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7 segment drivers?

Any recommendations on 7 segment drivers, got a little project on, been looking at the Allegro A6275etc in small quantities. RS/Farnell are charging a 30? per order surcharge on these....

Probably using the HP/Agilent/whataretheycallednow H151 series AlGaAs things 1"ish size

I've noticed that they have a seperate resistor to set the display current, anyone know of one with digital control, or will a DAC'd current mirror work?

And, it can't be multiplexed, it's for video work

The last time I did 7 seg's was with ULN200x stuff, in the 80's The SGS M5481 is sort of ok, but only has serial in , but not serial out no good for stringing them together:-(

BTW not maxim, of course.

apologies for a technical question on SED

Martin

Reply to
Martin Griffith
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This sounds like one of those stupid "use a PIC" answers but it actually makes sense here.

An F628A (etc) will drive the H151 directly if run fron 2.7 to 3.0 volts and PWM'd. Serial i/o is therefore no problem for stringing them together. Or just multiplex all the displays you require from one PIC.

Dirt cheap and no surcharge for small orders.

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Gibbo

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Reply to
Gibbo

Never been into Pics, always had the barf syndrome, reading the datasheets, but yep, begining to think that way as well, I was "doing a Joerg" on the cheapest sot23 npn's and have a dac controlled smps vary the volts,one per dual 7seg LED,easier than current sensing, still a bit/very messy.

The layout should be fun :-) Suppose I could always DMX them........

Martin

Reply to
Martin Griffith

Personally I'd use an Atmel ATmega8. It's got USART, SPI & I2C and enough pins to drive two digits all for £1.50 in one off quantities from Farnell. Contact me off-list if you want to go further with it.

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John B
Reply to
John B

It's just sort of preliminary suff at the mo. Been annoying the Atmel site all day, and it's been annoying in return, I'm going to hang onto my 8051 stuff as long as possible :-(

I've got an Imagecraft avr complier, 1st edition, somewhare, might try and see if I can get a new s/n for it, my brain can't cope with GCC

Linus T said: "How should I know if it works? That's what beta testers are for. I only coded it"'

Martin

Reply to
Martin Griffith

TLC5921 ? TI has other drivers with pwms.

Cheers

Reply to
Martin Riddle

i'll check in the morning,

thxs

Martin

Reply to
Martin Griffith

I looked at a PIC data sheet once, and when I saw "bank switching", I ran away screaming. ;-)

Cheers! Rich

Reply to
Rich Grise

Why the frownie? Once you get familiar with it, the 8051 is a pretty good processor. And they've got so many variations now, you could probably do the whole thing in one chip.

Have Fun! Rich

Reply to
Rich Grise

If you just want the output drivers, use an 'F59 for 3 cents an I/O in qty. 25.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Genlock it! :)

snark!

Gotta go with the other dude here, microcontroller is the way to go. Bigger investment up-front, but big payoff when you just twiddle code to get what you want.

Reply to
a7yvm109gf5d1

Ah, sort of an ISP frown, The at89Cxx can have a couple of trannies added and a user and download new/updated software into it from a serial port The at89Sxx needs the the atmel dongle lead, sort of impractical The S series is 6dB cheaper as well

I've always stuck with Atmel for some reason, maybe better datasheets

Martin

Reply to
Martin Griffith

It will be, obviously, but I dont want to risk any flicker

Martin

Reply to
Martin Griffith

. . .

If you end up using PWM of some sort be sure to make the switching frequency as far away as possible from any multiple of the frame rate. Otherwise you'll get aliassing.

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John B
Reply to
John B

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