sc68c2550b NXP Semiconductors, sc68c2550b Datasheet - Page 10

• Manufacturer Part Number: sc68c2550b
• Description: Sc68c2550b 5 V, 3.3 V And 2.5 V Dual Uart, 5 Mbit/s Max. , With 16-byte Fifos And Motorola Up Interface
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14941
Product data sheet
6.6 DMA operation
Table 6:
The SC68C2550B FIFO trigger level provides additional flexibility to the user for block
mode operation. LSR[6:5] provide an indication when the transmitter is empty or has an
empty location(s). The user can optionally operate the transmit and receive FIFOs in the
DMA mode (FCR[3]). When the transmit and receive FIFOs are enabled and the DMA
mode is de-activated (DMA Mode 0), the SC68C2550B activates the interrupt output pin
for each data transmit or receive operation. When DMA mode is activated (DMA Mode 1),
the user takes the advantage of block mode operation by loading or unloading the FIFO in
a block sequence determined by the receive trigger level and the transmit FIFO. In this
mode, the SC68C2550B sets the TXRDY (or RXRDY) output pin when characters in the
transmit FIFO is below 16, or the characters in the receive FIFOs are above the receive
trigger level.
Output
baud rate
50
75
110
150
300
600
1200
2400
3600
4800
7200
9600
19.2 k
38.4 k
57.6 k
115.2 k
Fig 3. Crystal oscillator connection
Baud rate generator programming table using a 1.8432 MHz clock
Output
16 clock divisor
(decimal)
2304
1536
1047
768
384
192
96
48
32
24
16
12
6
3
2
1
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 16-byte FIFOs
Rev. 02 — 28 April 2005
Output
16 clock divisor
(HEX)
900
600
417
300
180
C0
60
30
20
18
10
0C
06
03
02
01
XTAL1
1.8432 MHz
C1
22 pF
X1
XTAL2
002aab325
C2
33 pF
DLM
program value
(HEX)
09
06
04
03
01
00
00
00
00
00
00
00
00
00
00
00
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
SC68C2550B
DLL
program value
(HEX)
00
00
17
00
80
C0
60
30
20
18
10
0C
06
03
02
01
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