Difference between revisions of "Arduino: How to control a HD44780 based character LCD"
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Lukas Dzunko (talk | contribs) (→Return Home) |
Lukas Dzunko (talk | contribs) (→Return Home) |
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| 0 || 0 || || 0 || 0 || 0 || 0 || 0 || 0 || 1 || x || || ~ 1.52 ms | | 0 || 0 || || 0 || 0 || 0 || 0 || 0 || 0 || 1 || x || || ~ 1.52 ms | ||
|} | |} | ||
| − | * AC to DDRAM and 0x00 | + | * Set AC to DDRAM and 0x00 |
* Return cursor and display to home (original) postition | * Return cursor and display to home (original) postition | ||
Revision as of 15:17, 9 December 2012
Many characters LCD displays use so called HD44780 based protocol on interface. This is more like standard but i recommend to check datasheet from vendor. There can be small modifications and/or difference in timing. Especially timing is important. If communication rate is too quick, then LCD drop data or misbehave depending on internal state. I recommend to check busy flag if possible. If not then correct delay should be applied between commands. Result of commands can be checked via LCD Simulator prior to programing MCU. For example i like this one: DjLCDSIM.
Contents
Command Set
Clear Display
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | ~ 1.52 ms |
- Clear display data by writing 0x20 ("space") to whole DDRAM memory
- Set AC to DDRAM and 0x00
- Set entry mode to increment (I/D = 1)
Return Home
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | x | ~ 1.52 ms |
- Set AC to DDRAM and 0x00
- Return cursor and display to home (original) postition
Entry Mode Set
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | I/D | SH | ~ 38 us |
Display ON / OFF Control
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 | 1 | D | C | B | ~ 38 us |
Cursor or Display Shift
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 1 | S/C | R/L | x | x | ~ 38 us |
Function set
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 1 | DL | N | F | x | x | ~ 38 us |
Set CGRAM Address
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 1 | AC5 | AC4 | AC3 | AC2 | AC1 | AC0 | ~ 38 us |
Set DDRAM Address
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 1 | AC6 | AC5 | AC4 | AC3 | AC2 | AC1 | AC0 | ~ 38 ms |
Read Busy Flag and Address
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | BF | AC6 | AC5 | AC4 | AC3 | AC2 | AC1 | AC0 | ~ 0 us |
Write data to RAM
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 0 | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | ~ 38 us |
Read data from RAM
| RS | R/W | DB7 | DB6 | DB5 | DB4 | DB3 | DB2 | DB1 | DB0 | Execution Time | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | ~ 38 us |
