CP2400 SILABS [Silicon Laboratories], CP2400 Datasheet - Page 36

• Manufacturer Part Number: CP2400
• Description: 128/64 SEGMENT LCD DRIVER
• Manufacturer: SILABS [Silicon Laboratories]

CP2400/1/2/3
6.2.
The SMBus interface supports 6 commands which provide access to all internal registers and RAM. The six
commands are listed in Table 6.2. Detailed information on the SMBus interface including bus timing can be found in
Section “15. SMBus Interface” on page 104.
Figure 6.3 shows typical SMBus read and write transfers used to access internal registers or RAM. The first three
bytes of a write transfer are interpreted as COMMAND, ADDRH, and ADDRL. For the REGPOLL, REGREAD, and
RAMREAD commands, a repeated start is required to begin data transfer. The host controller may also choose to
end the transfer with a STOP and then start a new read transfer using the same setup information. For the WRITE
and RAMWRITE command, an SMBus write transfer is required. Starting with the fourth byte following the slave
address, all bytes written are interpreted as data. The SMBus transfer ends when the host sends a STOP.
Note: Using the RAMREAD command to read an address outside the 0x400–0x4FF range will result in a data value of 0xDE.
36
REGPOLL
REGREAD
REGSET
REGWRITE
RAMREAD
RAMWRITE
Accessing Internal Registers and RAM over the SMBus Interface
SMBus Read (Data Transfer):
Command
SMBus Read (Setup):
SMBus Write:
S
S
R
S
SLA
SLA
SLA
W
W
R
Received by
CP240x
Transmitted by
CP240x
A
A
A
OPCODE
COMMAND
COMMAND
0x01
0x02
0x03
0x06
0x08
Data 0
0x04
Table 6.2. SMBus Command Set
A
Figure 6.3. SMBus Transfers
Writes one or more bytes to a single register. Used for generating a
A
A
Reads one or more bytes from registers with sequential addresses.
waveform on a GPIO pin or updating the SmaRTClock registers.
Writes one or more bytes to registers with sequential addresses.
Reads data from a single register. Used for polling a status bit.
ADDRH
ADDRH
Reads one or more bytes from sequential RAM locations.
S = START
R = REPEATED START
P = STOP
A = ACK
N = NACK
Writes one or more bytes to sequential RAM locations.
Data N
Rev. 1.0
A
A
N
ADDRL
ADDRL
P
A
A
Description
Data 0
+ Data Transfer or STOP
R = READ
W = WRITE
SLA = Slave Address
A
Data N
A
P