OM6211 NXP Semiconductors, OM6211 Datasheet - Page 18

• Manufacturer Part Number: OM6211
• Description: 48 X 84 Dot Matrix Lcd Driver
• Manufacturer: NXP Semiconductors

Philips Semiconductors
11.2
The serial interface is a 3-line bidirectional interface for
communication between the microcontroller and the LCD
driver chip. The 3 lines are: SCE (chip enable), SCLK
(serial clock) and SDA (serial data). The OM6211 is
connected to SDA by two pins: SDIN (data input) and
SDOUT (data output) connected together.
11.2.1
The write mode of the interface means that the
microcontroller writes commands and data to the OM6211.
Each data packet contains a control bit D/C and a
transmission byte. If D/C is LOW, the following byte is
interpreted as a command byte (see Table 5). If D/C is
HIGH, the following byte is stored in the display data RAM.
After every data byte the address counter is incremented
automatically. Figure 11 shows the general format of the
write mode and the definition of the transmission byte.
Every command can be sent in any order to the OM6211.
The MSB of a byte is transmitted first. The serial interface
is initialized when SCE is HIGH. In this state, SCLK clock
pulses have no effect and no power is consumed by the
serial interface. A falling edge on SCE enables the serial
interface and indicates the start of a data transmission.
2002 Jan 17
handbook, full pagewidth
48
Serial interface
W
84 dot matrix LCD driver
RITE MODE
Transmission Byte (TB) (command byte OR data byte)
D/C DB7 DB6 DB5 DB4 DB3
D/C
MSB
TB
DB2 DB1 DB0
Fig.11 Serial data stream, write mode.
D/C
LSB
TB
18
Figures 12, 13 and 14 show the protocol of the write
mode:
When SCE is HIGH, SCLK clocks are ignored: during
the HIGH time of SCE the serial interface is initialized
(see Fig.12)
At the falling edge of SCE SCLK must be LOW (see
Fig.16); for the transmission of each data bit a rising and
then a falling edge of SCLK is necessary
SDIN is sampled at the rising edge of SCLK
D/C indicates whether the byte is a command (D/C = 0)
or RAM data (D/C = 1); it is sampled with the first rising
SCLK edge
If SCE stays LOW after the last bit of a command or data
byte, the serial interface expects the D/C bit of the next
byte at the next rising edge of SCLK (see Fig.13)
A reset pulse with RES interrupts the transmission. The
data being written into the RAM may be corrupted. The
registers are cleared. If SCE is LOW after the rising
edge of RES, the serial interface is ready to receive the
D/C bit of a command or data byte (see Fig.14).
D/C
TB
Product specification
MGU278
OM6211