Wolframore
- Joined Jan 21, 2019
- 2,610
Sounds like it's the wrong reset... you need a reset for just the screen.
Help with LCD change on my synth
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I was afraid of that.
U1 is a DS1818 Power-on Reset component that generates a 150ms /RESET pulse.
That appears to be sufficiently long enough time to allow the VFD module to startup.
The next step is to try and reset the VFD by momentarily shorting pin-1 and pin-3 at the VFD connection.
(Another place is to short one of the JP1 pads on the back of the VFD module (the pad leading to the controller chip, not the pad leading to the connector. I will post a picture if I can find one.)
U1 is a DS1818 Power-on Reset component that generates a 150ms /RESET pulse.
That appears to be sufficiently long enough time to allow the VFD module to startup.
The next step is to try and reset the VFD by momentarily shorting pin-1 and pin-3 at the VFD connection.
(Another place is to short one of the JP1 pads on the back of the VFD module (the pad leading to the controller chip, not the pad leading to the connector. I will post a picture if I can find one.)
It's strange that sometimes when I do the shortcircuit, the display VDF turns OFF.
After that I Turn OFF/Turn On the synth, and it works again with random characters.
I mean, not always the shortcircuit restart the VDF, sometimes it stop working.
I tried also now the shortcircuit to PIN 1 and 3 and it does the same thing as if I do with the ground cable, sometimes resets the VDF and sometimes just turn it off.
After that I Turn OFF/Turn On the synth, and it works again with random characters.
I mean, not always the shortcircuit restart the VDF, sometimes it stop working.
I tried also now the shortcircuit to PIN 1 and 3 and it does the same thing as if I do with the ground cable, sometimes resets the VDF and sometimes just turn it off.
No.
Shorting pin-1 to pin-3 does not reset anything.
I will post a picture soon.
One of the problems is that the LCD standard pin numbering of 1-14 or 1-16 is for a single row of contacts.
For 2 x 7 and 2 x 8 connectors the numbering might not be the same.
In other words, pin-2 is now GND and pin-1 is Vcc, the opposite of a single row interface.
Shorting pin-1 to pin-3 does not reset anything.
I will post a picture soon.
One of the problems is that the LCD standard pin numbering of 1-14 or 1-16 is for a single row of contacts.
For 2 x 7 and 2 x 8 connectors the numbering might not be the same.
In other words, pin-2 is now GND and pin-1 is Vcc, the opposite of a single row interface.
I tried to connect the paper clip to the JP1 and pin-2, and sometimes seems that the vdf turn off. I did it in different ways, also turning ON/OFF while the clip was connected. Only twice the display got with correct characters.
Another thing I tried is Pin 1 and Pin2 while the synth is ON, touching with a small wire , make shortcircuit and the display looks OK.
And also, if I unplug the display while the synth is ON, and plug it again, don't show anything. Completely black.
Another thing I tried is Pin 1 and Pin2 while the synth is ON, touching with a small wire , make shortcircuit and the display looks OK.
And also, if I unplug the display while the synth is ON, and plug it again, don't show anything. Completely black.
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Connecting pin-1 and pin-2 is creating a short circuit across the power supply which will affect both the synth hardware and the VFD. Why this makes the VFD work I do not know.
U1 DS1818 RESET generator provides 150ms startup delay. This should be sufficient time to allow the VFD to initialize properly. I would guess that the problem has to do with the start-up sequence of the power supply and the proper initialization of the VFD.
At this point I am stumped and do not have a solution for you.
U1 DS1818 RESET generator provides 150ms startup delay. This should be sufficient time to allow the VFD to initialize properly. I would guess that the problem has to do with the start-up sequence of the power supply and the proper initialization of the VFD.
At this point I am stumped and do not have a solution for you.
I really appreciate. Thank you very much for all the help !
I had an idea, but I don't know if it works.
Buy a switch, that opens and close the signal from the GROUND (wire) to the pin-2.
I mean...when the switch is OFF, the ground signal not arrives to pin2, and when I turn it ON/OFF again the switch activates the GROUND, and the VDF will be seen correctly.
Is it possible do that?
The idea is:
1-Turn ON the synth with the switch in mode OFF (ground wire is not activated)
2-After that, turn ON the switch ( activates the pin-2)
3-Turn OFF the switch again (brings the VDF with the correct characters)
I had an idea, but I don't know if it works.
Buy a switch, that opens and close the signal from the GROUND (wire) to the pin-2.
I mean...when the switch is OFF, the ground signal not arrives to pin2, and when I turn it ON/OFF again the switch activates the GROUND, and the VDF will be seen correctly.
Is it possible do that?
The idea is:
1-Turn ON the synth with the switch in mode OFF (ground wire is not activated)
2-After that, turn ON the switch ( activates the pin-2)
3-Turn OFF the switch again (brings the VDF with the correct characters)
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Let us analyse what we know and what we have observed.
1) Shorting pin-1 and pin-2 at the VFD connector is creating a short circuit across the +5V supply.
This appears to get the VFD working.
2) The Samsung 16T202DA1J Specification sheet Operating Recommendations 7.5 make a note about slow starting power supply causing the module to not function.
3) When the VFD is initialized from power up, the controller assumes a default reset state:
Of note, the display is off. The interface is 8-bit mode.
4) The internal processors of the synth operate off +3.3V power supply. U1, DS1818 is a power-on reset generator chip that supply 150ms RESET delay to the MCF5206E ColdFire processor.
5) The synth interface to the LCD module is 4-bit mode.
6) Neither manual reset on the synth or on the VFD appears to work.
The only way the synth can correctly interface to the LCD or VFD module is to reinitialize the display controller to 4-bit mode. One would have to assume that the synth processor is reinitializing the display module on a repeated basis which would be unusual.
1) Shorting pin-1 and pin-2 at the VFD connector is creating a short circuit across the +5V supply.
This appears to get the VFD working.
2) The Samsung 16T202DA1J Specification sheet Operating Recommendations 7.5 make a note about slow starting power supply causing the module to not function.
3) When the VFD is initialized from power up, the controller assumes a default reset state:
Of note, the display is off. The interface is 8-bit mode.
4) The internal processors of the synth operate off +3.3V power supply. U1, DS1818 is a power-on reset generator chip that supply 150ms RESET delay to the MCF5206E ColdFire processor.
5) The synth interface to the LCD module is 4-bit mode.
6) Neither manual reset on the synth or on the VFD appears to work.
The only way the synth can correctly interface to the LCD or VFD module is to reinitialize the display controller to 4-bit mode. One would have to assume that the synth processor is reinitializing the display module on a repeated basis which would be unusual.
Thanks!
When you mean the display controller, I guess is from the VFD right?
And there is a way to reinitialize the display controller to 4 bit? Maybe software hacking?
Around all this that is happening, I'm wondering if it's because those VFD are old for the new hardware, or is just because the AKAI MINIAK model can't use them properly.
Also If the RESET generator provides enough delay time to allow the VFD to initialize , maybe is problem with those displays.
I wanted to buy more of those for my other synths because the good brightness , but I thought would be easier to install like a plug and play.
When you mean the display controller, I guess is from the VFD right?
And there is a way to reinitialize the display controller to 4 bit? Maybe software hacking?
Around all this that is happening, I'm wondering if it's because those VFD are old for the new hardware, or is just because the AKAI MINIAK model can't use them properly.
Also If the RESET generator provides enough delay time to allow the VFD to initialize , maybe is problem with those displays.
I wanted to buy more of those for my other synths because the good brightness , but I thought would be easier to install like a plug and play.
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As I said, everything suggests that it should work as is.
Why you are getting it working in the first place by grounding the VFD power supply does not make any sense.
A software hack is out of the question because we have no access to the ColdFire firmware.
At this point I have no solution to offer. I will be examining the VFD supply line to see where we can interrupt the supply.
Even if this turns out to be a working solution I have no idea why it would work and not the other solutions such as resetting the VFD module.
Why you are getting it working in the first place by grounding the VFD power supply does not make any sense.
A software hack is out of the question because we have no access to the ColdFire firmware.
At this point I have no solution to offer. I will be examining the VFD supply line to see where we can interrupt the supply.
Even if this turns out to be a working solution I have no idea why it would work and not the other solutions such as resetting the VFD module.
Anyway, Thank you very very much for all this help 
Really was so helpful and also I learn things that they were out of my knowledge.
What I will try to do, is probably try to set it into another synth that uses that display 16x2 and see if it works there.
Really was so helpful and also I learn things that they were out of my knowledge.
What I will try to do, is probably try to set it into another synth that uses that display 16x2 and see if it works there.
Hello,
I got some information from some users that own a VFD . They struggled too with those displays. Hope this message can help other users too in the future.
Here are the messages:
Me: Did you only plug and play, and it worked?
User: No plug and play here. They don'follow hitachi 44780 standard. At first there where only hieroglyphs. In this ucapps app I had to use another software display driver. But the most crucial step was to lower VDD of the display. Good luck!
User 2:
it takes RS"#" serial so wrote Arduino code to output TTL serial at 5v then used a TTL to RS232 converter, but sometimes easier get working on a PC with RS232 and a aerial terminal application .
User 3:
it was pretty straight forward on a Arduino, but I ended up writing the low level protocol for the rapsberry in Python, because I could not get the kernel module based device driver to work.
It depends a lot on the specs. Here is my repo if it helps
https://bitbucket.org/hmedchen/raspberry_spi-vfd/src/master/
Let me know if you need help, it's probably not to well documented.
Although I can't understand so much about Arduino and programming, but it seems all was problem with the config of the VFD right?
I got some information from some users that own a VFD . They struggled too with those displays. Hope this message can help other users too in the future.
Here are the messages:
Me: Did you only plug and play, and it worked?
User: No plug and play here. They don'follow hitachi 44780 standard. At first there where only hieroglyphs. In this ucapps app I had to use another software display driver. But the most crucial step was to lower VDD of the display. Good luck!
User 2:
it takes RS"#" serial so wrote Arduino code to output TTL serial at 5v then used a TTL to RS232 converter, but sometimes easier get working on a PC with RS232 and a aerial terminal application .
User 3:
it was pretty straight forward on a Arduino, but I ended up writing the low level protocol for the rapsberry in Python, because I could not get the kernel module based device driver to work.
It depends a lot on the specs. Here is my repo if it helps
https://bitbucket.org/hmedchen/raspberry_spi-vfd/src/master/
Let me know if you need help, it's probably not to well documented.
Although I can't understand so much about Arduino and programming, but it seems all was problem with the config of the VFD right?
Here are some possible reasons for it not working
1) Supply voltage slow startup
2) Power on Reset
3) Initialization and configuration via firmware code
I have experienced problem (3) with common LCD modules. The solution was to repeat the initialization process in firmware. You do not have the option to do this.
It would seem that you can get the VFD to work by interrupting the power supply. In my mind this is only possible if the MCU sends initialization code on a regular basis and this is very uncommon.
1) Supply voltage slow startup
2) Power on Reset
3) Initialization and configuration via firmware code
I have experienced problem (3) with common LCD modules. The solution was to repeat the initialization process in firmware. You do not have the option to do this.
It would seem that you can get the VFD to work by interrupting the power supply. In my mind this is only possible if the MCU sends initialization code on a regular basis and this is very uncommon.
