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JohnDoneth / hd44780-driver

Implementation of the embedded-hal traits for the HD44780.
MIT License
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Implement two-dimensional cursor addresses. #38

Closed rene0 closed 2 years ago

rene0 commented 2 years ago

Currently the set_cursor_pos() method takes a one-dimensional address to move the cursor. The article at [1] shows how to calculate this address from an (x,y) coordinate pair for various display sizes. Note that the example

set_cursor_pos(40, &mut delay); // move to line 2

only works by accident, because "The LCD controller automatically accounts for the gap in addresses and after storing an ASCII code in address 27h it puts the next code in address 40h. Similarly it increments from address 67h back to 00h." ([1], just before "40x2 LCD")

An implementation of this calculation is done in [2] (copied from [3]), which I tested on a 20x4 display. Perhaps the panic() does not make sense for the library, and perhaps the constructors could take the number of columns and rows into account?

[1] https://web.alfredstate.edu/faculty/weimandn/lcd/lcd_addressing/lcd_addressing_index.html [2] https://github.com/rene0/rp-rs-radio-clock/blob/hardware-tests/test-display/src/main.rs#L29 [3] https://github.com/dhylands/python_lcd/blob/master/lcd/lcd_api.py#L122

rene0 commented 2 years ago

[2] has been replaced by https://github.com/rene0/rp-rs-radio-clock/blob/1d7ee96977c4f12cbbed9366fcada87832c708b6/hd44780_helpers/src/lib.rs#L18 , I moved that function into its own crate.

chevdor commented 2 years ago

@rene0 thank you for reporting this issue and researching on the topic. You will find your findings implemented in PR #40.

chevdor commented 2 years ago

Closed by #40

rene0 commented 2 years ago

Thanks for implementing this, i know I just gave a freestyle suggestions somewhat on purpose. The set_cursor_xy() function is now implemented in rene0/rp-rs-radio-clock, just not in the main program because that is published on crates.io which forbids external references.