HardFaultException

if the hard fault occurs within HD44780_PowerUpInit(); then it's pretty difficult to guess.

If the hard fault occurs when you call HD44780_PowerUpInit(); then check the address of HD44780_PowerUpInit either by looking at the assembler listing or by casting it to a u32 and outputting. You could also check the map file. Check if this address is within a valid region of memory.

1. check the ISRs.

https://my.st.com/public/STe2ecommunities/mcu/Lists/ARM%20CortexM3%20STM32/DispForm.aspx?ID=2266