OLED Initialization - NHD-0420DZW-AB5
I looked at the code supplied by newhaven for 8-bit given at the thread below:
which initializes with
void init(){
E = 0;
Delayms(5);
command(0x30); //0x30
Delayms(100);
command(0x30); //0x30
Delayms(10);
command(0x30); //0x30
Delayms(10);
command(0x38); //func set 8-bit
command(0x10); //cursor/disp shift left
command(0x0c); //Display ON
command(0x06); //Entry mode set
}
This does not match what the datasheet says on pg. 20 which would be something like shown below but I put a delayms(10) at the end of the command() function instead of checking Busy flag.
void init(){
E = 0;
Delayms(5);
command(0x38); //func set 8-bit
Delayms(100);
command(0x08); //Display OFF
command(0x01); //Clear display
command(0x06); //Entry mode set
command(0x02); //HOME
command(0x0C); //Display ON
}
Neither of these types of initialization work. Do we need the three dummy function sets at the beginning (0x30)? It just seems like the datasheet almost gets you there, but leaves out some required commands for initalization and timing. For example, the datasheet says power on and wait >1ms although your example code above shows it waiting 100 ms. It's really easy to get an HD44780 to work, but this has been extremely challenging. Any help appreciated and once we figure out how to initialize the display properly, then please update the datasheet.
Thanks.
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Can the enable signal go HIGH before the data is put onto the 8 data pins and then bring ENABLE signal LOW?
I am setting EN=1 and RS and R/W to their appropriate value, then putting data on the 8 pins, then bringing Enable low to latch it. Something is not working right though.0 -
Hi Signalflow,
I’m sorry to hear about the trouble you are having with NHD-0420DZW-AB5. Let me help you out with your initialization sequence
Please try the following:
On power up, the display is initilaized as:
1. Display clear
2. Function set:
DL="1": 8-bit interface data
N="0": 1-line display
F="0": 5 x 8 dot character font
3. Power turn off
PWR=”0”
4. Display on/off control: D="0": Display off C="0": Cursor off B="0": Blinking off
5. Entry mode set
I/D="1": Increment by 1
S="0": No shift
6. Cursor/Display shift/Mode / Pwr
S/C=”0”, R/L=”1”: Shifts cursor position to the right
G/C=”0”: Character mode
Pwr=”1”: Internal DCDC power on// 4-Bit initialization sequence
write4bits(0x03); // Put back into 8-bit mode
delayMicroseconds(5000);
if(_oled_ver == OLED_V2) {
write4bits(0x08);
delayMicroseconds(5000);
}
write4bits(0x02); // Put into 4-bit mode
delayMicroseconds(5000);
write4bits(0x02);
delayMicroseconds(5000);
write4bits(0x08);
delayMicroseconds(5000);
command(0x08); // Turn Off
delayMicroseconds(5000);
command(0x01); // Clear Display
delayMicroseconds(5000);
command(0x06); // Set Entry Mode
delayMicroseconds(5000);
command(0x02); // Home Cursor
delayMicroseconds(5000);
command(0x0C); // Turn On - enable cursor & blink
delayMicroseconds(5000);0 -
OK, I seem to have gotten it to initialize properly.
The problem I am having still is that I can write strings such as
LCD_write_string("Test") but if I put spaces in like
"LCD_write_string("Test String") then it gives me erroneous character for the space. Also the display (characters) are dimming. The brightness is oscillating or cycling from the top of each character to the bottom over and over. Is it supposed to do that or maybe it isn't initialized properly?0 -
Nevermind, seems I had a bad connection on Vcc (was low voltage). Once I gave it a good connection the display quit flickering and the erroneous characters went away for spaces.
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Glad to hear you got your display up and running!
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