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Author Topic: 4 bit LCD library and Hitachi HD44780 compatible display  (Read 3441 times)
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Is jumper link J2 soldered or open?

Don
it looks like it is open
OK - That means that pin 5 functions the same way as the Hitachi chip and to work correctly with the LiquidCrystal library it must be connected to GND.

It looks like pin 3 is a /Reset pin so you really should connect it to +5V, preferably via a pull-up resistor.


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there are also other posts on the forum that i read where people are using the arduino library for the vfd. it is an lcd compatible vfd
Your results seem to indicate that the instruction set is the same as (or very similar to) the one for the HD44780 but at least some of the timing is not compatible.  It would help if you could dig up a full data sheet.

Don
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Is jumper link J2 soldered or open?

Don
it looks like it is open
OK - That means that pin 5 functions the same way as the Hitachi chip and to work correctly with the LiquidCrystal library it must be connected to GND.

It looks like pin 3 is a /Reset pin so you really should connect it to +5V, preferably via a pull-up resistor.


Quote
there are also other posts on the forum that i read where people are using the arduino library for the vfd. it is an lcd compatible vfd
Your results seem to indicate that the instruction set is the same as (or very similar to) the one for the HD44780 but at least some of the timing is not compatible.  It would help if you could dig up a full data sheet.

Don

here is another datasheet i found

http://www.ko4bb.com/Manuals/09)_Misc_Test_Equipment/Noritake/Noritake-HD44780.pdf
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I found that one last night.  It is not a data sheet it is an application note which is valuable, but not the same.  If you look at the last page you will find some significant timing differences mentioned which may not be satisfied by the LiquidCrystal (or any other LCD) library.  The difference in the Address/data hold time is significant when you consider that the processor can do 11 typical instructions during that 700nS.

Of course you have to speculate on the accuracy of all of the information after you read their description on the previous line concerning what happens on a regular LCD when you write more than 64 (actually 80) bytes of data.


Don
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i could not find another datasheet, but my work around of issuing the lcd.setCursor command twice everytime i want to use it works flawlessly
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i justed wanted to update this

Since I changed to the New Liquidcrystal library i no longer have this issue

Code:
https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads

i have also in the meantime switched to using I2C and it still works flawlessly
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Thanks for the update.

Don
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