50 MicroBlaze Development Kit Spartan-3E 1600 Edition User Guide
www.xilinx.com UG257 (v1.1) December 5, 2007
Chapter 5: Character LCD Screen R
After the write operation, the address is automatically incremented or decremented by 1
according to the Entry Mode Set command. The entry mode al so dete rmines d isplay shift.
Execution Time: 40Ps

Read Data from CG RAM or DD RAM

Read data from DD RAM if the command follows a previous Set DD RAM Address
command, or read data from CG RAM if the command follows a previous Set CG RAM
Address command.
After the read operation, the address is automatically incremented or decremented by 1
according to the Entry Mode Set command. However, a display shift is not executed
during read operations.
Execution Time: 40Ps
Operation

Four-Bit Data Interface

The board uses a 4-bit data interface to the character LCD.
Figure 5-6 illustrates a write operation to the LCD, showing the minimum times allowed
for setup, hold, and enable pulse length relative to the 50 MHz clock (20 ns period)
provided on the board.
Figure 5-6: Character LCD Interface Timing
Upper
4 bits
Lower
4 bits
1 µs40 µs
40 ns10 ns
230 ns
Valid Data
CLOCK
LCD_RS
SF_D[11:8]
LCD_RW
LCD_E
LCD_RS
SF_D[11:8]
LCD_RW
LCD_E
0 = Command, 1 = Data
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