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Forum Index : Microcontroller and PC projects : Issue with "DEVICE LCD CMD" and "DEVICE LCD DATA"

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stef123
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Joined: 25/09/2024
Location: United Kingdom
Posts: 25
Posted: 11:44pm 03 Nov 2024
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Hi,

i´m trying to implement a custom Charset for my HD44780-Display, but found a problem.

According to my Logic Analyzer, after "DEVICE LCD CMD", issuing "DEVICE LCD DATA", the RS Line is still being held low (CMD), but it has to be high (DATA).

Tested V5.08, aswell V6.00.

My fault, or a bug?

Best regards
Stef
Edited 2024-11-04 09:45 by stef123
 
stef123
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Joined: 25/09/2024
Location: United Kingdom
Posts: 25
Posted: 03:14am 04 Nov 2024
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Working Solution: External.c, line 2322.

"    LCD_Byte(j, toupper(*cmdline) == 'D', 0);"

to

"    LCD_Byte(j, toupper(*p) == 'A', 0);"

Idk if *cmdline or 'D' was the issue. toupper(*cmdline) =='A' didn´t resolve the problem either. But since i suspect that tupper has to be true (1) in case of "DATA", because it controls eventually the RS Line and 'D' can be found several times in the command string (eg "DEVICE LCD CMD"), i´ve chosen 'A' (=if found, RS=1, if not, RS=0)

Maybe not perfect, but i have not much knowledge about C++ behaviour at all. At least it works.
Edited 2024-11-04 13:15 by stef123
 
disco4now

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Joined: 18/12/2014
Location: Australia
Posts: 906
Posted: 04:53am 04 Nov 2024
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I think the line should be

LCD_Byte(j, toupper(*lcd) == 'D', 0);


lcd is set to point to the first character of DATA or CMD a couple of line above
i.e.

} else if((p = checkstring(lcd, (unsigned char *)"CMD")) || (p = checkstring(lcd, (unsigned char *)"DATA"))) { // send a command or data

Latest F4 Latest H7
 
stef123
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Joined: 25/09/2024
Location: United Kingdom
Posts: 25
Posted: 01:15pm 04 Nov 2024
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Thanks !

So correct me if i´m wrong - i´m not into C++ programming at all, i do more Assembler and Basic - if you deliver *cmdline to toupper (idk if it contains the entire command string, i think so), you will always run into a toupper-Flag that is set because it finds the "D" of "Device". That would mean that the Flag/RS line would be always high, but that isn´t the case.



But if *cmdline contains the string "LCD" without "DEVICE" , toupper runs into a Flag that is not being set (=RS-Line low) (wrong: Flag=1, RS=High) and doesn´t care about the following "CMD" or "DATA", because it already found the first occurance of "D" in "LCD".

What i don´t understand is why *cmdline wouldn´t work together (better: doesn´t give the correct result) for example with toupper "A", but *p with "A". If "DATA" is the key to set the Flag, toupper would find in  *cmdline the occurance "A" in "Data" which would be flag=1 = RS=1.

Thats the reason why i have chosen "A" (could have been "T" aswell), because "D" occurs in "CMD" aswell in "DATA".

As said, idk the contents of *cmdline.
Edited 2024-11-04 23:37 by stef123
 
matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 9201
Posted: 01:27pm 04 Nov 2024
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Please try V6.00.00RC14 and let me know if it works. NB: in RC14 you can use the LCD command without the DEVICE prefix
 
stef123
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Joined: 25/09/2024
Location: United Kingdom
Posts: 25
Posted: 01:47pm 04 Nov 2024
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Hi Peter,

yup, RC14 works as expected.

Thank you!
 
JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 3820
Posted: 01:56pm 04 Nov 2024
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deleted - fixed by Peter et al I think

John
Edited 2024-11-04 23:56 by JohnS
 
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