Andrew West

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7 years, 9 months ago.

mbed Pin Assignment

I'm trying to connect an HD44780 LCD through a PCF8574T I2C expansion board to a Nucleo-L476RG

I've found the textLCD-enhanced library here (https://developer.mbed.org/users/wim/notebook/textlcd-enhanced/) which seems right for the what I want to do, however, it references mbed pins (see image) and I cant find any information about how the 'mbed pin' numbers relate to the L476RG

Any help appreciated,

Andy /media/uploads/andyowenwest/mbed_pins.png

Have just found this, would this relate to the mbed pins? https://developer.mbed.org/users/mbed_official/code/mbed-dev/file/default/targets/TARGET_STM/TARGET_STM32L4/TARGET_STM32L476xG/TARGET_NUCLEO_L476RG/PinNames.h

posted by Andrew West 03 Mar 2017

1 Answer

Jan Jongboom
7 years, 9 months ago.

Reading the text it says:

Serial connection using mbed I2C bus and a PCF8574/PCF8574A or MCP23008 portexpander

So how I read it you'll need to just wire the PCF8574 up over I2C to the NUCLEO. So connect p8 of the PCF8574 to GND, p16 to 5V, p15 to SDA (D14 on NUCLEO) and p14 to SCL (D15 on NUCLEO).

Accepted Answer

Trying that now, I just dont understand why it references p9, p28, p10 and p27. Its like its referencing a different board but theres nothing in the library documentation that says so

posted by Andrew West 03 Mar 2017

I think it was written with the LPC1768 in mind. It has I2C on p9/p10 and p27/p28.

posted by Jan Jongboom 03 Mar 2017