85 lines
2.9 KiB
Plaintext
85 lines
2.9 KiB
Plaintext
- HD44780 LCD SUPPORT -
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Support for the HD44780 LCD is via the wiringPi library available at
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http://wiringpi.com/download-and-install/ which must be installed in all cases.
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The HD44780 in 4-bit mode is probably the most common connection method and
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wiring details can be found at http://wiringpi.com/dev-lib/lcd-library/
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The setup that is commonly used for MMDVM is the 4-bit connection that is also
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documented within wiringPi. The HD44780 displays have a standardized 16-pin
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connector (14 pins if without backlight). The pin numbers on HD44780 refer to
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this standard numbering.
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The pin numbers on Raspberry Pi side are the physical pin numbers of the GPIO
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pin header, in brackets the wiringPi pin number as these are referred to in the
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MMDVM.ini file.
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The wiring ist as follows:
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HD44780 pin Raspberry Pi GPIO
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GND 1 -------- 6 GND
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VCC 2 -------- 2 +5V
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V0 3 -------- Trimmer between +5V and GND for contrast
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RS 4 -------- 26 CE1 (11)
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RW 5 -------- 6 GND
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E 6 -------- 24 CE0 (10)
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D0 7
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D1 8
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D2 9
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D3 10
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D4 11 -------- 11 GPIO0 (0)
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D5 12 -------- 12 GPIO1 (1)
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D6 13 -------- 13 GPIO2 (2)
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D7 14 -------- 15 GPIO3 (3)
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VCC 15 -------- 2 +5V
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GND 16 -------- 6 GND
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The relevant part in the MMDVM.ini is like outlined below.
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[HD44780]
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Rows=4
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Columns=20
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# For basic HD44780 displays (4-bit connection)
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# rs, strb, d0, d1, d2, d3
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Pins=11,10,0,1,2,3
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To compile MMDVMHost with support for the HD44780 use the following commands.
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# make clean
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# make -f Makefile.Pi.HD44780
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Other HD44780 variations exist that connect via I2C. Support is also via
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wiringPi, but to compile for each I2C device requires a different Makefile
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depending on the IC attached to the LCD.
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- ADAFRUIT RGB LCD SHIELD -
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The Adafruit RGB LCD Shield is available from https://www.adafruit.com/product/714
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I2C is via the MCP23017 IC and is enabled with Makefile.Pi.Adafruit. The
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I2C device address in MMDVM.ini should be set to 0x20.
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- PCF8574 IC -
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HD44780 LCDs connected via a PCF8574 Remote 8-Bit I/O Expander are available on
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eBay for very little money! This IC uses Makefile.Pi.PCF8574 and the I2C
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device address should be set to 0x27.
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- BEWARE -
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The I2C device address can be manually configured on some devices!
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- CHECK YOUR ACTUAL DEVICE ADDRESS -
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More information on configuring and using I2C on the RPi including how to probe
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the I2C bus for device addresses can be found at
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https://learn.sparkfun.com/tutorials/raspberry-pi-spi-and-i2c-tutorial#i2c-on-pi
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- PWM BACKLIGHT CONTROL -
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Whilst connected in 4-bit mode or via the PCF8574 IC, the LED backlight can be
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wired for control via PWM. Connect the backlight +ve pin to any spare GPIO pin
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and configure MMDVM.ini as appropriate. By default, wiringPi pin 21 is
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configured.
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