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Forum : Digole Serial Display :

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trouble with time to write 5 characters to screen using downloaded fonts

Hi all,

Interesting problem when writing 5 characters to the screen.  I have downloaded courB18r [3001] to font space 200, and also have courB24r [4775] to font spaces 201-202.

my program sends 5 characters to the LCD every 100ms via the UART (115200 Baud).

When using font 200 (courB18r [3001]), all the characters display nicely, and very fast.

When using font 201(courB24r [4775]),  it seems to take about 200 to 300mS for 5 characters to display. This means I can only see every third character that was sent displayed.

Is it normal to take so much time when using fonts that take up 2 font spaces in flash?

 

Thanks,

Ed

RE:trouble with time to write 5 characters to screen using downloaded fonts

It probably has data structure problem in your font courB24r [4775] saved to display.

The most possible problem was the font's data not downloaded to display moudle completely, so, add delay after each 64B of font data sent, also slow down the speed on communication when downloading font data. too high speed to data received will cause the internal of 2048B buffer overflow.

 

RE:trouble with time to write 5 characters ...Update....

Victor,

I changed the "write delay" variable from 100 to 300 in the DigoleSerial.H file.

#else   //if writing to internal flash
//#define _WRITE_DELAY 100
#define _WRITE_DELAY 300

Uploading a font takes longer now.

All the fonts I have loaded display very well, but it still takes 200 to 300 milli Seconds to display four characters when using a font that is larger than 3584Bytes.

Fonts that are less than 3584Bytes update to the screen very quickly.

I have tried all of these fonts, they all will display, but have the timing problem (note that each is larger than 3584Bytes and use two "user font" areas in flash);

courB24r[4775]

helvB24r[5214]

ncenB24r[5937]

fub25r[5936]

This really seems to be some sort of page boundary issue in flash.  You can see it for yourself if you write a count-down timer with 1/10 second resoulution.  Use "tens of seconds, seconds, a period, and Tenths of a second".  Send the four byte countdown (TT) to the display prefaced with the proper "SF" and "ETP" every 100mSec.  If you use a built in font or a user font, that is less than 3584Bytes, your tenths of seconds should speed by.  If you use a user font that is over 3584Bytes, you will see your countdown start skipping tenths of a second digits.

Let me know if you have any other ideas to try.

Thanks,

Ed

 

 

RE:trouble with time to write 5 characters...download speed

Victor,

 

I forgot to mention.  I use 9600 baud to upload fonts to display

 

Ed

RE:trouble with time to write 5 characters to screen using downloaded fonts

 Which version of the firmware are you using? While I haven't noticed issues with fonts greater than 3582 bytes, I do have a welcome startup command set that spans the first 2K plus user font 200. There are versions of the firmware that do some bad things because of bugs when flashing user fonts into flash memory (i.e. clearing 64 bytes at a time, even is that block size is outside of that specific user fonts 3582 byte space, etc.)

If you have that large font use 200 and 201 you get the same slowness when printing?

RE:trouble with time to write 5 characters to screen using downloaded fonts

I am using V42B.

 

I went back and loaded a large font across 200-201 and it worked.  So much faster now.  Not perfect, but quite usable.

Thank you for looking at it.

Ed

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