ade7953 Analog Devices, Inc., ade7953 Datasheet - Page 50

• Manufacturer Part Number: ade7953
• Description: Single Phase, Multifunction Metering Ic With Neutral Current Measurement Ade7953
• Manufacturer: Analog Devices, Inc.

ADE7953
COMMUNICATING WITH THE ADE7953
All ADE7953 features can be accessed via a group of on-chip
registers. For a detailed list of all the registers, see the ADE7953
Registers section. Three different communication interfaces can
be used to access the on-chip registers.
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•
•
All three communication options use the same group of pins
and, therefore, only one method of communication should be
used in each design.
COMMUNICATION AUTODETECTION
The ADE7953 contains a detection system that automatically
detects which of the three communication interfaces is being
used. This feature allows communication to be quickly estab-
lished with minimal initialization. Autodetection works by
monitoring the status of the four communication pins and
automatically selecting the communication interface that
matches the configuration (see Table 9).
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Table 9. Communication Autodetection
Communication Interface
SPI
I
UART
2
C
4-pin SPI interface
2-pin bidirectional I
2-pin UART interface
The CS pin (Pin 28) is used to determine whether the
communication method is SPI. If this pin is held low, the
communication interface is set to SPI.
The SCLK pin (Pin 25) is used to determine whether the
communication method is I
high, the communication interface is set to I
low, the communication interface is set to UART.
2
C interface
Pin 28 (CS)
0
1
1
2
C or UART. If this pin is held
2
C; if it is held
Pin 25 (SCLK)
Don’t care
1
0
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Therefore, although Pin 25 (SCLK) and Pin 28 (CS) are not
required if communicating via I
be configured in hardware as shown in Table 9 to ensure the
functionality of the autodetection system.
LOCKING THE COMMUNICATION INTERFACE
After the selected communication interface is established, the
interface should be locked to prevent the communication
method from inadvertently changing. The ADE7953 can be
configured to lock automatically after the first successful
communication.
The automatic lock feature is disabled by default and is enabled
by clearing the COMM_LOCK bit (Bit 15) in the CONFIG
register (Address 0x102). To successfully establish and lock the
communication interface, a write should be issued shortly after
power-up to the CONFIG register, clearing the COMM_LOCK
bit and thus locking the communication interface. When the
communication interface is locked to a specific method (that is,
SPI, I
changed without resetting the ADE7953.
Note that if using the SPI communication interface to lock
the communication mode, the CS pin must be held low for a
minimum of 1.2 μs after the last SCLK. This delay is required
only when writing to the COMM_LOCK bit (see the SPI
Interface Timing section).
2
C, or UART), the communication method cannot be
Pin 27 (MOSI/SCL/Rx)
MOSI
SCL
Rx
2
C or UART, these pins should
Pin 26 (MISO/SDA/Tx)
MISO
SDA
Tx