issue of RAMPS-FD LCD adapter (with smart controller)

Hi all
I am trying making a ramps-fd lcd adapter ,bobc give us a very nice solution ,in bobc's solution ,the adapter change the logic voltage with 74HC07A .I make some change ,I use 74LS07 and 7407,and then some issue come out .... the lcd not working ...So I try to see what happened ...here is some results .

FOR arduino mega2560 smart controller adapter 2004 LCD working good ,here is the screenshot with saleae logic 1.1.15


As you can see LCDRS LCD4 LCD5 LCD6 LCD7 have normal signal .And LCDE also has normal signal...

Here is LCD with out adapter


LCDE signal is as controller with adapter ...

OK than the issue is coming ....



This is the screenshot that ramps-fd without lcd adapter pls notice the signal .this is the normal signal .



screenshot above is lcd adapter with ic 74LS07 ,the signal of LCDE is not working normally...



adapter with ic 7407 ,the signal of LCDE is not working normally either... signal has some random noise ,so lcd can not tell when should begin to work..

I have check lcd's schematics the signal voltiage is converted by ic 74HC07A ...
SO I wounder that 74HC07 can be changed by 74ls07 or 7407 ???

Edited 1 time(s). Last edit at 03/18/2014 08:35AM by sakunamary.

I would stick to a 74HC or 74AC chip. A 74LS chip running on 5V may not see 3.3V high voltage as "high", whereas a HC/AC chip should.

Quote
Cefiar
I would stick to a 74HC or 74AC chip. A 74LS chip running on 5V may not see 3.3V high voltage as "high", whereas a HC/AC chip should.

SO Cefiar your adapter with IC 74HC07 and working ??? if working good than I change IC. so ,would you let me know ....thanks a lot !

I don't have the adaptor.

I was however involved with bobc on the design of the RAMPS-FD board, and the voltage trigger reason was why we use 74HC or 74AC parts elsewhere on the board (to go from 3.3V to 5V).

OK , I have brought some 74HC07 ,and try later today...

Hi all

I find out what happend of this issue (I guess so ) ....The reason of lcd adapter not working is is the firmware can not handle the LCD RS signal .....LCD RS on mega2560 is working good ,but on due not woking good ,the signal seem has random noise .... I have try 3 solutions :1) make a lcd adapter with ic 74hc07 (nxp product , totally new !) 2) check the signal without RAMPS-FD ,mainly check D16 (LCD RS ) and D17(LCD E) ,I find out that D17 working good . 3) I changed D16 to D23 ,in order to make sure that not some function of the MCU make the signal has random noise , the result is the same as D16 . Of course I also check D16 D17 D23 are not broken with arduino IDE exsample programe "blink " ,I changed io and make delay down to 5mil seconds (in order to make a square wave ) .
base on above ,I think the Repeter firmware for due has some issue on this .... Of courese ,this conclusion is not confirmed by repetier , so I need you guys helps ,Dose anyone make the lcd working good with RAMPS-fd on due ?pls let me konw .THX lots !

A 74HC07 is not a good way to make a high speed level changer as you get a slow rising edge, depending on the pull up resistor. A 74HCT08 or similar should be used to go from 3.3V to 5V logic. It will run from 5V but accept TTL logic levels which are compatible with 3.3V CMOS.

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[www.hydraraptor.blogspot.com]

I got it ,maybe is the fireware can not handle the signal voltage well , when I try to make a SD CARD work with repetier ,I found that the repetier sdfat.h can not make SPI work ,but arduino original SD.h can... of course this issue happened on arduino due ,mega2560 don't have this problem . So I have reported to repetier on github , and I have try servel SPI speed ,but all fail...I have make the LCD communation with MCU by I2C ,instead of directly....

The bobc's adaptor [www.geeetech.com] can be used or not? I can't understand.

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Motedis_kossel delta printer
Ramps1.4 for Due

A late reply, but pertinent . . .

I find that both the smart controller and graphic smart controller work with the Geetech hardware. What I also found, is that on an Arduino Due board, the U8Glib definition that was created for the graphic ST7920 lcd does *not* work . . . (I have read notes about hardware SPI not working on the Due). The good news is that dumping the Marlin-centric U8Glib definition, and using the stock one from U8Glib works fine. Details are in a thread in the development firmware section, in the thread "Marlin4due" The good newsis that this change is a one line edit!

- Tim