PRODUCT SPECIFICATION
TMC22x5yA
Reading (the R/W bit of the slave address byte HIGH)
Table 25. Serial Port Addresses
begins at the previously established base address. The
address of the read register autoincrements after each byte is
transferred.
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1
A
6
A
5
A
4
A
3
A
2
A
1
A
0
(MSB)
(SA ) (SA ) (SA )
2 1 0
To terminate a write sequence to the TMC22x5yA, a stop
signal must be sent. A stop signal comprises a LOW-to-
HIGH transition of SDA while SCL is HIGH. To terminate a
read sequence simply do not acknowledge (NOACK) the last
byte received and the TMC22x5yA will terminate the
sequence.
1
1
1
1
1
1
1
1
0
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
A repeated start signal occurs when the master device driv-
ing the serial interface generates a start signal without first
generating a stop signal to terminate the current communica-
tion. This is used to change the mode of communication
(read, write) between the slave and master without releasing
the serial interface lines.
Data Transfer via Serial Interface
For each byte of data read or written, the MSB is the first bit;
that is, bit 7 of the 8-bit sequence.
Serial Interface Read/Write Examples
Write to one control register
• Start signal
If the TMC22x5yA does not acknowledge the master device
during a write sequence, the SDA remains HIGH so the mas-
ter can generate a stop signal. If the master device does not
acknowledge the TMC22x5yA during a read sequence, the
Decoder interprets this as “end of data.” The SDA remains
HIGH so the master can generate a stop signal.
• Slave Address byte (R/W bit = LOW)
• Block Pointer (00)
• Base Address byte
• Data byte to base address
• Stop signal
Writing data to specific control registers of the TMC22x5yA
requires that the 8-bit address of the control register of inter-
est be written after the slave address has been established.
This control register address is the base address for subse-
quent write operations. The base address autoincrements by
one for each byte of data written after the data byte intended
for the base address. If more bytes are transferred than there
are available addresses, the address will not increment and
remain at its maximum value of 3Fh. Any base address
higher than 3Fh will not produce an ACKnowledge signal.
Write to four consecutive XLUT locations
• Start signal
• Slave Address byte (R/W bit = LOW)
• Block Pointer (01)
• Base Address byte
• Data byte to base address
• Data byte to (base address + 1)
• Data byte to (base address + 2)
• Data byte to (base address + 3)
• Stop signal
Data are read from the control registers of the TMC22x5yA
in a similar manner. Reading requires two data transfer
operations:
Read from one XLUT location
The base address must be written with the R/W\ bit of the
slave address byte LOW to set up a sequential read
operation.
• Start signal
• Slave Address byte (R/W bit = LOW)
SDA
t
BUFF
t
t
t
t
STOSU
DHO
DSU
STASU
t
STAH
t
DAL
SCL
t
BAH
65-22x5y-18
Figure 35. Serial Port Read/Write Timing
REV. 1.0.0 2/4/03
69
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
