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參數(shù)資料
| 型號： | SCN68681C1N40 |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | Dual asynchronous receiver/transmitter DUART |
| 中文描述： | 2 CHANNEL(S), 1M bps, SERIAL COMM CONTROLLER, PDIP40 |
| 文件頁數(shù)： | 24/28頁 |
| 文件大?。?/td> | 187K |
| 代理商： | SCN68681C1N40 |
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Philips Semiconductors
Product specification
SCN68681
Dual asynchronous receiver/transmitter (DUART)
1998 Sep 04
24
16x mode or one bit time in the 1x mode. Also, if the transmitter,
while in the enabled state and underrun condition, is immediately
disabled after a single character is loaded to the transmit holding
register, that character will not be sent.
In general, when it is desired to disable the transmitter before the
last character is sent AND the TxEMT bit is set in the status register
(TxEMT is always set if the transmitter has underrun or has just
been enabled), be sure the TxRDY bit is active immediately before
issuing the transmitter disable instruction. TxRDY sets at the end of
the “start bit” time. It is during the start bit that the data in the
transmit holding register is transferred to the transmit shift register.
Non-standard baud rates are available as shown in Table 6 below,
via the BRG Test function.
Table 6.
Baud Rates Extended
Normal BRG
BRG Test
CSR[7:4]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
ACR[7] = 0
50
110
134.5
200
300
600
1,200
1,050
2,400
4,800
7,200
9,600
38.4K
Timer
I/O2 – 16X
I/O2 – 1X
ACR[7] = 1
75
110
134.5
150
300
600
1,200
2,000
2,400
4,800
1,800
9,600
19.2K
Timer
I/O2 – 16X
I/O2 – 1X
ACR[7] = 0
4,800
880
1,076
19.2K
28.8K
57.6K
115.2K
1,050
57.6K
4,800
57.6K
9,600
38.4K
Timer
I/O2 – 16X
I/O2 – 1X
ACR[7] = 1
7,200
880
1,076
14.4K
28.8K
57.6K
115.2K
2,000
57.6K
4,800
14.4K
9,600
19.2K
Timer
I/O2 – 16X
I/O2 – 1X
NOTE:
Each read on address H‘2’ will toggle the baud rate test mode. When in the BRG test mode, the baud rates change as shown to the left. This
change affects all receivers and transmitters on the DUART. See “Extended baud rates for SCN2681, SCN68681, SCC2691, SCC2692,
SCC68681 and SCC2698B”in application notes elsewhere in this publication.
The test mode at address H‘A’ changes all transmitters and receivers to the 1x mode and connects the output ports to some internal nodes.
A condition that occurs infrequently has been observed where the receiver will ignore all data. It is caused by a corruption of the start bit
generally due to noise. When this occurs the receiver will appear to be asleep or locked up. The receiver must be reset for the UART to
continue to function properly.
Reset in the Normal Mode (Receiver Enabled)
Recovery can be accomplished easily by issuing a receiver software reset followed by a receiver enable. All receiver data, status and
programming will be preserved and available before reset. The reset will NOT affect the programming.
Reset in the Wake-Up Mode (MR1[4:3] = 11)
Recovery can also be accomplished easily by first exiting the wake-up mode (MR1[4:3] = 00 or 01 or 10), then issuing a receiver software
reset followed by a wake-up re-entry (MR1[4:3] = 11). All receiver data, status and programming will be preserved and available before
reset. The reset will NOT affect the programming.
The receiver has a digital filter designed to reject “noisy” data transitions and the receiver state machine was designed to reject noisy start
bits or noise that might be considered a start bit. In spite of these precautions, corruption of the start bit can occur in 15ns window
approximately 100ns prior to the rising edge of the data clock. The probability of this occurring is less than 10
–5
at 9600 baud.
A corrupted start bit may have some deleterious effects in ASYNC operation if it occurs within a normal data block. The receiver will tend
to align its data clock to the next ‘0’ bit in the data stream, thus potentially corrupting the remainder of the data block. A good design
practice, in environments where start bit corruption is possible, is to monitor data quality (framing error, parity error, break change and
received break) and “data stopped” time out periods. Time out periods can be enabled using the counter/timer in the SCC2691, SCC2692,
SCC2698B and SC68692 products. This monitoring can indicate a potential start bit corruption problem.
SD00097
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SCN68681E1A44 | Dual asynchronous receiver/transmitter DUART |
| SCN68681 | Dual universal asynchronous receiver/transmitter (DUART）(雙通用異步接收器/傳送器) |
| SCN68681E1F40 | Dual asynchronous receiver/transmitter DUART |
| SCN68681E1N40 | Dual asynchronous receiver/transmitter DUART |
| SCN68681C1A44 | RES 16K OHM 1/16W 0.1% 0402 SMD |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SCN68681E1A44 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Dual asynchronous receiver/transmitter DUART |
| SCN68681E1F40 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Dual asynchronous receiver/transmitter DUART |
| SCN68681E1N40 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Dual asynchronous receiver/transmitter DUART |
| SCN-800 | 制造商:MEANWELL 制造商全稱:Mean Well Enterprises Co., Ltd. 功能描述:800W Single Output With Parallel Function |
| SCN-800-12 | 制造商:ASTRODYNE 制造商全稱:Astrodyne Corporation 功能描述:800W With Parallel Function |
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