HD44780 character LCD module interface connection guide

• 5 V logic
  • VCC (2)
  • 5 V supply
  • RV1 high
  • C1.1
• Ground
  • VSS (1)
  • R/W (5)
  • Supply return
  • Controller ground
  • RV1 low
  • C1.2
• Contrast bias
  • VEE (3)
  • RV1 wiper
• Enable held low
  • E (6)
  • Controller enable output

Bench checks

• Verify 5 V at VCC relative to VSS. Adjust the contrast with the display under normal viewing conditions.

Optrex DMC16230-AAE-DW No. 2000-0270, § 4.2. Local bypass is a fixture choice.

Write characters with six controller outputs

• 5 V logic
  • VCC (2)
  • 5 V supply
  • RV1 high
  • C1.1
• Ground
  • VSS (1)
  • R/W (5)
  • Supply return
  • Controller ground
  • RV1 low
  • C1.2
• Contrast bias
  • VEE (3)
  • RV1 wiper
• Register select
  • RS (4)
  • Controller RS output
• Enable
  • E (6)
  • Controller E output
• Data bit 4
  • DB4 (11)
  • Controller bit 0
• Data bit 5
  • DB5 (12)
  • Controller bit 1
• Data bit 6
  • DB6 (13)
  • Controller bit 2
• Data bit 7
  • DB7 (14)
  • Controller bit 3

Bench checks

• After VCC is stable, wait 40 ms. Send the single nibbles 0x3, 0x3, 0x3 and 0x2 with at least 5 ms after the first and 200 µs after each subsequent nibble.
• Send 0x28, 0x08, 0x01, 0x06 and 0x0C as two-nibble commands. Allow 3 ms after clear and 100 µs after other commands.
• Write a test character with RS high. Confirm upper nibble first and check contrast before diagnosing firmware.

Hitachi HD44780U data sheet, Figure 24 and instruction table. Delay values are fixture choices above the listed timings.

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

The pin map follows the Optrex DMC16230-AAE-DW 14-contact module. Optrex permits a controller equivalent to HD44780. Backlit modules and bare controller packages use their own mechanical drawings.

DMC16230-AAE-DW

16 characters × 2 lines, fourteen electrical contacts.

• Optrex DMC16230-AAE-DW No. 2000-0270· Archive copy of Optrex’s module specification. See §§ 2 and 4.
• Hitachi HD44780U data sheet· Distributor copy of the Hitachi controller data sheet. Bus timing, instruction table and 4-bit initialization.
• Source register· Document revisions, applicable order codes, consulted sections and available file checksums.