I2C PCF8574 HD44780 Tutorial

All things relating to OLED Screen(s)
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BI1IZF
Posts: 2
Joined: Sat Feb 27, 2021 5:22 pm

I2C PCF8574 HD44780 Tutorial

Post by BI1IZF »

Open Source
sch,pcb,gerber file-->https://gitee.com/fiftyhz/BI1IZF/tree/m ... 74_HD44780
you can DIY PCB,Of course you can also buy the PCF8574 module. :D
  • 1. Connect PCF8574 to Raspberry,VCC to VCC, SDA to SDA, SCL to SCL, GND to GND.The backlight cannot be controlled by PCF8574,
    it needs to be connected separately,Please check the schematic.
  • 2. Determine the I2C address,use

    Code: Select all

    i2cdetect -y 1
  • 3. set MMDVM Display Type is HD44780 and save
  • 4. check configuration-Expert-MMDVMHost-HD44780 config,if you use pwm,change pwn 1,Apply Changes
this is my config
Image
-----------------------------------------------------------------This is the dividing line---------------------------------------------------------
  • Normally, the screen will display, if there is no display, try to adjust the screen contrast
  • If you buy a PCF8574 module, you must check the connection between the module and HD44780. It must be the following, is very important
Image
  • If you use PWM ,connection RPI Pin 32(GPIO pin 12,Wiring Pi pin 26) to HD44780 Pin15,Pin16 to GND,RPI output current can drive the backlight, of course you can use a triode
Image
If you do not use PCF8574, you also need to compile the file->https://github.com/g4klx/MMDVMHost/blob ... ME.HD44780
I can answer all questions about HD44780

73
BI1IZF
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Last edited by BI1IZF on Mon Nov 15, 2021 2:39 am, edited 2 times in total.
BI1IZF
Posts: 2
Joined: Sat Feb 27, 2021 5:22 pm

Re: I2C PCF8574 HD44780 Tutorial

Post by BI1IZF »

KE7FNS wrote: Wed Sep 08, 2021 5:05 pm
BI1IZF wrote: Wed Sep 08, 2021 2:11 pm
i2c is already enabled in Pi-Star.
BI1IZF wrote: Wed Sep 08, 2021 2:11 pm sudo make Makefile.Pi.PCF8574
You shouldn't have to build a custom MMDVMHost, Pi-Star is already configured to work with a HD44780.
Thank you for your answer
I saw in the G4KLX document that it needs to be compiled, but it is not needed, which makes the operation easier。 :lol:
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