LPD8806 with a Lightblue Bean (ATmega328p)

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dav
 
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LPD8806 with a Lightblue Bean (ATmega328p)

Post by dav »

Should these work together? I'm getting the "few random lights" problem.

The ATmega328p on the Lightblue Bean (a BTLE/Arduino/Sensors combo) has "1024B EEPROM, 2KB SRAM". Is that enough memory for a 32 LED strip?

Or maybe it doesn't have enough clock speed to drive the PWM properly (getting beyond my knowledge here)?

I've got 5v 2amp power. Everything is connected correctly as far as I can tell.

Refs
http://punchthrough.com/bean/arduino-users-guide/
http://www.atmel.com/devices/atmega328p.aspx

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adafruit_support_rick
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by adafruit_support_rick »

The ATMega328P is plenty for 32 LEDs.

How is this all wired up? Can you post a picture?

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dav
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by dav »

So after I posted the question here, I found an old Arduino Diecimila and hooked it up the same way to that and it worked perfectly. Here are some photos of the setup back on the bean. I'm using digital pin 5 for the clock and 2 for data.

Code: Select all

int nLEDs = 32 * 1;
int dataPin  = 2;
int clockPin = 5;
LPD8806 strip = LPD8806(nLEDs, dataPin, clockPin);

void loop() {
   beanblink();
   colorChase(strip.Color(127, 127, 127), 50); // White
}
Image

There's another GND on the other side of the board. I've tried that one as well.

Image

Here is the pin information from the Lightblue Bean Arduino Guide

Image

I'm starting to think I may have a defective arduino data pins on the bean. I have a couple more at my office. I may go get them today and try again.

I've ordered an 8-channel digital channel analyzer gadget from Adafruit which is supposed to arrive tomorrow. I think that could be used to determine if proper signaling is coming out on the clock/data pins right? Is there a way to verify that with just a multimeter?

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Franklin97355
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by Franklin97355 »

You really need to solder your connections to make stable communications paths.

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dav
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by dav »

Well I want to make sure it works before I start soldering. The same temporary technique works fine on the Diecimila. Is it possible that the bean physical characteristics requires a a more stable/stronger connection to work at all?

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dav
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by dav »

On the Bean forum I just found out that their digital pin output voltage is 3v, maybe the LPD8806 needs 5v on the clock and data lines?

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adafruit_support_rick
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by adafruit_support_rick »

The Diecimila has spring-loaded contacts in the pin headers. The Bean is just plated holes. Franklin97355 is right - it won't work unless you solder it.

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dav
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by dav »

So 3v is in fact enough logic signal to drive it?

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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by adafruit_support_rick »

dav wrote:So 3v is in fact enough logic signal to drive it?
yes

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dav
 
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Re: LPD8806 with a Lightblue Bean (ATmega328p)

Post by dav »

Turned out it wasn't the connection, it was that the battery voltage had dropped too low on the bean. Running the arduino code was quickly killing the coin battery on the bean so I switched to two AA cells for beefier 3v into the bean and all is well.

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