ade7854 Analog Devices, Inc., ade7854 Datasheet - Page 49

• Manufacturer Part Number: ade7854
• Description: Poly Phase Multifunction Energy Metering Ic With Neutral Current Measurement
• Manufacturer: Analog Devices, Inc.

Preliminary Technical Data
SPI Read Operation
The read operation using the SPI interface of the ADE7854
initiates when the master sets SS pin low and begins sending
ADE7854
S
A
R
S 0 1 1 1 0 0 0
S
A
R
S
T
T
T
T
0 1 1 1 0 0 0
Figure 62. Connecting ADE7854 SPI with an SPI device
slave address
slave address
SCLK
MOSI
MISO
SS\
ADE7854/ADE7858
ACK generated by
0
1
A
C
K
A
C
K
15
31
Byte3 (MS) of reg
MS 8 bits of reg
MOSI
MISO
SCK
SS\
address
ADE7854/ADE7858
Figure 61. I
ACK generated by
device
SPI
16
8
A
C
K
A
C
K
2
C Read Operation of a 32-bit register
15
7
Rev. PrC| Page 49 of 71
LS 8 bits of reg
Byte2 of reg
address
one byte representing the address of the ADE7854 on the MOSI
line. The master sets data on the MOSI line starting with the
first high to low transition of SCLK. The SPI of the ADE7854
samples data on the low to high transitions of SCLK. The most
significant 7 bits of the address byte can have any value, but as a
good programming practice, they should be different from
b#0111000, the 7 bits used in the I
(READ/ WRITE ) of the address byte must be 1 for a read
operation. Next, the master sends the 16-bit address of the
register that is read. After the ADE7854 receives the last bit of
address of the register on a low to high transition of SCLK, it
begins to transmit its content on the MISO line before the next
SCLK high to low transition occurs, so the master can sample
the data on this SCLK transition. After the master receives the
last bit, it sets SS and SCLK lines high and the communication
ends. The data lines MOSI and MISO go in high impedance
state.
See Figure 63 for details of the SPI read operation.
ACK generated by
8
0
Master
A
C
K
A
C
K
7
Byte1of reg
0
A
C
K
2
C protocol. Bit 0
7
Byte0 (LS) of reg
ADE7854
0
N
O
A
C
K
O
S
T
P
S