AP513 ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
- 36 -
http://www.acromag.com
- 36 -
www.acromag.com
These two bits set the trigger level for the transmit FIFO
interrupt. The UART will issue a transmit interrupt when the
number of characters in the FIFO falls below the selected
trigger level, or when it gets empty in case that FIFO did not
get filled over the trigger level on last reload. Refer to Table
3.10 for selections. The FCTR[7:6] are associated with these 2
bits.
7,6
Receive FIFO Trigger Select:
These two bits set the trigger level for the receive FIFO. The
UART will issue a receive interrupt when the number of
characters in the FIFO crosses the trigger level. Refer to Table
3.10 for selections. The FCTR[7:6] are associated with these 2
bits. Note that the receiver and transmitter cannot use
different trigger tables. Whichever selection is made applies
to both the Rx and Tx side.
1
Bits 4 and 5 are only programmable when the EFR bit 4
is set to “1”. A
power-up or system reset sets all FCR bits to 0.
Table 3.14 Transmit and Receive
FIFO Trigger Table and Level
Selection
Trigger
Table
FCTR
[7:6]
FCR
[7:6]
FCR
[5:4]
Rx
Trigger
Level
Tx
Trigger
Level
Compatibility
A
0 0
0 0
0 1
1 0
1 1
0 0
1
4
8
14
1
16C550, 16C2550,
16C2552, 16C554,
16C580, 16L580
B
0 1
0 0
0 1
1 0
1 1
0 0
0 1
1 0
1 1
8
16
24
28
16
8
24
30
16C650A, 16L651
C
1 0
0 0
8
16C654
