OM13005,598 NXP Semiconductors, OM13005,598 Datasheet - Page 87

• Manufacturer Part Number: OM13005,598
• Description: BOARD EVAL EM773 METER US PLUG
• Manufacturer: NXP Semiconductors
• Type: Other Power Managementr

Specifications of OM13005,598

• Design Resources: Plug Meter Schematics, Gerber Files USB Dongle Schematics, Gerber Files
• Main Purpose: Power Management, Energy/Power Meter
• Embedded: Yes, MCU, 32-Bit
• Utilized Ic / Part: EM773FHN33,551
• Interface Type: USB
• Maximum Operating Temperature: + 150 C
• Operating Supply Voltage: 1.8 V to 3.6 V
• Product: Power Management Development Tools
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Primary Attributes: -
• Secondary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: EM773, OL2381
• Other names: 568-6680

NXP Semiconductors
UM10415
User manual
9.6.14 Auto-baud modes
The U0ACR AutoRestart bit can be used to automatically restart baud rate measurement
if a time-out occurs (the rate measurement counter overflows). If this bit is set, the rate
measurement will restart at the next falling edge of the UART Rx pin.
The auto-baud function can generate two interrupts.
The auto-baud interrupts have to be cleared by setting the corresponding U0ACR
ABTOIntClr and ABEOIntEn bits.
The fractional baud rate generator must be disabled (DIVADDVAL = 0) during auto-baud.
Also, when auto-baud is used, any write to U0DLM and U0DLL registers should be done
before U0ACR register write. The minimum and the maximum baud rates supported by
UART are function of UART_PCLK, number of data bits, stop bits and parity bits.
When the software is expecting an ”AT" command, it configures the UART with the
expected character format and sets the U0ACR Start bit. The initial values in the divisor
latches U0DLM and U0DLM don‘t care. Because of the ”A" or ”a" ASCII coding
(”A" = 0x41, ”a" = 0x61), the UART Rx pin sensed start bit and the LSB of the expected
character are delimited by two falling edges. When the U0ACR Start bit is set, the
auto-baud protocol will execute the following phases:
1. On U0ACR Start bit setting, the baud rate measurement counter is reset and the
2. A falling edge on UART 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, the rate counter will stop on next falling edge of the UART Rx pin. If
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ratemin
The U0IIR ABTOInt interrupt will get set if the interrupt is enabled (U0IER ABToIntEn
is set and the auto-baud rate measurement counter overflows).
The U0IIR ABEOInt interrupt will get set if the interrupt is enabled (U0IER ABEOIntEn
is set and the auto-baud has completed successfully).
UART U0RSR is reset. The U0RSR baud rate is switched to the highest rate.
measuring counter will start counting UART_PCLK cycles.
the frequency of the UART input clock, guaranteeing the start bit is stored in the
U0RSR.
counter will continue incrementing with the pre-scaled UART input clock
(UART_PCLK).
Mode = 1, the rate counter will stop on the next rising edge of the UART Rx pin.
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All information provided in this document is subject to legal disclaimers.
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Rev. 1 — 10 September 2010
Chapter 9: EM773 Universal Asynchronous Transmitter (UART)
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UART baudrate
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PCLK
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paritybits
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stopbits
UM10415
© NXP B.V. 2010. All rights reserved.
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