fix ELW0901AA issues #2135

[iggymayer]

fix issues #2135
I2C & SPI test passed
Notice: If using I2C, the I2C buffer size needs to be increased: Wire.setBufferSize(600);

[olikraus]

What is the issue with the buffer size? The problem is, that this is a restriction of the Arduino framework.
U8g2 architecture tries to deal with the limited buffer.

[olikraus]

where exactly is the i2c buffer size increased?

[iggymayer]

when using the hardware I2C interface, several bright dots appear on one side of the screen (not damaged). The data being sent exceeds the default size of the Arduino Wire library's send buffer. Due to my limited abilities, this is the only solution I can think of at the moment.

#include <Arduino.h>
#include <U8g2lib.h>

#ifdef U8X8_HAVE_HW_SPI
#include <SPI.h>
#endif
#ifdef U8X8_HAVE_HW_I2C
#include <Wire.h>
#endif

#define RES_PIN 21
#define HV_EN 1

U8G2_LD7032_128X36_F_HW_I2C u8g2(U8G2_R0, RES_PIN);

void setup(void) 
{
    pinMode(HV_EN, OUTPUT);
    digitalWrite(HV_EN, HIGH);

    Wire.setBufferSize(600);

    u8g2.begin();
    u8g2.setFontPosTop();
}

void loop(void) 
{
    u8g2.clearBuffer();
    u8g2.setFont(u8g2_font_spleen6x12_mf);
    u8g2.drawStr(0,0,"Hello World!");
    u8g2.drawBox(99, 0, 99, 36);
    u8g2.sendBuffer();

    delay(1000);
}

[olikraus]

the u8x8_cad_ld7032_i2c procedure will break this down to smaller blocks, except for the init sequence.
If the init sequence is more than 32 bytes it might be a problem.

u8g2/csrc/u8x8_cad.c

Line 704 in ab9e48b

uint8_t u8x8_cad_ld7032_i2c(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)

[olikraus]

A solution could be to reduce the size of u8x8_d_ld7032_128x36_init_seq.
We could also have two arrays and send both arrays one after the other.

Maybe that is also the reason why the 60x32 never worked for me with I2C

I could also try to update the cad procedure: The buffer could be flushed with every new command. (buffer flush probably is not allowed during arg transmission). Let me create an issue for this.

I think fixing u8x8_cad_ld7032_i2c would be the most compatibe solution from my perspective (provided, that the init sequence is the problem)

[olikraus]

Here is my suggestion: I will try to fix u8x8_cad.c, then we can include your LD7032 code.
issue: #2789

[iggymayer]

Okay, thank you.