From 6cb03a836110e79d32026ce1e8c5710b918fa2ef Mon Sep 17 00:00:00 2001
From: Lauchmelder23 <robert.trololo@gmail.com>
Date: Fri, 20 Nov 2020 14:44:34 +0000
Subject: [PATCH] Added support for custom characters

---
 README.md         | 13 +++++++++++++
 example/example.c |  8 +++++++-
 raspberrylcd.c    | 12 ++++++++++++
 raspberrylcd.h    |  5 ++++-
 4 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 46c46f3..edf1d0c 100644
--- a/README.md
+++ b/README.md
@@ -114,6 +114,19 @@ This function sends a variable number of characters to the screen. Use `sendText
 
 ***
 
+```c
+void loadCustomChar(LCDScreen* screen, uint8_t cgram_addr, ...);
+```
+This function writes a custom character into the CGRAM of the LCD screen. `cgram_addr` can be any number from `0x0` to `0xF`. Hence you can have up to 16 custom characters at once in memory. 
+
+After the address the function expects 8 bytes of character data. The lower 5 bits encode the pixel data, where 0 stands for black and 1 for white.
+
+After loading a character you can write it by using the CGRAM address as a character byte for the `sendData` function (e.g. `sendData(&screen, 0)` will send the character at CGRAM address `0x0`).
+
+WARNING: Writing to CGRAM moves the cursor, so keep that in mind when you try to write characters to memory.
+
+***
+
 ```c
 void clearScreen(LCDScreen* screen);
 ```
diff --git a/example/example.c b/example/example.c
index 8ec1073..8827d0d 100644
--- a/example/example.c
+++ b/example/example.c
@@ -6,7 +6,13 @@ int main(void)
     configurePins(&screen, 7, 9, 8, 0, 0, 0, 0, 21, 22, 23, 24);
 
     initScreen(&screen, HALF_BYTE_INTERFACE, TWO_LINES, FONT_5x7, CURSOR_ON | CURSOR_BLINK, LEFT_TO_RIGHT);
-    sendText(&screen, "ゴチソウサマデシタ");
+    
+    loadCustomChar(&screen, 0, 0b00000, 0b00000, 0b01010, 0b00000, 0b10001, 0b01110, 0b00000, 0b00000);
+
+    returnCursor(&screen);
+    sendChars(&screen, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
+    setCursor(&screen, 0, 1);
+    sendChars(&screen, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
     resetPins(&screen);
 
     return 0;
diff --git a/raspberrylcd.c b/raspberrylcd.c
index 5a23983..73be346 100644
--- a/raspberrylcd.c
+++ b/raspberrylcd.c
@@ -244,3 +244,15 @@ void sendChars(LCDScreen* screen, size_t len, ...)
 
     va_end(args);
 }
+
+void loadCustomChar(LCDScreen* screen, uint8_t cgram_addr, ...)
+{
+    va_list args;
+    va_start(args, cgram_addr);
+
+    sendCommand(screen, CGRAM_AD_SET | (cgram_addr << 3));
+    for(int i = 0; i < 8; i++)
+        sendData(screen, va_arg(args, int));
+
+    va_end(args);
+}
\ No newline at end of file
diff --git a/raspberrylcd.h b/raspberrylcd.h
index 6f2d8d5..2c72565 100644
--- a/raspberrylcd.h
+++ b/raspberrylcd.h
@@ -131,6 +131,7 @@
 #define CURSOR                          0b11111111
 
 #include <stdint.h>
+#include <stdarg.h>
 
 extern void waitMs(uint32_t ms);
 
@@ -151,8 +152,10 @@ extern void sendData(LCDScreen* screen, uint8_t data);
 extern void sendText(LCDScreen* screen, const char* text);
 extern void sendChars(LCDScreen* screen, unsigned int len, ...);
 
+extern void loadCustomChar(LCDScreen* screen, uint8_t cgram_addr, ...);
+
 #define clearScreen(screen)                                                     sendCommand(screen, SCREEN_CLEAR)
-#define returnCursor(screen)                                                    sendCommand(screen, CURSOR_RETURN)
+#define returnCursor(screen)                                                    sendCommand(screen, CURSOR_RETURN); 
 #define setWritingDirection(screen, direction)                                  sendCommand(screen, INPUT_SET | direction)
 #define setDisplaySettings(screen, display, cursor_shown, cursor_behaviour)     sendCommand(screen, DISPLAY_SWITCH | display | cursor_shown | cursor_behaviour)
 #define shiftCursor(screen, direction)                                          sendCommand(screen, SHIFT | CURSOR_SHIFT | direction)