AMIS-49587_15 Datasheet, PDF (18/56 Pages) ON Semiconductor – Power Line Carrier Modem

AMIS−49587
a more reliable reconstruction of the synchronization. This
PLL permits as well a safer implementation of the
”repetition with credit” function (also known as chorus
transmission). The clock generator makes use of a precise
quartz oscillator master. The clock signals are then obtained
by the use of a programmed division scheme. The support
circuits are also contained in this block. The support circuits
include the necessary blocks to supply the references
voltages for the AD and DA converters, the biasing currents
and power supply sense cells to generate the right power off
and startup conditions.
24 bit @ 1200 baud
20 ms
Figure 10. Data Stream is in Sync with Zero
Crossings of the Mains (Example for 50 Hz)
5.2.3 Communication Controller
The Communication Controller block includes the
micro−processor, its peripherals: RAM, ROM, UART,
TIMER, and the Power on reset. The processor uses the
ARM Reduced Instruction Set Computer (RISC)
architecture optimized for IO handling. For most of the
instructions, the machine is able to perform one instruction
per clock cycle. The microcontroller contains the necessary
hardware to implement interrupt mechanisms, timers and is
able to perform byte multiplication over one instruction
cycle. The microcontroller is programmed to handle the
physical layer (chip synchronization), and the MAC layer
conform to IEC 61334−5−1. The program is stored in a
masked ROM. The RAM contains the necessary space to
store the working data. The back−end interface is done
through the Serial Communication Interface block. This
back−end is used for data transmission with the application
micro controller (containing the application layer for
concentrator, power meter, or other functions) and for the
definition of the modem configuration.
5.2.4 Local Port
The controller uses 3 output ports to inform about the
actual status of the PLC communication. RX_DATA
indicates if Receiving is in progress, or if AMIS−49587 is
waiting for synchronization, or of it configures. CRC
indicates if the received frames are valid (CRC = OK).
TX_DATA / PRE_SLOT is the output for either the
transmitting data (TX_DATA) or a synchronization signal
with the time−slots (PRE_SLOT).
5.2.5 Serial Communication Interface
The local communication is a half duplex asynchronous
serial link using a receiving input (RxD) and a transmitting
output (TxD). The input port T_REQ is used to manage the
local communication with the application micro controller
and the baud rate can be selected depending on the status of
two inputs BR0, BR1. These two inputs are taken in account
after an AMIS−49587 reset. Thus when the application
micro controller wants to change the baud rate, it has to set
the two inputs and then provoke a reset.
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