ADSST-EM-2030 Analog Devices, ADSST-EM-2030 Datasheet - Page 3

• Manufacturer Part Number: ADSST-EM-2030
• Description: 3-Phase Electronic Energy Meter Chipset
• Manufacturer: Analog Devices

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DataSheet
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SERIAL PERIPHERAL INTERFACE (SPI)
The SPI bus available on the ADSST-EM-2030 is useful to
communicate to an external microcontroller as shown in Figure 1.
Here, the microcontroller functions as master and the ADSST-
EM-2030 is a slave for this protocol. Using this communication
port, the microcontroller will be able to read and write to the
ADSST-EM-2030 to perform the following functions:
•
•
•
Four pins are used on the ADSST-EM-2030 chipset for the
communication, and are shown Table I.
Pin No.
22
23
24
25
TIMING SPECIFICATIONS
This section contains timing information for the ADSST-EM-
2030 chipset.
General Notes
Use the exact timing information given. Do not attempt to
derive parameters from the addition or subtraction of others.
While addition or subtraction would yield meaningful results for
an individual device, the values given in this data sheet reflect
statistical variations and worst cases. Consequently, parameters
cannot be added up meaningfully to derive longer times.
REV. 0
Figure 1. SPI Communication between ADSST-EM-2030
and Microcontroller
Calibrate the meter
Configure the ADSST-EM-2030 chipset
Read measured parameters from the ADSST-EM-2030 chipset
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Table I. Pin Description for SPI Communication Port
ADSST-EM-2030
SLAVE
Mnemonic
SS
MISO
MOSI
SCLK
MICROCONTROLLER
MASTER
Description
Select
Output
Input
SPI Clock
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Timing Notes
Switching characteristics specify how the processor changes its
signals. Designers have no control on this timing—circuitry exter-
nal to the processor must be designed for compatibility with these
signal characteristics. These characteristics can be used to ensure
that any timing requirement of a microcontroller connected to
the chipset is satisfied.
Timing requirements apply to signals that are controlled by circuitry
external to the chipset, such as the data input for a read operation.
Timing requirements guarantee that the chipset operates cor-
rectly with the external microcontroller.
Data Access
Data can be written or read to the ADSST-EM-2030 chipset only
when the SS pin is low. Since the chipset is a slave, the external
controller must bring the SS pin low, the SCLK clock should be
sent to clock in or clock out the data. For sending the data to the
chipset, data should be sent on MOSI pin; for receiving the data
from the chipset, data should be collected on MISO pin.
With the external microcontroller as the master for the SPI
communication, the microcontroller should send eight succes-
sive clocks to the ADSST-EM-2030 every 5 ms. At this instant,
the microcontroller may either send a command or data or may
receive an acknowledgment followed by data from the chipset.
The ADSST-EM-2030 maintains a time gap of 5 ms between
transmission of two successive bytes to or from the microcontroller.
This helps in avoiding clashing of interrupts while the chipset
and the microcontroller are executing their respective tasks.
Timing Parameter
t
t
t
t
t
t
t
t
t
t
t
SS
SC
SH
DAV
DSU
DHD
DF
DR
SR
SF
SFS
SS to SCLOCK Edge
SCLOCK Low
Pulsewidth
SCLOCK High
Pulsewidth
Data Output Valid
after SCLOCK Edge
Data Input Setup Time
before SCLOCK Edge
Data Input Hold Time
before SCLOCK Edge
Data Output Fall Time
Data Output Rise Time
SCLOCK Rise Time
SCLOCK Fall Time
SS High after
SCLOCK Edge
Table II. SPI Pin Timings
ADSST-EM-2030
Min
0
100
100
0
Typ Max Unit
300
300
10
10
10
10
50
25
25
25
25
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns