How To: BrewPi LCD Add-On

I have two of these running now, both with Bluetooth radios, and have found no bugs. It will work with relays and SSRs.

It will not prevent LCD scrambles - because those do not originate on the shield...

Cheers!

 

I'm in California but will ship worldwide.

 

What causes the lcd scrambles?

 

Gremlins

 

Because I2C LCDs exhibit the same issues - and those don't use a shield at all - the evidence points to noise/Vdroop/wbarber69 gremlins on the power/gnd connections to the LCD.

Could be due to inductive noise caused by the relay coils (though the SainSmart dual relay modules many of us use have snubbers in place).
Could actually be AC line sag when a compressor turns on feeding back to the power supply that feeds the LCD. That assumes that there is a single line cord that supplies power to both the controller & LCD and to the relay-switched loads - which I suspect is common to pretty much everyone's builds.

Cheers!

 

Anyone got a full parts list for the current brew pi shield v1.1?

 

I haven't put together a write up yet on the board, but you can use this link for a list of the parts.

https://www.mouser.com/ProjectManag...jectGUID=58a4b209-8794-4e83-abe7-86ceca4ae1f4

 

thanks

 

Any Reason why you used a 1N4001 over a 1N4007? I see the 1N4007 is cheaper but that could be due to it not being as demanded. I just wondering if the 1N4001 is better for this application? and the reason you used it vs others?

Also is R2, R3, R5 the same Cap? and does it Matter if the 20ohm resistor is 1/2W or 1/4 for R10?
and will the following encoder work fine?

http://www.aliexpress.com/item/IMC-...99.html?spm=2114.13010208.99999999.365.5QDOQg

 

- R2-R5 can all be 10K ohms.
- I would stick with 1/2w for R10 for the back light LED current.
- if using the PCB, it fits 1/4W resistors for all but R10. Using larger parts will be a pita.
- that encoder will work perfectly
- 1n4001 was specified only because that's what I had in my parts bin when I built the first protoshield.
In this application pretty much any diode in the 4001-4007 space will work, all we're looking for is the forward voltage drop.


Here's a copy of cadibrewer's schematic for parts references...



Cheers!

 

@day_trippr - I spec'd a 1/8w for R2 as that's how you had your protoshield set up. Why the 1/8w there instead of 1/4w?

 

Ah...I had to go back through the revision progression back to my initial drawing, which was for a breadboard with support for just the LCD alone, to see where that came from.

At that point there was just the one resistor - the pull up on the shift register - and I used an 1/8w because that's what I found first while digging in my bag o' random resistors.

As I added support for the rest of the features I forgot to change that reference...

Cheers!

 

@Bigdaddyale I'm interested in a board. Can't seem to send you a PM.

 

I'm not sure how to change the settings in the control panel. I think I have to add you to my contact list. I have two more boards left. I sent you a PM

 

I thought the story would go something like that

If I update the board in the future, okay to go all 1/4w, including R10, or should R10 stay 1/2w?

 

I'd stick with 1/2w for R10. The sink current for the DM2004A LCD backlight can range from 30mA for the white-on-blue LCD up to 180mA for the yellow-on-green LCD...

Cheers!

 

That lcd runs on 5 volts correct? I worked out from the info you provided the watts on a yellow screen would be 0.180x5 = 0.9watts and on blue it would be 0.03x5 = 0.15watts. So even on a 1/2 watt resistor on a yellow lcd it's still under rated. but on a blue you could get away with a 1/4 watt resistor.

 

Thanks to all that ordered a board. All the boards are gone.

 

Not 5 volts. You forgot the two forward-voltage drops across the two diodes.
If you go with .7v each you're down to 3.6v against a worst-case spec...

Cheers!

 

One day they'll learn to never question the tripper…

 

So what's the calculation as at 3.6v x 0.180 = 0.648watts on yellow lcd. 1/4 watt will work easy on the specs you gave on the amps for blue lcd.

 

.64 > .25

 

Could you Dm a rough price, I'd love a neater package, I'm scared to move mine in case a connection comes loose.

Cheers

 

Ok, last go around on this.

The spec for the LCD backlight current draw is at the minimum a worst-case measured figure and at the maximum is a made-up number to provide plenty of CYA space for the manufacturer.

Otoh, the wattage spec for resistors always covers the worst-case performance.

I was not about to burden the shield design with a 1W resistor just to fully cover the worst-case implementation, when the odds are the LCD backlight won't draw anywhere near the maximum specified wattage, and likewise a 1/2W resistor will not expire with a ~20% over-power scenario.

Use whatever size resistors you want...

Cheers!

 

Don't forget the approximately 2V drop for the LED itself.

 

OK that clears things up

 

Would the following module have benefits for the designed over using the current chip on the shield? and have you used this module before? and if not Do you think it might be able to solve the Scrambling issue on the LCD?

http://www.aliexpress.com/item/1595..._6&btsid=de418f06-393a-417b-983a-3a822568b3f5

 

Considering another order/run? I am still interested in a board as I'm sure others are...

 

I'm not ,but it was pretty easy to order boards from http://dirtypcbs.com/ If you need help let me know.

 

So what you have there is an I2C parallel port chip on a small pcb - I think that is often referred to as a "back-pack" of sorts. Ostensibly it could "convert" a parallel LCD (like I use) to an I2C LCD.

But you can already buy the same LCD with the I2C logic soldered right to the back of the display board, and with the correct hex file will do everything the parallel display does. Folks that post on HBT to the various BrewPi threads have already done that, successfully.

And they've noted the same screen scrambling paradigm.

So, no, I don't think that device would help at all...

Cheers!

 

I have been looking at getting an order of them in white. I found a supplier If I could get a order of 40 can do them at half the price.

 

Started this Topic on the arduino forum. Please sign up and add anymore info you have about the shield and anything you have tried. I believe the arduino forum would be the best place of any place to find a solution to the LCD Scrambling issue.

https://forum.arduino.cc/index.php?topic=404615.0

 

It's no mystery. The solution is to refresh the screen contents more often. There is a modified firmware image that does this.

 

Well, if it's not a "mystery", it's at the least an "unidentified paradigm"
But one thing is for certain, it's not an Arduino problem, and I wouldn't waste my time there.

It might be a stretch to call the refresh hack a "solution", but it's definitely a work-around...

Cheers!

 

Over at the link below they are asking for markings of the componets are on the pcb. Do you have a jpeg showing where and what componets go where on the pcb? Probaby beat to read the forum first.

https://forum.arduino.cc/index.php?topic=404615.0

 

https://644db4de3505c40a0444-327723...kcdn.com/7b36a6662056a68d5501c339f93ef713.png

 

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=ceca4ae1f4

 

Stupid question time.

This is a shield so it "plugs" into the top of the Arduino, right? Does the LCD plug into it the same way? Because it looks like the ... what is it called, header? Is "bent" parallel with the LCD in the pics I have seen.

ETA: I take that back. It looks like there's no header at all?

All I have is the board, no parts yet, so this may make more sense when I actually try to put it together.

 

I suppose if you soldered stake pins to the shield and a row of sockets on the LCD (or vice versa) you could plug them together, but it would make packaging a bit awkward...

Cheers!

 

Gotcha, that makes sense, especially the way you have yours packaged.

Speaking of which, where did you source your box if I might ask? That looks about perfect.