO empty bit. This wi ll be set if the
16 x 16 RX FIFO is empty.
SS2TXFF: Master/slave SSI2 TX FIFO full bit. This will be set if the 16 x 16
TX FIFO is full. This will get cleared when data is removed from
the FIFO or the EP73xx is reset.
SS2TXUF: Master/slave SSI2 TX FIFO Underflow bit. This wi ll be set if th ere
is attempt to transmit when TX FIFO is empty. This will be cleared
when FIFO gets loaded with data.
CKMODE: This bit reflects th e status of the
CLKSEL (PE[2])input,latched
during
nPOR. When low, the PLL is running and the chip is
operating in 18.432–73.728 MHz m ode. When high the chip is
operating from a n external 13 MHz clock.
UBUSY2: UART2 transmitter busy. This bit is set while UART2 is busy
transmitting data; it is gua ranteed to remain set until the complete
byte has been sent, including all stop bits.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
RSVD UTXFF2 URXFE2 RSVD
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RSVD UBUSY
2
RSVD CKMOD
E
SS2TXU
F
SS2TXF
F
SS2RXF
E
RESFR
M
RESVAL SS2RX
OF