EVAL-AD5933EB Datasheet, PDF (28/40 Pages) Analog Devices – 1 MSPS, 12-Bit Impedance Converter, Network Analyzer

AD5933
Data Sheet
WRITING/READING TO THE AD5933
The interface specification defines several different protocols
for different types of read and write operations. This section
describes the protocols used in the AD5933. The figures in this
section use the abbreviations shown in Table 15.
Table 15. I²C Abbreviation Table
Abbreviation Condition
S
Start
P
Stop
R
Read
W
Write
A
Acknowledge
A
No acknowledge write byte/command byte
User Command Codes
The command codes in Table 16 are used for reading/writing to
the interface. They are further explained in this section, but are
grouped here for easy reference.
Table 16. Command Codes
Command Code
Code
Name Code Description
1010 0000 Block
write
This command is used when writing
multiple bytes to the RAM; see the
Block Write section.
1010 0001 Block
read
This command is used when reading
multiple bytes from RAM/memory;
see the Block Read section.
1011 0000
Address
pointer
This command enables the user to set
the address pointer to any location in
the memory. The data contains the
address of the register to which the
pointer should be pointing reworded
Write Byte/Command Byte
In this operation, the master device sends a byte of data to the
slave device. The write byte can either be a data byte write to a
register address or can be a command operation. To write data
to a register, the command sequence is as follows (see Figure 30):
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
write bit (low).
3. The addressed slave device asserts an acknowledge on SDA.
4. The master sends a register address.
5. The slave asserts an acknowledge on SDA.
6. The master sends a data byte.
7. The slave asserts an acknowledge on SDA.
8. The master asserts a stop condition on SDA to end the
transaction.
S
SLAVE
ADDRESS
W
A
REGISTER
ADDRESS
A
REGISTER
DATA
A
P
Figure 30. Writing Register Data to Register Address
The write byte protocol is also used to set a pointer to an
address (see Figure 31). This is used for a subsequent single-
byte read from the same address or block read or block write
starting at that address.
To set a register pointer, the following sequence is applied:
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
write bit (low).
3. The addressed slave device asserts an acknowledge on
SDA.
4. The master sends a pointer command code (see Table 16;
a pointer command = 1011 0000).
5. The slave asserts an acknowledge on SDA.
6. The master sends a data byte (a register address to where
the pointer is to point).
7. The slave asserts an acknowledge on SDA.
8. The master asserts a stop condition on SDA to end the
transaction.
S
SLAVE
ADDRESS
W
POINTER
REGISTER
A COMMAND A ADDRESS A
1011 0000
TO POINT TO
P
Figure 31. Setting Address Pointer to Register Address
BLOCK WRITE
In this operation, the master device writes a block of data to a
slave device (see Figure 32). The start address for a block write
must previously have been set. In the case of the AD5933 this is
done by setting a pointer to set the register address.
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by the
write bit (low).
3. The addressed slave device asserts an acknowledge on SDA.
4. The master sends an 8-bit command code (1010 0000) that
tells the slave device to expect a block write.
5. The slave asserts an acknowledge on SDA.
6. The master sends a data byte that tells the slave device the
number of data bytes to be sent to it.
7. The slave asserts an acknowledge on SDA.
8. The master sends the data bytes.
9. The slave asserts an acknowledge on SDA after each
data byte.
10. The master asserts a stop condition on SDA to end the
transaction.
S
SLAVE
ADDRESS
W
A
BLOCK
WRITE
A
NUMBER
BYTES WRITE
A
BYTE 0
A
BYTE 1
A
BYTE 2
A
P
Figure 32. Writing a Block Write
Rev. E | Page 28 of 40