SMB239 datasheet(19/30 Pages) SUMMIT

19 / 30 page

SMB239

Summit Microelectronics, Inc

2129 3.0 2/23/2009

I2C PROGRAMMING INFORMATION

SERIAL INTERFACE

Access to the configuration registers, command and

status registers is carried out over an industry

standard 2-wire serial interface (I

2C). 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 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.

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.

WRITE

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.

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

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.

CONFIGURATION REGISTERS

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)

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 I

2C bus protocol. See Figure 9 and the

SMX3202 Data Sheet.

Slave Address

ALL

Configuration Registers are located in 00 HEX thru

05 HEX , 07HEX, 0CHEX, 0EHEX and 0FHEX

Table 3 – Address bytes used by the SMB239.

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