SMB239
I2C PROGRAMMING INFORMATION
SERIAL INTERFACE
After the last byte is clocked in and the host receives
an Acknowledge, a Stop condition must be issued to
initiate the nonvolatile write operation.
READ
Access to the configuration registers, command and
status registers is carried out over an industry
standard 2-wire serial interface (I2C). SDA is a bi-
directional data line and SCL is a clock input (Figure4).
Data is clocked in on the rising edge of SCL and
clocked out on the falling edge of SCL. All data
transfers begin with the MSB. During data transfers,
SDA must remain stable while SCL is high. Data is
transferred in 8-bit packets with an intervening clock
period in which an Acknowledge is provided by the
device receiving data. The SCL high period (tHIGH) is
used for generating Start and Stop conditions that
precede and end most transactions on the serial bus.
A high-to-low transition of SDA while SCL is high is
considered a Start condition while a low-to-high
transition of SDA while SCL is high is considered a
Stop condition.
The address pointer for the non-volatile configuration
registers and memory registers as well as the volatile
command and status registers must be set before data
can be read from the SMB239. This is accomplished
by issuing a dummy write command, which is a write
command that is not followed by a Stop condition. A
dummy write command sets the address from which
data is read. After the dummy write command is
issued, a Start command followed by the address byte
is sent from the host. The host then waits for an
Acknowledge and then begins clocking data out of the
slave device. The first byte read is data from the
address pointer set during the dummy write command.
Additional bytes can be clocked out of consecutive
addresses with the host providing an Acknowledge
after each byte. After the data is read from the desired
registers, the read operation is terminated by the host
holding SDA high during the Acknowledge clock cycle
and then issuing a Stop condition. Refer to Figure 12
for an illustration of the read sequence.
The interface protocol allows operation of multiple
devices and types of devices on a single bus through
unique device addressing.
The address byte is
comprised of a 7-bit device type identifier (slave
address). The remaining bit indicates either a read or
a write operation. Refer to Table 1 for a description of
the address bytes used by the SMB239.
CONFIGURATION REGISTERS
The device type identifier for the configuration
registers and the command and status registers are
accessible with the same slave address. The slave
address can be can be programmed to any seven bit
number 0000000BIN through 1111111BIN. Table 3.
Writing and reading the configuration registers is
shown in Figures 10, 11 and 12. A description of the
configuration registers is shown in Table 3 through
Table 12.
GRAPHICAL USER INTERFACE (GUI)
WRITE
Device configuration utilizing the Windows based
SMB239 graphical user interface (GUI) is highly
recommended. The software is available from the
Summit website (www.summitmicro.com). Using the
GUI in conjunction with this datasheet, simplifies the
process of device prototyping and the interaction of
the various functional blocks. A programming Dongle
(SMX3202) is available from Summit to communicate
with the SMB239. The Dongle connects directly to the
USB port of a PC and programs the device through a
cable using the I2C bus protocol. See Figure 9 and the
SMX3202 Data Sheet.
Writing to a configuration register is illustrated in
Figures 10 and 11. A Start condition followed by the
slave address byte is provided by the host; the
SMB239 responds with an Acknowledge; the host then
responds by sending the memory address pointer or
configuration register address pointer; the SMB239
responds with an acknowledge; the host then clocks in
one byte of data. For configuration register writes, up
to 15 additional bytes of data can be clocked in by the
host to write to consecutive addresses within the same
page.
Slave Address
ALL
Register Type
Configuration Registers are located in 00 HEX thru
05 HEX , 07HEX, 0CHEX, 0EHEX and 0FHEX
Table 3 – Address bytes used by the SMB239.
Summit Microelectronics, Inc
2129 3.0 2/23/2009
19
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
