OM13005,598 NXP Semiconductors, OM13005,598 Datasheet - Page 94

• 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
RS-485/EIA-485 Normal Multidrop Mode (NMM)
Setting the RS485CTRL bit 0 enables this mode. In this mode, an address is detected
when a received byte causes the UART to set the parity error and generate an interrupt.
If the receiver is disabled (RS485CTRL bit 1 = ‘1’), any received data bytes will be ignored
and will not be stored in the RXFIFO. When an address byte is detected (parity bit = ‘1’) it
will be placed into the RXFIFO and an Rx Data Ready Interrupt will be generated. The
processor can then read the address byte and decide whether or not to enable the
receiver to accept the following data.
While the receiver is enabled (RS485CTRL bit 1 =’0’), all received bytes will be accepted
and stored in the RXFIFO regardless of whether they are data or address. When an
address character is received a parity error interrupt will be generated and the processor
can decide whether or not to disable the receiver.
RS-485/EIA-485 Auto Address Detection (AAD) mode
When both RS485CTRL register bits 0 (9-bit mode enable) and 2 (AAD mode enable) are
set, the UART is in auto address detect mode.
In this mode, the receiver will compare any address byte received (parity = ‘1’) to the 8-bit
value programmed into the RS485ADRMATCH register.
If the receiver is disabled (RS485CTRL bit 1 = ‘1’), any received byte will be discarded if it
is either a data byte OR an address byte which fails to match the RS485ADRMATCH
value.
When a matching address character is detected it will be pushed onto the RXFIFO along
with the parity bit, and the receiver will be automatically enabled (RS485CTRL bit 1 will be
cleared by hardware). The receiver will also generate an Rx Data Ready Interrupt.
While the receiver is enabled (RS485CTRL bit 1 = ‘0’), all bytes received will be accepted
and stored in the RXFIFO until an address byte which does not match the
RS485ADRMATCH value is received. When this occurs, the receiver will be automatically
disabled in hardware (RS485CTRL bit 1 will be set), The received non-matching address
character will not be stored in the RXFIFO.
RS-485/EIA-485 Auto Direction Control
RS485/EIA-485 mode includes the option of allowing the transmitter to automatically
control the state of the DIR pin as a direction control output signal.
Setting RS485CTRL bit 4 = ‘1’ enables this feature.
Direction control, if enabled, will use the RTS pin when RS485CTRL bit 3 = ‘0’. It will use
the DTR pin when RS485CTRL bit 3 = ‘1’.
When Auto Direction Control is enabled, the selected pin will be asserted (driven LOW)
when the CPU writes data into the TXFIFO. The pin will be de-asserted (driven HIGH)
once the last bit of data has been transmitted. See bits 4 and 5 in the RS485CTRL
register.
The RS485CTRL bit 4 takes precedence over all other mechanisms controlling the
direction control pin with the exception of loopback mode.
RS485/EIA-485 driver delay time
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 10 September 2010
Chapter 9: EM773 Universal Asynchronous Transmitter (UART)
UM10415
© NXP B.V. 2010. All rights reserved.
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