Example Of Interface To A 4-bit MPU

Interface to a 4-bit MPU can be made through the I/O port of the 4-bit MPU. If there are sufficient I/O ports, data can be transferred at 8-bit cycles, however, if there are not, data transfer can be accomplished by two cycles of 4-bit transfers(selec interface as 4-bits long). Please take into account that 2 cycles of the BF check will be necessary and the timing sequence will prove to be complicated.

Features

1. Interface to an 8-bit or 4-bit MPU is available.
   
2. 192 types of alphanumerics, symbols and special characters can be displayed with the vuilt-in character generator(ROM).
   
3. Other preferred characters can be displayed by character generator(RAM)
   
4. Various instructions may be programmed.

*Clear display    *Cursor at home    *On/Off cursor
*Blink character    *Shift display    *Shift cursor
*Read/write display data….etc.

5. Compact and light weight design which can easily be integrated into end products.
   
6. single power supply +5V or +3V drive(except for extended temp. type).
   
7. Low power consumption.

Interface between data bus line and 4-bit or 8-bit MPU is available.

Data transfer requires two cycles in case of a 4-bit MPU, and once in case of an 8-bit MPU.

If Interface Data Is 4-bit long

Data transfer is accomplished through 4 bus lines from DB4 to DB7.(while the rest of 4 bus lines from DB0 to DB3 are not used.)

Data transfer is completed when 4-bits of data is transferred twice.(upper 4-bits of data, then lower 4-bits of data.)

If Interface Data Is 8-bits Long

Data transfer is made through all 8 bus lines from DB0 to DB7.