Best way to drive a VFD from a PIC Micro? Also Happy New Year to All

[bigal_scorpio]

Hi to all, here's hoping the new year is going to be a good one.

Can anyone suggest a way of driving a VFD display from a PIC?

The VFD is a custom one from a broken DVD player and still works fine.

The problem is that besides the 3v filament supply it needs about 12 to 14v for the grids.

Other than using ULN2803 or 4 darlington driver arrays is there another way to switch the voltage to the grid that lights the segments? I would really like to use this display for a project especially since I spent hours finding the pin configurations pin by pin!

Thanks........Al

 

[vne147]

Hi to all, here's hoping the new year is going to be a good one.

Can anyone suggest a way of driving a VFD display from a PIC?

The VFD is a custom one from a broken DVD player and still works fine.

The problem is that besides the 3v filament supply it needs about 12 to 14v for the grids.

Other than using ULN2803 or 4 darlington driver arrays is there another way to switch the voltage to the grid that lights the segments? I would really like to use this display for a project especially since I spent hours finding the pin configurations pin by pin!

Thanks........Al

Do they not make a driver IC that you can use to interface the PIC with the VFD?

 

[bigal_scorpio]

Do they not make a driver IC that you can use to interface the PIC with the VFD?

Hi mate, yes they make a driver IC but they are only for standard segments 8, 14 and 16 but not for custom displays and they are pretty expensive compared to a ULN2803,and they all seem to be tiny surface mount devices.
I'm afraid that 20+ connections on something 3mm by 3mm is well beyond my soldering skills! hehehe so I'm looking for other options

 

[nigelwright7557]

I would be tempted to buy in a vfd with a driver built in to the module.
Its a big job making your own driver.

 

[vne147]

What is the segment current? Do you have to source the segment current or sink it?

 

[HarveyH42]

I have quite a few of these:



But I couldn't find a data sheet. Please keep us up to date on what you find. I'd like to use some of these things, 10 character x two lines isn't bad for a lot of things.

 

[bigal_scorpio]

I have quite a few of these:



But I couldn't find a data sheet. Please keep us up to date on what you find. I'd like to use some of these things, 10 character x two lines isn't bad for a lot of things.

Hi Harvey, your picture is not showing for me, can you repost it?

Al

 

[bigal_scorpio]

What is the segment current? Do you have to source the segment current or sink it?

Hi Mate,

From the info I could find and the tests I've done it seems the segment current and the grid current are about 10mA.

To use the display 3v dc is supplied across the filament and the neg filament connected to the neg of the 12 to 14v supply, then pos12 to 14v is applied to BOTH grid and segment in a similar fashion to a multiplexed LED display except that the digits are controlled in pairs so there can be as many as 20+ segments!

I just realised that I wouldn't be able to use the UCN280x ICs as I hadn't thought of the fact they are designed to sink instead of source! DOH!

An afterthought! does anyone know if I could use the display the other way round? I.E. commoning the pos filament and then using neg to the grid and segments?
I have IIRC read somewhere of AC being used on some VFDs.

Any help appreciated..........Al

 

[vne147]

This PIC can operate on supply voltages as high as 15V and can source up to 10 mA on a single I/O pin:

https://www.electro-tech-online.com/custompdfs/2010/01/40197b.pdf

 

[HarveyH42]

Still playing with attachments...
Click to enlarge

 

[bigal_scorpio]

This PIC can operate on supply voltages as high as 15V and can source up to 10 mA on a single I/O pin:

https://www.electro-tech-online.com/custompdfs/2010/01/40197b-1.pdf

Hi mate,

The PIC looks like it might work but not enough pins sadly, and I can't find any HV PICs with enough pins at all.

Al

 

[vne147]

I couldn't find any higher pin count HV PICs when I briefly looked either. I was thinking you could just multiplex it like crazy or maybe use a few of them in a master slave relationship. It's begining to look like there's no easy solution.

 

[bigal_scorpio]

I couldn't find any higher pin count HV PICs when I briefly looked either. I was thinking you could just multiplex it like crazy or maybe use a few of them in a master slave relationship. It's begining to look like there's no easy solution.

Hi mate,

Yep, I'm coming to the same conclusion, might have to resort to using a few dozen PNPs! Its going to be one messy circuit! hehehe

Al