
Fast AMBA Peripherals
12-20
GMS30C7201 Data Sheet
buffer and serial output shifter is cleared. Clearing TXE to zero ensures the transmitter
is disabled. Note that TXE is ignored by the SIr (which is always enabled whenever
selected by the IrEnable register).
Also note that even though the IrDA standard only permits half-duplex operation, this
implementation does not restrict the user from transmitting and receiving data at the
same time; both are fully independent units. This function is particularly useful when
using loop back mode, described above.
Receive Enable (RXE)
The receive enable (RXE) bit is used to enable or disable MIr/FIr receive operation.
When RXE=0, the receive logic is disabled and its clocks are turned off to conserve
power. When RXE=1, the receiver logic is enabled for IrDA reception. It is required that
the user first program all other control bits before setting RXE. If the RXE bit is cleared
to zero while the Ir interface is actively receiving data, reception is stopped immediately,
all data within the receive buffer and serial input shifter is cleared. Clearing RXE to zero
ensures the selected Ir receiver is disabled. Note that RXE is ignored by the SIr (which
is always enabled whenever selected by the IrEnable register).
Also note that even though the IrDA standard only permits half-duplex operation, the
FIr does not restrict the user from transmitting and receiving data at the same time; both
are fully independent units. This function is particularly useful when using the FIr in loop
back mode.
Receive buffer Interrupt Mask (RIM)
The receive buffer interrupt mask (RIM) bit is used to mask or enable the receive buffer
service request interrupt. When RIM=0, the interrupt is masked, and the state of the
receive buffer service request (RFS) bit within MIr/FIr status register 0 is ignored by the
interrupt controller. When RIM=1, the interrupt is enabled, and whenever RFS is set
(one) an interrupt request is made to the interrupt controller. Note that programming
RIM=0 does not affect the current state of RFS or the receive buffer logic
’
s ability to set
and clear RFS, it only blocks the generation of the interrupt request.
Also note that RIM does not affect generation of the receive buffer DMA request which
is asserted whenever both RFS is set and the receiver buffer error/end flag (EIF) is
clear.
Transmit buffer Interrupt Mask (TIM)
The transmit buffer interrupt mask (TIM) bit is used to mask or enable the transmit
buffer service request interrupt. When TIM=0, the interrupt is masked and the state of
the transmit buffer service request (TFS) bit within MIr/FIr status register 0 is ignored
by the interrupt controller. When TIM=1, the interrupt is enabled, and whenever TFS is
set (one) an interrupt request is made to the interrupt controller. Note that programming
TIM=0 does not affect the current state of TFS or the transmit buffer logic
’
s ability to set
and clear TFS, it only blocks the generation of the interrupt request.
TIM does not affect generation of the transmit buffer DMA request which is asserted
whenever TFS is set.
Address Match Enable (AME)
The address match enable (AME) bit is used to enable or disable the receive logic from
comparing the address programmed in the address match value (AMV) bit-field, to the
address of all incoming frames. When AME is set (equals one), data is stored in the
receive buffer only for those frames which have addresses that match AMV, and for any
frame which contains the broadcast address (0hFF). For frames in which the address