OM6211 NXP Semiconductors, OM6211 Datasheet - Page 20

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

Philips Semiconductors
11.2.2
In the read mode of the interface the microcontroller reads
data from the OM6211. To do so the microcontroller first
has to send the read status command, and then the
following byte is transmitted in the opposite direction
(using SDOUT). After that SCE is required to go HIGH
before a new command is sent (see Fig.15).
The OM6211 samples the SDIN data on the rising edges
of SCLK, but shifts SDOUT data on the falling edges of
SCLK. Thus the microcontroller is supposed to read
SDOUT data on the rising edges of SCLK.
After the read status command has been sent, the SDIN
line must be set to 3-state not later then the falling SCLK
edge of the last bit (see Fig.15).
The 8th read bit is shorter than the others because it is
terminated by the rising edge of SCLK (see Fig.15). The
last rising edge of SCLK sets SDOUT to 3-state after the
delay time t
There are 5 bits of information only that can be read by the
microcontroller (see Table 7). Two of them are chip
identification bits and have fixed values. The next two bits
are LCD module identification bits and can be set by
connecting the ID3 and ID4 pins to V
bit is the V
It indicates that the charge pump is running and the
voltage level of V
contrast of the display (VM = 1). If the V
cannot produce a voltage defined by V
2002 Jan 17
handbook, full pagewidth
48
SDOUT
SCLK
SDIN
SCE
R
84 dot matrix LCD driver
LCD
EAD MODE
3
(see Section 10.1 and Fig.17).
voltage monitor bit VM.
LCD
D/C
is sufficient to provide enough
DB7
DB6 DB5 DB4
DD1
OP
LCD
or V
, then VM = 0.
DB3 DB2 DB1 DB0
generator
SS
. The fifth
Fig.15 Read mode.
20
VM has a valid value 45 ms after a delay time of
approximately 45 ms starting from the time the V
generator has been switched on (by setting HVE = 1). This
delay time is dependent on the external V
capacitor (here 100 nF is assumed).
For more details concerning the VM bit see Chapter 22
The reading out of the chip identification bits and module
identification bits can be used to implement different
initialization schemes for different applications. The
reading out of VM can be used to check the proper
electrical contacts of the LCD module.
One read status command enables one status bit to be
read, i.e. 5 commands are needed to read the status of all
5 bits. The first 4 bits of the read byte (DB7 to DB4) are
always equal to the corresponding status bit and the next
4 bits (DB3 to DB0) are equal to the complement of this bit.
As stated before the SDOUT data is supposed to be read
on the rising edge of SCLK. Care must be taken, however,
when running the SCLK at maximum frequency. Because
of the access time limit t
might happen that the first bits of each group (DB7 to DB4
and DB3 to DB0) are not valid at the time of the
corresponding SCLK edges. Thus it is recommended to
read the bits DB4 and DB0 only.
DB7 DB6 DB5 DB4 DB3 DB2 DB1
2
(see Section 10.1 and Fig.17) it
DB0
Product specification
LCD
OM6211
MGU282
decoupling
D/C
LCD