HD44780

HD44780
Status	Stable
menuconfig	I/O->LCD Displays->HD44780 module driver (Character-LCD)
Pinning	yes
Ecmd	yes
Control6	yes
Depends on	ECMD
Requires	-
Code	https://github.com/ethersex/ethersex/tree/master/hardware/lcd

THIS WIKI PAGE IS CURRENTLY WORK IN PROGRESS

The HD44780 module provides support for common alphanumeric character LCDs using Hitachis HD44780 and compatible controllers.

Supported LC-Displays

The vast majority of all alphanumeric LC-Displays use Hitachis HD44780 dot matrix liquid crystal display (LCD) controller. The e6 HD44780 module supports displays of many different sizes utilizing the original HD44780 and compatible controllers.

Alphanumeric LCDs are mainly distinguished by their size, the start-address of the per line Display Data-RAM (DDRAM) and the controller type. The original HD44780 controllers can drive up to 80 characters - most displays with more characters use two independent controllers.

The following table lists the LC-displays supported by the e6 HD44780 module by size and per line DDRAM start-address:

Menuconfig	Size		DDRAM Startaddress				Note:
LCD size/type	Characters	Lines	Line 1	Line 2	Line 3	Line 4
8_Characters_1_Line	8	1	0x00	n/a	n/a	n/a
16_Characters_1_Line	16	1	0x00	n/a	n/a	n/a
16_Characters_1_Line_Mux16	16	1	0x00	n/a	n/a	n/a	organized as 8 chars, 2 lines
20_Characters_1_Line	20	1	0x00	n/a	n/a	n/a
40_Characters_1_Line	40	1	0x00	n/a	n/a	n/a
8_Characters_2_Lines	8	2	0x00	0x40	n/a	n/a
12_Characters_2_Lines	12	2	0x00	0x40	n/a	n/a
16_Characters_2_Lines	16	2	0x00	0x40	n/a	n/a
20_Characters_2_Lines	20	2	0x00	0x40	n/a	n/a
24_Characters_2_Lines	24	2	0x00	0x40	n/a	n/a
40_Characters_2_Lines	40	2	0x00	0x40	n/a	n/a
16_Characters_4_Lines	16	4	0x00	0x40	0x10	0x50
20_Characters_4_Lines	20	4	0x00	0x40	0x14	0x54	Note DDRAM addresses
20_Characters_4_Lines_KS0073	20	4	0x00	0x20	0x40	0x60	Note DDRAM addresses
27_Characters_4_Lines_2_EN	27	4	0x00	0x40	0x00	0x40	Two Enable-Pins/Controllers
40_Characters_4_Lines_2_EN	40	4	0x00	0x40	0x00	0x40	Two Enable-Pins/Controllers

Note: The HD44780 module drivers supports alphanumeric character LCDs only. Ethersex also has limited support for some graphical displays. Have a look at the LC-Display configuration.

Configuration

 ...
 │ │          Network --->
 │ │          I/O ---> 
 ...
 │ │              ADC / DAC  --->                                                                
 │ │              LCD Displays  --->
 ...
 │ │                  [*] HD44780 module driver (Character-LCD)  --->
 │ │                  [-] HR20-style LCD Display
 ...
 │ │                      (16_Characters_2_Lines) LCD size/type
 │ │                      (HD44780_Compat) LCD controller type
 │ │                      (None) LCD charset conversion
 │ │                      (I2C) Connection type
 │ │                      (PCF8574) I2C Port Expander
 │ │                      [*] Readback support
 │ │                      [*] Backlight support
 │ │                      [*] Backlight on at power-on
 │ │                      [*] Invert Backlight switch

Configuration options:

LCD size/type

Select one of the defined display sizes and address configurations shown in the table above.

Although it is technically possible to connect more than one display, the HD44780 module supports only one LC-Display at a time.

LCD controller type

Select LCD controller circuit:

• HD44780_Compat - most controllers are compatible to Hitachis HD44780
• KS0066U - Samsungs KS0066U requires a different init routine

Almost all controllers for alphanumeric character LCDs are more or less HD44780-compatible at least at the feature- and function- level required by e6.

If in doubt, choose HD44780_Compat.

LCD charset conversion

Select charset conversion used while writing to the lcd:

• None - use no charset conversion at all (safes program mem)
• HD44780_Compat - map characters from ISO8859-1 to the original HD44780 charset

Allmost all controllers use their own non-ISO-compatible charset, varying between manufacturers, rom versions, etc. that provides characters from western languages as well as japanese, chinese and graphical glyphs.

Charset conversion might become useful if you have to display messages and texts from external resources that uses standard encodings for their charset like ISO8859-1.

Note: Charset conversion uses a lookup table and requires about 272 byte program memory (flash rom).

Connection type

Select the connection type for the LCD:

• Direct - direct connection using avr io-pins
• I2C - uses sub-selection of I2C port expander
• SER_LCD(74hct164) - serial connection using HCT164 shift register
• 2WIRE(74hct4094) - serial connection using HCT4094 shift register

See section #Pinning below for further explanations.

I2C Port Expander

Select I2C Port Expander to use:

• PCF8574 - use PCF8574x as I2C port expander
• MCP23017 - use MCP23017 as I2C port expander

Note: automatically enables I2C_MASTER_SUPPORT and I2C_PCF8574X_SUPPORT resp. I2C_MCP23017_SUPPORT when selected.

Note: Selection is only valid when I2C was selected under Connection type.

See section #Pinning below for further explanations.

Readback support

Enable support for bi-directional lcd bus to read LCDs busy flag. Supported by direct and I2C connection only.

You definitly should use a readback capable hardware and enable this feature, saves lots of delays.

Backlight support

Backlight support for LCDs based on the HD44780 controller.

Enable backlight on/off control via API and ECMD.

Backlight on at power-on

Switch on backlight at power-on/reset.

Invert Backlight switch

Invert backlight logic for low active backlight circuits e.g. found on Pollin AVR NET-IO Add-on.

Pinning

Direct

The following example maps the LCD pins to AVR port pins found on the 25 pin Sub-D connector of the Pollin AVR Net-IO board:

dnl Direct connection example
dnl map LCD pins to Pollin AVR Net-IO
dnl 25 pin extension port
ifdef(`conf_HD44780', `
  pin(HD44780_RS, PC4)
  pin(HD44780_RW, PC3)
  pin(HD44780_EN1, PC2)
  dnl pin(HD44780_EN2, PC5)
  pin(HD44780_D4, PA0)
  pin(HD44780_D5, PA1)
  pin(HD44780_D6, PA2)
  pin(HD44780_D7, PA3)
')

ifdef(`conf_HD44780_BACKLIGHT', `
  pin(HD44780_BL, PC6, OUTPUT)
')

I2C

/*
 * HD44780-Display über PCF8574 ansteuern.
 * Belegung Pollin Add-On-Board:
 *
 * Pin PCF8574 Pin am LCD
 * 4 (P0) -> 11 (DB4)
 * 5 (P1) -> 12 (DB5)
 * 6 (P2) -> 13 (DB6)
 * 7 (P3) -> 14 (DB7)
 * 9 (P4) -> 4 (RS)
 * 10 (P5) -> 5 (R/W) nicht benutzt !
 * 11 (P6) -> 6 (EN)
 * 12 (P7) -> 15 (Beleuchtung)
 *
 * Die LCD-Beleuchtung an Pin 12 wird über einen
 * PNP-Transistor geschaltet.
 * Beleuchtung an: Bit 7=0
 * Beleuchtung aus: Bit 7=1
 * Die Address-Eingänge A0 bis A2 des PCF8574 liegen alle auf GND.
 * Die Basis-Addresse des Chips ist daher immer 0x20.
 */

Pinning:

ifelse(value_HD44780_CONNECTION,`HD44780_I2CSUPPORT',`dnl
  ifelse(value_HD44780_I2C_PORTEXP,`HD44780_I2C_PCF8574',
  `ifdef(`conf_HD44780_MULTIEN',
    `dnl
       dnl HD44780_PCF8574x_MULTI_MAPPING(ADR, RS, RW, EN1, EN2, DB4, DB5, DB6, DB7)
       HD44780_PCF8574x_MULTI_MAPPING(0x20, 4, 5, 6, 7, 0, 1, 2, 3)',
    `dnl
       dnl HD44780_PCF8574x_MAPPING(ADR, RS, RW, EN, DB4, DB5, DB6, DB7, BL)
       HD44780_PCF8574x_MAPPING(0x20, 4, 5, 6, 0, 1, 2, 3, 7)')',
  value_HD44780_I2C_PORTEXP,`HD44780_I2C_MCP23017',
  `ifdef(`conf_HD44780_MULTIEN',
    `dnl
       dnl HD44780_MCP23017_MULTI_MAPPING(ADR, PORT, RS, RW, EN1, EN2, DB4, DB5, DB6, DB7)
       HD44780_MCP23017_MULTI_MAPPING(0x24, B, 4, 5, 6, 7, 0, 1, 2, 3)
       HD44780_MCP23017_MULTI_MAPPING_BL(0x24, A, 7)',
    `dnl
       dnl HD44780_MCP23017_MAPPING(ADR, RS, RW, EN, DB4, DB5, DB6, DB7, BL)
       HD44780_MCP23017_MAPPING(0x24, B, 4, 5, 6, 0, 1, 2, 3, 7)')'
  )dnl
')dnl