OM11077 NXP Semiconductors, OM11077 Datasheet - Page 455

• Manufacturer Part Number: OM11077
• Description: MODULE DIMM LPC2478 ARM7
• Manufacturer: NXP Semiconductors

Specifications of OM11077

• Accessory Type: Module Card
• For Use With/related Products: ARM-57TS-LPC2478
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 568-4742

NXP Semiconductors
UM10237_4
User manual
Fig 69. Auto-CTS Functional Timing
UART1 TX
CTS1 pin
4.10 Auto-CTS
start
bits0..7
The Auto-CTS function is enabled by setting the CTSen bit. If Auto-CTS is enabled the
transmitter circuitry in the U1TSR module checks CTS1 input before sending the next data
byte. When CTS1 is active (low), the transmitter sends the next byte. To stop the
transmitter from sending the following byte, CTS1 must be released before the middle of
the last stop bit that is currently being sent. In Auto-CTS mode a change of the CTS1
signal does not trigger a modem status interrupt unless the CTS Interrupt Enable bit is set,
Delta CTS bit in the U1MSR will be set though.
generating a Modem Status interrupt.
Table 407. Modem status interrupt generation
The auto-CTS function reduces interrupts to the host system. When flow control is
enabled, a CTS1 state change does not trigger host interrupts because the device
automatically controls its own transmitter. Without Auto-CTS, the transmitter sends any
data present in the transmit FIFO and a receiver overrun error can result.
illustrates the Auto-CTS functional timing.
While starting transmission of the initial character the CTS1 signal is asserted.
Transmission will stall as soon as the pending transmission has completed. The UART will
continue transmitting a 1 bit as long as CTS1 is deasserted (high). As soon as CTS1 gets
deasserted transmission resumes and a start bit is sent followed by the data bits of the
next character.
Enable
Modem
Status
Interrupt
(U1ER[3]
)
0
1
1
1
1
1
1
1
1
stop
CTSen
(U1MCR[7])
x
0
0
0
1
1
1
1
1
Rev. 04 — 26 August 2009
CTS
Interrupt
Enable
(U1IER[7])
x
x
x
x
0
0
1
1
1
start
bits0..7
Delta CTS
(U1MSR[0])
x
0
1
x
x
x
0
1
x
stop
Table 17–407
Delta DCD or Trailing Edge
RI or
Delta DSR (U1MSR[3] or
U1MSR[2] or U1MSR[1])
x
0
x
1
0
1
0
x
1
Chapter 17: LPC24XX UART1
lists the conditions for
start
UM10237
© NXP B.V. 2009. All rights reserved.
Figure 17–69
bits0..7
Modem
Status
Interrupt
No
No
Yes
Yes
No
Yes
No
Yes
Yes
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