in trouble with LCD (JHD162A)

[mvs sarma]

I understand Eric,
Wish you all A Merry Christmas

 

[ericgibbs]

I understand Eric,
Wish you all A Merry Christmas

Many thanks... Wishing you a Prosperous New Year!....

 

[mvs sarma]

The value depends on the LEDs' current, that is usually specified in the datasheet of the LCD module. If you're assembling this circuit on a breadboard, just leave pins 15 and 16 of the LCD floating (no backlight) and see what happens.

I used JHD162A display earlier. I used a 10 ohm resistor and worked fine. this might help you in settling the resistor value. the pot used for contrast could be replaced with 10K and 1K2 (lower value towards Vss). this will not leave things to chance for the O P

 

[smileguitar]

I'm upset now, the LCD still not displaying any character. I tried to connecth the backlight with resistor, nothing display at all. Then I changed output port, cannot work as well. I change the breadboard I used also not function. All the possiblity that may cause the LCD not working have been try.... What should I do now? change a new LCD?

Thanks!!

 

[mvs sarma]

don't be upset for every failure. this is where you really learn, hardware or software- if everything works as you wire- there is no learning-- FINE--

check with ref to pin1 of LCD the DC voltage on pin3of the LCD.
it should be around 0.8 to 1.4 V Dc approximately.
if it is more , it will show all dark rectangles( each character is made up of 5*7 dots which forms a rectangle) under situations all the 35 dots will turn dark. like that all 16*2 characters turn dark rectangles.it should be adjusted around 1V+/- 0.25

then the display will come up.

then check up the connections for correctness and for dryjoints.
try to connect a 0.1uF capacitor across pins 1&2 of the LCD .
i have used it across various softwares and it works.

however please check whether any of the COBs(Chip On Board) on the back of display is WARM or HOT. this happens if you have pulled out the display while it is working.(NEVER DO IT IN FUTURE) If so, I feel it should not happen, the display has gone and you may have to replace. please give a feed back.

 

[smileguitar]

don't be upset for every failure. this is where you really learn, hardware or software- if everything works as you wire- there is no learning-- FINE--

check with ref to pin1 of LCD the DC voltage on pin3of the LCD.
it should be around 0.8 to 1.4 V Dc approximately.
if it is more , it will show all dark rectangles( each character is made up of 5*7 dots which forms a rectangle) under situations all the 35 dots will turn dark. like that all 16*2 characters turn dark rectangles.it should be adjusted around 1V+/- 0.25

then the display will come up.

then check up the connections for correctness and for dryjoints.
try to connect a 0.1uF capacitor across pins 1&2 of the LCD .
i have used it across various softwares and it works.

however please check whether any of the COBs(Chip On Board) on the back of display is WARM or HOT. this happens if you have pulled out the display while it is working.(NEVER DO IT IN FUTURE) If so, I feel it should not happen, the display has gone and you may have to replace. please give a feed back.

Really thanks for your advise. I'll give you a feed back soon. Thanks...

 

[smileguitar]

don't be upset for every failure. this is where you really learn, hardware or software- if everything works as you wire- there is no learning-- FINE--

check with ref to pin1 of LCD the DC voltage on pin3of the LCD.
it should be around 0.8 to 1.4 V Dc approximately.
if it is more , it will show all dark rectangles( each character is made up of 5*7 dots which forms a rectangle) under situations all the 35 dots will turn dark. like that all 16*2 characters turn dark rectangles.it should be adjusted around 1V+/- 0.25

then the display will come up.

then check up the connections for correctness and for dryjoints.
try to connect a 0.1uF capacitor across pins 1&2 of the LCD .
i have used it across various softwares and it works.

however please check whether any of the COBs(Chip On Board) on the back of display is WARM or HOT. this happens if you have pulled out the display while it is working.(NEVER DO IT IN FUTURE) If so, I feel it should not happen, the display has gone and you may have to replace. please give a feed back.

Sorry for late reply since recently is quite busy for other assignment.

I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?

Thanks!

 

[ericgibbs]

hi,

>>I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?

If you are trying to run the program I posted 'lcd2line1', that works OK in the PIC.
Its most likely you have a problem in your hardware.

I have found that different LCD's do have a different pixel block contrast level.

As I suggested, write a simple LED ON/OFF program and prove the hardware for the remainder of the project.. once you are sure the project works without the alpha-numeric LCD, then you can get an idea if the LCD is faulty or not.

 

[ericgibbs]

hi,

>>I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?

If you are trying to run the program I posted 'lcd2line1' that works OK in the PIC. It most likely you have a problem in your hardware.

I have found that different LCD's do have a different pixel block contrast level.

As I suugested, write a simple LED ON/OFF program and prove the hardware for the remainder of the project.. once you are sure the project works without the alpha-numeric LCD, then you get a idea where the problem lies.

 

[smileguitar]

hi,

>>I've tested the LCD today. As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

Beside, you had mentioned that the LCD will show all dark rectangles if the voltage is more than 0.8 to 1.4V. But my LCD is just turn on the dark rectangles partially, and appear a few second. What does it mean for my circuit? Is the programme problem or the hardware not stable?

If you are trying to run the program I posted 'lcd2line1', that works OK in the PIC.
Its most likely you have a problem in your hardware.

I have found that different LCD's do have a different pixel block contrast level.

As I suggested, write a simple LED ON/OFF program and prove the hardware for the remainder of the project.. once you are sure the project works without the alpha-numeric LCD, then you can get an idea if the LCD is faulty or not.

Sorry, I have forgotten to mention that I didn't use your programme today because it's quite confusing. Today I had tested the hardware with a simple LED ON/OFF programme. LED works, but LCD not. Also, I used LED to test my LCD programme that I've slow down the delay time, the result is just like what I had set. But LCD still doesn't work......

 

[ericgibbs]

hi,
For the LCD test, you dont have to understand my program, just assemble it and load the hex file into a PIC and run it.

I am beginning to suspect your LCD is faulty.

 

[Pommie]

As your suggestion, I've connected a 0.1uF capacitor accross pins 1&2 of the LCD. The circuit have some improvement that the partial dark rectangles appear longer time than before. Erm...I'm not sure that I've use 2 capacitors to accross pins 1&2, which one capacitor connect to pin1 to ground, and another capacitor connect to pin2 to Vcc. Am I correct to connect by this way?

Am I right in thinking you have no connection from pin 1 to ground but instead have a capacitor?

You should have,
Pin 1 to Gnd.
Pin 2 to Vcc.
A capacitor from pin 1 to pin 2.

Mike.

 

[smileguitar]

Am I right in thinking you have no connection from pin 1 to ground but instead have a capacitor?

You should have,
Pin 1 to Gnd.
Pin 2 to Vcc.
A capacitor from pin 1 to pin 2.

Mike.

I see... I think I should connect by this way, why I never think of it. Oh my god, I'm totally lost....

Thanks for your suggestion!

 

[smileguitar]

hi,
For the LCD test, you dont have to understand my program, just assemble it and load the hex file into a PIC and run it.

I am beginning to suspect your LCD is faulty.

You mean my LCD is malfunction? But the light can be on, and some dark rectangles appear then faded down......

 

[mvs sarma]

You mean my LCD is malfunction? But the light can be on, and some dark rectangles appear then faded down......

Aa I have indicated last time, generally the failure is also indicated by additional warming-up of one of the COBs behind the JHD162A.

This happens ( at leat happened to me) when a display is inadvertently plugged out when the device is working-- plug and play culture.

 

[smileguitar]

Aa I have indicated last time, generally the failure is also indicated by additional warming-up of one of the COBs behind the JHD162A.

This happens ( at leat happened to me) when a display is inadvertently plugged out when the device is working-- plug and play culture.

COBs behind the JHD162A is slightly warm mean the LCD is burnt? Even it still can on the LCD light?

 

[ericgibbs]

You mean my LCD is malfunction? But the light can be on, and some dark rectangles appear then faded down......

This is what we are trying to find out!

Whats the problem in loading my hex file that works when loaded into a PIC, for driving a HD44870 LCD controller????

At least try it.!

 

[smileguitar]

Hi, can I know how I test the LCD is faulty or not? Tomorrow I'll buy a new LCD to test it, but before change a new LCD I need to know how to test LCD is either in good condition or not because I need to write a report and prove that LCD is faulty.

Thanks in advance!!!

 

[ericgibbs]

Hi, can I know how I test the LCD is faulty or not? Tomorrow I'll buy a new LCD to test it, but before change a new LCD I need to know how to test LCD is either in good condition or not because I need to write a report and prove that LCD is faulty.

Thanks in advance!!!

Have you tried a known working LCD driver program???

 

[smileguitar]

Have you tried a known working LCD driver program???

Sorry, what do you mean a known working LCD driver programme? I think I never tried it before. Really sorry, this is the first time I touch LCD and not really know about the well known LCD driver programme. erm... How it is try...

Thanks!!