Smallest (cheapest) micro and LCD

[WizzBall]

Hello everyone,

I have a fairly simple question that will draw on your experiences with micros and parts so far.

What is the smallest and/or cheapest micro (that you know of) capable of:

Must haves:
- SPI communication (sw)
- Capable of driving a very small LCD
- SOIC package

Nice to have:
- USB capabilities

[PIC is preferred but I have no issues with other brands.]

The other part is an LCD to pair with this micro - does anyone know where can I get a small LCD (1 line) - the kind that only displays 2-3 digits (like the ones in cheap digital gadgets or thermometers)?


Thank you very much!

 

[blueroomelectronics]

The 16F916 can directly drive a small 2.5 digit 0.5" LCD.
**broken link removed**

Digikey.ca sells em both.

 

[WizzBall]

Thank you very much Bill, I am looking into both right now!

 

[WizzBall]

Bill, I just looked into it and I have one additional question. The LCD module works at 5V while the rest of my circuit works at 3.3V - I am wondering if this could be a potential problem. From your experience would such a setup work with a 5V LCD?

Thank you!

 

[blueroomelectronics]

The LCD shown works at 3V to 5V. Creatron Inc on College in Toronto has a 3V LCD seven segment glass. It's from TopWayDisplay in China.

Search for Cricket here in these forums for more info and a code example.

 

[WizzBall]

Many thanks Bill, as always - very helpful!

 

[DirtyLude]

Any chip that can use its ports as source or sink can drive a static LCD as long it has the pin count. I'm just mentioning this in case there' a cheaper alternative.

 

[WizzBall]

Thank you Mark, I'll keep that in mind!

 

[blueroomelectronics]

Remember LCD glass does not like DC it can damage the LCD.

 

[DirtyLude]

Ya, you have to alternate source and sink to give you the positive/negative swings. Here's a nice article on the basics.

**broken link removed**

 

[WizzBall]

Thank you for both your inputs into this, maybe I'll try it once I get the LCD!

 

[be80be]

Thanks for the post Mark I been look for data on how to use static LCD thats a good link.

 

[DirtyLude]

If you want a really cheap micro and an external LCD driver solution, you can get an NXP external controller from Digikey for $1.71. You can also look at this datasheet if you want to see the waveforms you need to generate if you have shared pins and multiple common pins.

Part #: PCF8576DT

https://www.electro-tech-online.com/custompdfs/2009/07/PCF8576D_8.pdf

I have not used this myself. I did experiment with direct drive and it works well, but since I can get the 7110 glcd's for $1 each and they only take a couple mA's when running, I never ran with it.

 

[WizzBall]

Mark,

I think I have one of those 7110 glcd's... any idea where I can get the connector for it? It seems to be non standard. And where do they sell for $1? I got it from Dipmicro for about $3 .

Thank you!

 

[DirtyLude]

Mark,

I think I have one of those 7110 glcd's... any idea where I can get the connector for it? It seems to be non standard. And where do they sell for $1? I got it from Dipmicro for about $3 .

Thank you!

This guy sells them for $1 each. I noticed he only has a lot of 24 going right now.
Shop eBay Canada Store - Experimenter's Discount Warehouse:: PLCC, Red

I made up a footprint in Eagle and use a bit of flat bar and 4-40 bolts to hold it all together. You can see the pictures in the other thread. The Eagle library is in there as well.

 

[nickelflippr]

Nice to have:
- USB capabilities

[PIC is preferred but I have no issues with other brands.]

As far as I know the 18f14k50 (or 18f13k50) is going to be the smallest pincount USB chip from Microchip. Will fit all requirements except driving the bare glass LCD. It's a little peculiar though, as the D+, D- pins share the PGD and PGC pins. The 18f version is the 5V version with a 3.3V internal regulator, or use the 18LF version for straight 3.3V supply.