pcf2104 NXP Semiconductors, pcf2104 Datasheet - Page 23

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pcf2104

Manufacturer Part Number
pcf2104
Description
Pcf2104x Lcd Controller/driver
Manufacturer
NXP Semiconductors
Datasheet
Philips Semiconductors
9.7
‘Set CGRAM address’ sets bits 0 to 5 of the CGRAM
address (A
(binary A[5] to A[0]). Data can then be written to or read
from the CGRAM.
Only bits 0 to 5 of the CGRAM address are set by the
‘Set CGRAM address’ instruction. Bit 6 can be set using
the ‘Set DDRAM address’ instruction or by using the
auto-increment feature during CGRAM write. All bits 0 to 6
can be read using the ‘Read busy flag and address’
instruction.
9.8
Set DDRAM address sets the DDRAM address (A
Table 3) into the Address Counter (binary A[6] to A[0).
Data can then be written to or read from the DDRAM.
Table 5 Hexadecimal address ranges
9.9
‘Read busy flag and address’ reads the Busy Flag (BF).
When BF = logic 1 it indicates that an internal operation is
in progress. The next instruction will not be executed until
BF = logic 0, so BF should be checked before sending
another instruction.
At the same time, the value of the Address Counter
expressed in binary A[6] to A[0] is read out. The Address
Counter is used by both CGRAM and DDRAM and its
value is determined by the previous instruction.
9.10
Writes binary 8-bit data D[7] to D[0] to the CGRAM or the
DDRAM.
Whether the CGRAM or DDRAM is to be written to is
determined by the previous specification of CGRAM or
DDRAM address setting. After writing, the address
automatically increments or decrements by 1, in
accordance with the entry mode. Only bits D0 to D4 of
CGRAM data are valid, bits D5 to D7 are ‘don't care’.
1997 Dec 16
00 to 4F
00 to 0B and 0C to 4F
00 to 27 and 40 to 67
00 to 13, 20 to 33, 40 to 53
and 60 to 73
LCD controller/driver
Set CGRAM address
Set DDRAM address
Read busy flag and address
Write data to CGRAM or DDRAM
ADDRESS
CG
in Table 3) into the Address Counter
1-line by 24
2-line by 12
2-line by 24
4-line by 12
FUNCTION
DD
in
23
9.11
Reads binary 8-bit data D[7] to D[0] from the CGRAM or
DDRAM.
The most recent ‘Set address’ instruction determines
whether the CGRAM or DDRAM is to be read.
The ‘Read data’ instruction gates the content of the data
register (DR) to the bus while E = HIGH. After E goes
LOW again, internal operation increments (or decrements)
the AC and stores RAM data corresponding to the new AC
into the DR.
Remark: the only three instructions that update the data
register (DR) are:
Other instructions (e.g. ‘Write data, ‘Cursor/display shift’,
‘Clear display’, ‘Return home’) will not modify the data
register content.
10 INTERFACE TO MICROCONTROLLER
The PCF2104x can send data in either two 4-bit operations
or one 8-bit operation and can thus interface to 4-bit or
8-bit microcontrollers.
In the 8-bit mode data is transferred as 8-bit bytes using
the 8 data lines DB0 to DB7. Three further control lines E,
RS, and R/W are required.
In the 4-bit mode data is transferred in two cycles of 4-bits
each. The higher order bits (corresponding to DB4 to DB7
in 8-bit mode) are sent in the first cycle and the lower order
bits (DB0 to DB3 in 8-bit mode) in the second cycle.
Data transfer is complete after two 4-bit data transfers.
It should be noted that two cycles are also required for the
Busy Flag check. 4-bit operation is selected by instruction.
See Figs 15, 16 and 17 for examples of bus protocol.
In the 4-bit mode pins DB3 to DB0 must be left
open-circuit. They are pulled up to V
‘Set CGRAM address’
‘Set DDRAM address’
‘Read data’ from CGRAM or DDRAM.
(PARALLEL INTERFACE)
Read data from CGRAM or DDRAM
DD
Product specification
PCF2104x
internally.

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