ade7169f16 Analog Devices, Inc., ade7169f16 Datasheet - Page 120

• Manufacturer Part Number: ade7169f16
• Description: Single-phase Energy Measurement Ic With 8052 Mcu, Rtc And Lcd Driver
• Manufacturer: Analog Devices, Inc.

ADE7169F16
multiprocessor network such as RS-485, the 9
indicate that the frame contains the address of the device that
the master would like to communicate with. The devices on the
network are always listening for a packet with the 9
are configured such that if the 9
be valid and a receive interrupt will not be generated. If the 9
bit is set, all of the devices on the network will receive the
address and get a receive character interrupt. The devices will
examine the address and if it matches a device’s preprogrammed
address, the device will configure itself to listen to all incoming
frames, even those with the 9
initiated communication with that device, all the following
packets with the 9
addressed device until another packet with the 9
received. If the address does not match, the device will continue
listening for address packets.
To transmit, the 8 data bits must be written into SBUF. The
ninth bit must be written to TB8 in SCON. When transmission
is initiated, the 8 data bits from SBUF are loaded into the
transmit shift register (LSB first). The 9
is loaded into the 9th bit position of the transmit shift register.
The transmission starts at the next valid baud rate clock. The
transmit interrupt flag, TI, is set as soon as the transmission has
completed, when the stop bit appears on TxD.
All of the following conditions must be met at the time the final
shift pulse is generated to receive a character:
If any of these conditions are not met, the received frame is
irretrievably lost, and the receive interrupt flag, RI, is not set.
Reception for Mode 2 is similar to that of Mode 1. The 8 data
bytes are input at RxD (LSB first) and loaded onto the receive
shift register. If the received frame has met the above criteria,
the following events occur:
Mode 3 (9-Bit UART with Variable Baud Rate)
Mode 3 is selected by setting both SM0 and SM1. In this mode,
the 8051 UART serial port operates in 9-bit mode with a variable
baud rate. The baud rate is set by a timer overflow rate. Timer 1
If the extended UART is disabled (EXTEN=0 in the CFG
SFR), RI must be zero to receive a character. This ensures
that the data in SBUF will not be overwritten if the last
received character has not been read.
If multiprocessor communication is enabled by setting
SM2, the received 9
This ensures that only frames with the 9
that contain addresses, generate a receive interrupt.
The 8 bits in the receive shift register are latched into SBUF.
The 9th data bit is latched into RB8 in SCON.
The receiver interrupt flag (RI) is set.
th
bit clear are intended specifically for the
th
bit must be set to receive a character.
th
bit clear. Since the master has
th
bit is clear, the frame will not
th
data bit, held in TB8,
th
th
bit set, frames
bit is set to
th
bit set is
th
bit set and
Rev. PrD | Page 120 of 140
th
or Timer 2 can be used to generate baud rates or both timers
can be used simultaneously where one generates the transmit
rate and the other generates the receive rate. There is also a
dedicated timer for baud rate generation, UART Timer, which
has a fractional divisor to precisely generate any baud rate—see
the UART Timer Generated Baud Rates section. The operation
of the 9-bit UART is the same as for Mode 2, but the baud rate
can be varied.
In all four modes, transmission is initiated by any instruction
that uses SBUF as a destination register. Reception is initiated in
Mode 0 when RI = 0 and REN = 1. Reception is initiated in the
other modes by the incoming start bit if REN = 1.
UART BAUD RATE GENERATION
Mode 0 Baud Rate Generation
The baud rate in Mode 0 is fixed:
Mode 2 Baud Rate Generation
The baud rate in Mode 2 depends on the value of the SMOD bit
in the PCON SFR. If SMOD = 0, the baud rate is 1/32 of the
core clock. If SMOD = 1, the baud rate is 1/16 of the core clock:
Modes 1 and 3 Baud Rate Generation
The baud rates in Modes 1 and 3 are determined by the overflow
rate of the timer generating the baud rate: either Timer 1 or
Timer 2 or the dedicated baud rate generator, UART Timer,
which has an integer and fractional divisor.
Timer 1 Generated Baud Rates
When Timer 1 is used as the baud rate generator, the baud rates
in Modes 1 and 3 are determined by the Timer 1 overflow rate
and the value of SMOD as follows:
The Timer 1 interrupt should be disabled in this application.
The timer itself can be configured for either timer or counter
operation, and in any of its three running modes. In the most
typical application, it is configured for timer operation in
autoreload mode (high nibble of TMOD = 0010 binary). In that
case, the baud rate is given by the formula
Timer 2 Generated Baud Rates
Baud rates can also be generated by using Timer 2. Using Timer 2
is similar to using Timer 1 in that the timer must overflow 16
times before a bit is transmitted or received. Because Timer 2
has a 16-bit autoreload mode, a wider range of baud rates is
Mode 0 Baud Rate =
Mode 2 Baud Rate =
Modes 1 and 3 Baud Rate =
Modes 1 and 3 Baud Rate =
Preliminary Technical Data
2
F
SMOD
12
32
core
2
2
SMOD
SMOD
32
32
× F
core
(
× Timer 1 Overflow Rate
256
F
core
TH
) 1