TL16PC564BLVI_16 Datasheet, PDF (10/35 Pages) Texas Instruments – PCMCIA UNIVERSAL ASYNCHRONOUS RECEIVER TRANSMITTER

TL16PC564BLVI
Not Recommended For New Designs
PCMCIA UNIVERSAL ASYNCHRONOUS RECEIVER TRANSMITTER
SLLS627− SEPTEMBER 2004
that the subsystem has written data to attribute memory provided bit 2 of the subsystem control register
(STSCHG enable) is high. The host CPU can clear STSCHG by reading any location in attribute memory. The
control of these signals is synchronized to ARBCLKO to ensure there are no false assertions/deassertions.
There is additional arbitration performed for instances of simultaneous assertion/deasseration of IRQ or
STSCHG. When a subsystem write and host CPU read occurs simultaneously, STSCHG may be briefly
deasserted prior to being asserted, but the write ultimately wins arbitration. When the host CPU read occurs
more than one-half an arbitration clock after the subsystem write, STSCHG is deasserted. IRQ is arbitrated in
a similar fashion.
host CPU/UART interface
The UART select is derived from either host CPU address information or logic levels on CE1, CE2 and REG.
In the address mode, host CPU address bits HA9, HA7, HA6, HA5, and HA3 are combined with conditional
derivatives of HA4 and HA8 to select the UART (HA4 and HA8 select COM ports 1−4 based on settings in the
subsystem control register). CE1 and CE2 are combined such that either of these two signals in combination
with REG enable the UART in the event that these signals are present. In the event that CE1 or CE2 are not
present, the UART must be accessed in the address mode previously described. The UART select in
conjunction with IORD and IOWR allows host CPU accesses to the UART. Host CPU address bits HA2−HA0
are decoded to select which UART register is to be accessed.
All UART registers remain intact with the exception of the FIFO control register (FCR) and the modem-control
register (MCR). The FCR (host CPU write-only address 2) bits 4 and 5 in conjunction with EXTEND control RTS
operation and FIFO depth as follows:
BIT 5
X
0
0
1
1
BIT 4
X
0
1
0
1
EXTEND
H
L
L
L
L
RTS OPERATION
Normal
Normal
Auto
Normal
Auto
FIFO DEPTH
16 bytes
16 bytes
16 bytes
64 bytes
64 bytes
FCR bit 5 high and EXTEND low redefine the receiver FIFO trigger levels set by FCR bits 6 and 7 as follows:
BIT 7
0
0
1
1
BIT 6
0
1
0
1
TRIGGER LEVEL
1
16
32
56
The MCR (host CPU address 4) bit 5 is read only. Bit 5 is controlled by the subsystem to enable (high) the
auto-CTS mode of operation
subsystem/UART interface
The UART provides a serial-communications channel to the subsystem with enhanced RTS control (see
auto-RTS description). This channel is capable of operating at 115 kbps and is the main communications
channel to the subsystem (refer to the TL16C550 specification for the detailed description of the
serial-communications channel).
Many of the UART registers have been mapped into the subsystems memory space as read only. In addition,
MCR bit 5 (subsystem address 130 hex) is controlled by the subsystem to enable (high) auto-CTS. The
subsystem can read the MCR at address 134 hex. When reading the FCR (subsystem address 132 hex), bits
1 and 2 are always high, and bits 4 and 5 are low only when EXTEND is low and the host CPU has set them
high (64-byte FIFOs and auto-RTS enabled) (refer to the subsystem memory map).
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