sixerdoodle / graphiclcd_serial_backpack

Modification of SparkFun GraphicLCD_Serial_Backpack

GraphicLCD_Serial_Backpack

Modification of SparkFun GraphicLCD_Serial_Backpack 10/4/2018

Multiple modifications and bug-fixes from the original SparkFun Firmware

0. Updated code to compile under Atmel Studio 6.2

   PROGMEM changed from old version of Atmel studio, had to add "const" to the static char statement.

1. Serial buffer overflow handing

   With a fast enough processor (Particle Photon in my case) it was possible to overrun the serial buffer. Firmware now uses the TX pin as a overflow flag. TX pin is set HIGH when the serial buffer gets 1/2 full. Once the buffer is empty the TX pin goes LOW.

2. Serial Buffer modification

   Variable bufferSize was uint8_t and BUF_DEPTH was 256, so at 'full' buffer bufferSize would be 256 which doesn't fit in 8 bits. Changed BUF_DEPTH to 255 to facilitate uint8_t size pointers for ALL serial buffer access. This fixes the full buffer problem AND speeds up buffer access as it's 8 bit math rather than 16 bit

3. Bugfix writedata across chip boundary

   on the Small display, when writedata crossed the 64 byte boundary into the 2nd chip the in-chip X (column) doesn't auto-reset to 0 and instead picks up wherever the 2nd chip X last was. Added code in writedate to force chip 2's X to 0 when X crosses 63->64 byte boundary

4. Fast Text write

   Small Display only (someone else write the large display). Modified the draw text algorithm to optimize when drawing text on a full row boundaries (ie Y = 0,8,16, etc) Much, much faster as full row only does write rather than read/modify/write

5. Fast area fill

   Small Display only. Modified the area fill algorithm to optimize for filling full rows a byte at a time when possible.

6. Implement Serial Test function code 0x01

   Byte following the 0x01 is the 'target byte'. Host should send continuous stream of 'target bytes' after that. If the received byte does not match the target byte then an X is written to the LCD. Over an extended test time, the number of X's displayed indicates the number of transmission errors.

7. Implemented debug bits

   if DEBUG_IO is defined in glcdbp.h then use PB4/5 as information bits. Look at ks0108b.c WaitReady routine as example. Turn PB5 HIGH when entering the routine and LOW when exiting the routine. This is only as example, use to delineate routines when you do your own firmware development

8. Implemented Trigger function code 0x08

   use in conjunction with PB4/5 debug information bits above. Function 0x08 causes PB5 to toggle HIGH/LOW for use in signal capture when troubleshooting firmware routes.

graphiclcd_serial_backpack's Issues

Changing PORTC pins

Great job!!. I have designed Sparkfun GraphicLCD_Serial_Backpack PCB with few modification in PORTC (commands) to connect 64x128 GLCD with TS12864A-2 chipset (KS0108) as listed below but after change the pins in the io_support.h, LCD is showing some changes in brightness during demo() and noting is showing even with change in the POT 10K.
#define EN 0 // PC0 => PC2
#define RS 1 // PC1 => PC0
#define R_W 2 // PC2 => PC1
#define RESET 3 // PC3
#define CS1 4 // PC4 => PC5
#define CS2 5 // PC5 => PC4