OM11077 NXP Semiconductors, OM11077 Datasheet - Page 460

• 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
4.16 Auto-baud modes
When the software is expecting an ”AT" command, it configures the UART1 with the
expected character format and sets the U1ACR Start bit. The initial values in the divisor
latches U1DLM and U1DLM don‘t care. Because of the ”A" or ”a" ASCII coding
(”A" = 0x41, ”a" = 0x61), the UART1 Rx pin sensed start bit and the LSB of the expected
character are delimited by two falling edges. When the U1ACR Start bit is set, the
auto-baud protocol will execute the following phases:
1. On U1ACR Start bit setting, the baud-rate measurement counter is reset and the
2. A falling edge on UART1 Rx pin triggers the beginning of the start bit. The rate
3. During the receipt of the start bit, 16 pulses are generated on the RSR baud input with
4. During the receipt of the start bit (and the character LSB for mode = 0) the rate
5. If Mode = 0 then the rate counter will stop on next falling edge of the UART1 Rx pin. If
6. The rate counter is loaded into U1DLM/U1DLL and the baud-rate will be switched to
ratemin
UART1 U1RSR is reset. The U1RSR baud rate is switch to the highest rate.
measuring counter will start counting pclk cycles.
the frequency of the UART1 input clock, guaranteeing the start bit is stored in the
U1RSR.
counter will continue incrementing with the pre-scaled UART1 input clock (pclk).
normal operation. After setting the U1DLM/U1DLL the end of auto-baud interrupt
U1IIR ABEOInt will be set, if enabled. The U1RSR will now continue receiving the
remaining bits of the ”A/a" character.
Mode = 1 then the rate counter will stop on the next rising edge of the UART1 Rx pin.
=
2 P
------------------------ -
16 2 15
× CLK
×
Rev. 04 — 26 August 2009
≤
UART
1
baudrate
≤
----------------------------------------------------------------------------------------------------------- -
16
×
(
2
+
databits
PCLK
+
Chapter 17: LPC24XX UART1
paritybits
+
UM10237
stopbits
© NXP B.V. 2009. All rights reserved.
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ratemax