From ed0b5d4c6f4c363e67bb4ee246f428adcbf37077 Mon Sep 17 00:00:00 2001
From: Akos Kiss <akiss@inf.u-szeged.hu>
Date: Tue, 13 Oct 2020 23:38:43 +0200
Subject: [PATCH] Handle the difference between 1 and 2-line displays in
HD44780
If HD44780 is configured to have a single line of display, AC can
be in the range of 0x00..0x00+79, while with two lines, it can be
in the ranges 0x00..0x00+39 and 0x40..0x40+39.
---
examples/parts/hd44780.c | 45 +++++++++++++++++++++++++++-------------
1 file changed, 31 insertions(+), 14 deletions(-)
diff --git a/examples/parts/hd44780.c b/examples/parts/hd44780.c
index a2d0177..1d0da5d 100644
--- a/examples/parts/hd44780.c
+++ b/examples/parts/hd44780.c
@@ -88,10 +88,15 @@ hd44780_kick_cursor(
if (hd44780_get_flag(b, HD44780_FLAG_I_D)) { // incrementing
if (b->cursor < 0x80) { // cursor in DDRAM
b->cursor++;
- if (b->cursor >= 0x00 + 40 && b->cursor < 0x40) // jump from end of first memory segment to the start of the second segment
- b->cursor = 0x40;
- else if (b->cursor >= 0x40 + 40) // wrap around from the end of the second memory segment to the start of the first segment
- b->cursor = 0x00;
+ if (hd44780_get_flag(b, HD44780_FLAG_N)) { // 2-line display
+ if (b->cursor >= 0x00 + 40 && b->cursor < 0x40) // jump from end of first memory segment to the start of the second segment
+ b->cursor = 0x40;
+ else if (b->cursor >= 0x40 + 40) // wrap around from the end of the second memory segment to the start of the first segment
+ b->cursor = 0x00;
+ } else { // 1-line display
+ if (b->cursor >= 0x00 + 80) // wrap around from the end of the memory to the start
+ b->cursor = 0x00;
+ }
} else { // cursor in CGRAM
if (b->cursor == 0x80 + 0x3f) // wrap around in CGRAM
b->cursor = 0x80;
@@ -100,12 +105,19 @@ hd44780_kick_cursor(
}
} else { // decrementing
if (b->cursor < 0x80) { // cursor in DDRAM
- if (b->cursor == 0x40) // fall back from the start of the second memory segment to the end of the first segment
- b->cursor = 0x00 + 39;
- else if (b->cursor == 0x00) // wrap around from the start of the first memory segment to the end of the second segment
- b->cursor = 0x40 + 39;
- else
- b->cursor--;
+ if (hd44780_get_flag(b, HD44780_FLAG_N)) { // 2-line display
+ if (b->cursor == 0x40) // fall back from the start of the second memory segment to the end of the first segment
+ b->cursor = 0x00 + 39;
+ else if (b->cursor == 0x00) // wrap around from the start of the first memory segment to the end of the second segment
+ b->cursor = 0x40 + 39;
+ else
+ b->cursor--;
+ } else { // 1-line display
+ if (b->cursor == 0x00) // wrap around from the start of the memory to the end
+ b->cursor = 0x00 + 79;
+ else
+ b->cursor--;
+ }
} else { // cursor in CGRAM
if (b->cursor == 0x80) // wrap around in CGRAM
b->cursor = 0x80 + 0x3f;
@@ -155,10 +167,15 @@ hd44780_write_command(
// Set DDRAM address
case 7: // 1 ADD ADD ADD ADD ADD ADD ADD
b->cursor = b->datapins & 0x7f;
- if (b->cursor >= 0x00 + 40 && b->cursor < 0x40) // illegal address after the first memory segment -> set cursor to start of second segment
- b->cursor = 0x40;
- else if (b->cursor >= 0x40 + 40) // illegal address after the second memory segment -> set cursor to start of first segment
- b->cursor = 0x00;
+ if (hd44780_get_flag(b, HD44780_FLAG_N)) { // 2-line display
+ if (b->cursor >= 0x00 + 40 && b->cursor < 0x40) // illegal address after the first memory segment -> set cursor to start of second segment
+ b->cursor = 0x40;
+ else if (b->cursor >= 0x40 + 40) // illegal address after the second memory segment -> set cursor to start of first segment
+ b->cursor = 0x00;
+ } else { // 1-line display
+ if (b->cursor >= 0x00 + 80) // illegal address after valid memory -> set cursor to start
+ b->cursor = 0x00;
+ }
break;
// Set CGRAM address
case 6: // 0 1 ADD ADD ADD ADD ADD ADD ADD
--
2.39.5