NHD-C0216CZ-FSW-FBW-3V3 problems

[Felix]

We access a NHD-C0216CZ-FSW-FBW-3V3 over SPI from a FPGA. Because the display does not work I am not sure if I understand the SPI communication correct:

I do it according to the ST7032 datasheet (page 33, 34, 37, 45). And I tried also the commands freom the LCD data sheet page 10.

If I send only one command I have to send only 8 bits? What could be wrong?

Attached is a screenshot of a SPI access (0x0F : Display, cursor and cursor position on)

LCD_DNI ist the RS signal

Felix

[Saurabh_B]

Hi Felix,

Do you have anything tied to the RS pin on the display? (I did not see this in your picture)

If so, have you initialized the display?

[Felix]

There was im timing issue and sometimes there were more than eight SCLK (9 to 12 ). And that caused the problems when writing commands. Now I can use all the commands successful.

But sending data to the display (RAM) does not work correctly: I always send 4 bytes. But the display shows only one or two oft this letters/numbers.

Is there a minimum time between sending each byte/character to the display/RAM?

Felix

[Saurabh_B]

Felix,

Yes there is a minimum execution time for commands sent to the display. You can find the minimum execution on the table in page 6 of the display specification.
Display Specification

[Felix]

Thanks. I solved it with different timings until it worked. Only then I saw the minimum execution time in the table.

Now we have two problems with command:

Return Home 0x02 is not working.

Set DDRAM address to 0x40 (command 0xC0) is also not working. We can't acces the 2nd line of our display

Our initialisation is:

Function Set:       0x39   2 lines ON, double height font OFF, instruction table 1 (frequency/power/follower control)
Internal OSC frequency   0x14   settings for internal osc frequency
Power Control       0x56   
Follower Control    0x6D
Contrast         0x70   contrast set for internal follower mode
Display on       0x0F   Display, Cursor, Cursor  Position ON
Entry Mode       0x06   cursor moves right, DDRAM address increase
Clear Display      0x01   clears display
Function Set:       0x38   2 lines ON, double height font OFF, instruction table 0 (cursor+display shift, CGRAM adr)

After that the first line is working. But we cant access the 2nd line with 0xC0

Felix

[Felix]

Now we have two problems with command:

Return Home 0x02 is not working.

Set DDRAM address to 0x40 (command 0xC0) is also not working. We can't acces the 2nd line of our display

The solution Shaurab suggested by email was to send the wakeup command (Function Set 0x39) more than once.

After sending five wakeup commands both commands are working.

Regards, Felix