RCVDL56DPFL/SP, RCV56DPFL/SP, and RCV336DPFL/SP Designer’s Guide
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Receiver FIFO (RXFIFO)
The 16-byte RXFIFO is always enabled.
The 128-byte RXFIFO Extension (RXFIFOX) is controlled by writing to the Receive FIFO Extension Enable bit (701h:0)
[0 = RXFIFOX disabled; 1 = RXFIFOX enabled (default)].
The lower 16-byte portion of the RXFIFO can be controlled by writing to address 32C. The default value is CBh which gives
a trigger level of 14 bytes and a time-out of 17 clock cycles.
Bits 7-6
Trigger Level. Selects the trigger level in the 16-byte RXFIFO. For example, setting bits 7 and 6 to 1 selects
a trigger level of 14 bytes. That is, RDBF will not become asserted until the receive FIFO is 14 bytes full and
the time-out delay has not elapsed (see below). Both RDBF and RXFNE will remain set until the RXFIFO is
empty.
Bit 7
Bit 6
Trigger Level (No. of Bytes)
0
0
Trigger level = 1
0
1
Trigger level = 4
1
0
Trigger level = 8
1
1
Trigger level = 14
Bit 5
Must be 0.
Bits 4-2
Time-out Delay. Selects the length of idle time that will cause RDBF to be asserted when the RXFIFO is not
empty. Idle time is the length of time that elapses without the MDP writing into the RXFIFO or the host
reading data from the RXFIFO. This feature prevents data from being “held up” in the RXFIFO.
B4
B3
B2
Idle Time (In Bit Times)
0
0
0
9 bit times
0
0
1
13 bit times
0
1
0
17 bit times
0
1
1
21 bit times
1
0
0
25 bit times
1
0
1
29 bit times
1
1
0
33 bit times
1
1
1
37 bit times
Bit 1
Idle Time Time-out Enable. 1 = the time-out enabled; 0 = time out disabled. When Time out is disabled (0),
RDBF will be asserted only when the RXFIFO threshold is reached.
Bit 0
Not Used.
Summary of Contents for RC336DPFL
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