how am I going to make this awesome device?

[Dante Fernandez]

I missed the gravy train when this project was hot hot hot, back in 2011. Now I am coming in hot 5 years later. I just purchased 2 of the mini logger PCB boards. What's next?

[Dante Fernandez]

The BMP085 sensor is an outdated version. The BMP180 is the new standard. Can I drop this in place of the older sensor?

[Steve Chamberlin]

I believe the BMP180 is supposed to be a drop-in replacement, but haven’t tried it myself.

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[Dante Fernandez]

The Buzzer is obsolete and it looks like I am purchasing the last one from Digikey, any suggestions on replacements?

The 805 2.2uF ceramic capacitor is obsolete. Any suggestions?

The 1206 47uF tantalum capactor link is dead. Any suggestions?

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[Steve Chamberlin]

None of those parts have critical tolerances or anything really special about them. For the capacitors, you can use the search function to find other options with the same type, size, capacitance, and voltage rating - there should be many choices. For the buzzer, you may need to look at the datasheets of other piezo buzzers to find a replacement with the right pin spacing and overall size.

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[Dante Fernandez]

Thanks Steve. Got the boards as well. I hope you are still just a psyched as I am about all of this.

[Dante Fernandez]

I also see that previous versions of the PCB design allowed for a gyroscope or some sort of movement sensor. Any chance to get this back in and use it as a pedometer or compass?

[Dante Fernandez]

Many questions. For surface mount soldering I understand that a soldering station that blows hot air over the board is the best way to solder these components. You cover the board in flux and apply solder paste. When the hot air blows over the board, the solder melts all at once. Have you tried this out?

What would it take to get the max elevation range to get up to Himalayan altitudes?

[Steve Chamberlin]

It’s been a few years since I looked at this, or I think since anyone else has, so you’re going to be mostly on your own with construction and mods. The sensor was a tilt/shake switch, sort of like a modern equivalent of a mercury switch, intended as a basic pedometer. It didn’t work very well and was deleted. For the max elevation, you can change some scaling factors in the code to get a bigger range in exchange for lower resolution. I don’t recall the exact details now, but look at sampling.h for the code that scales and offsets the elevation, pressure, and temperature to fit within a fixed number of bits.

> On May 8, 2016, at 10:51 AM, Dante Fernandez <daf...@gmail.com> wrote:
>
> I also see that previous versions of the PCB design allowed for a gyroscope or some sort of movement sensor. Any chance to get this back in and use it as a pedometer or compass?
>

[Dante Fernandez]

In regards to the 1206 47uF tantalum cap, is there a specific voltage associated with this? The parts list does not have any detail other than 47uF and the link is a dead end. My options on digikey after applying the 47uF filter and 10%+/- tolerance filters are 2.5V, 4V, 6.3V, 10V as well as the equivalent series resistances of 2 Ohm, 1.1 Ohm, 800 mOhm. Any help is greatly appreciated. 

I read that  the "The XCLR pin is not physically present on the BMP180 so if you need to know that data is ready you will need to query the I2C bus." Will this at all affect the replacement of the BMP085?

[Steve Chamberlin]

That’s too bad about the capacitor. Nothing in the circuit runs over 3.3V, so anything rated higher than that should be OK. It’s part of the boost regulator filter, so you could check the regulator’s datasheet to see if a particular ESR is required for the filter cap.

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[Dante Fernandez]

I came across this and I thought that you might like it.

http://hackaday.com/2014/09/24/apollo-the-everything-board/

[Dante Fernandez]

Most of my parts arrived and I am in the soldering process. It looks like yours schematic makes use of the XCLR pin on the BMP085. The BMP180 does not have this pinout on the unit itself so it looks like this will not work. What are your thoughts? Looks like I can still grab the BMP085 unit on ebay from China. Weather it is a real Bosch part or not, we will find out.

[Steve Chamberlin]

Did you read the datasheets for the old and new parts? What did they say? Usually there’s some kind of migration recommendations for people coming from the old part. XCLR may not be needed if BMP180 already handles power-on-reset equivalently.

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[Dante Fernandez]

the PDF for the BMP180 mentions "The memory is volatile so that the writable content has to be re-written after each power-on." "Soft reset (register E0h): Write only register. If set to 0xB6, will perform the same sequence as power on reset."

Adafruit states "The good news is that it is completely identical to the BMP085 in terms of firmware/software - you can use our BMP085 tutorial and any example code/libraries as a drop-in replacement. The XCLR pin is not physically present on the BMP180 so if you need to know that data is ready you will need to query the I2C bus."

cant seem to find much else in the forums. l'll keep digging around.

[Steve Chamberlin]

It’s been a while, but I think the logger firmware only ever resets the BMP085 once when it’s first powered on. If the BMP180 does its own internal power-on reset, then that’s probably fine, and the absence of the XCLR pin won’t matter. Adafruit’s comment about using XCLR to “know that data is ready” doesn’t make any sense to me- sounds like a mistake.

If you are really concerned, I’d suggest getting a BMP180 on a prototyping board and doing a test to see how it behaves. In the worst case, it sounds like you’d only have to make a minor firmware change to the logger to send a soft reset command instead of toggling the XCLR pin.

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[Dante Fernandez]

Awesome, thank you

[Dante Fernandez]

Steve,

I am building up the logger classic right now. What is the AUX (VCC, GND, AIN) used for? I boxed it in Red.  Thanks, 

On Monday, May 30, 2016 at 4:21:12 PM UTC-7, Dante Fernandez wrote:

Awesome, thank you

[Steve Chamberlin]

The AUX input is not used. 

[Dante Fernandez]

Hi Steve,

I finally got a chance to get everything up and running. Totally awesome little device. I have been having fun with it watching the heater cycles kicking on and off throughout the night.

I have noticed a delicateness with my assembly. If the board gets bumped, the screen goes blank or looses its contrast. The contrast part is easy to fix but if it goes blank then you have to reprogram it to get the screen to display anything.

At this point the screen has gone blank and reprogramming it no longer display the splash screen. You can still hear the buzzer working when toggling through the menus. Its as if the programming is still there, it just doesn't display anything on the screen. I have another screen to test it with but it is the same problem with that one as well. It makes me think that this maybe a capacitor issue.

Any thoughts? Thanks. 

On Sunday, November 20, 2016 at 6:31:57 PM UTC-8, Steve Chamberlin wrote:

The AUX input is not used. 

On Nov 20, 2016, at 4:14 PM, Dante Fernandez <daf...@gmail.com> wrote:

Steve,

I am building up the logger classic right now. What is the AUX (VCC, GND, AIN) used for? I boxed it in Red.  Thanks, 

On Monday, May 30, 2016 at 4:21:12 PM UTC-7, Dante Fernandez wrote:

Awesome, thank you

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[Steve Chamberlin]

The LCD turns off automatically after a period of inactivity. Pressing any button wakes it again. But I assume that’s not what you’re talking about.

It sounds like there’s a loose connection somewhere that’s affecting communication between your microcontroller and the LCD. Check your soldering? None of the capacitors are related to LCD function.

If the LCD contrast changes randomly, you probably have a loose LCD module. Unplug the LCD module and flip it over. You'll see four metal tabs sticking through the back of the red PCB. If you look closely, you’ll notice that each metal tab has a small notch on its inner face. Use pliers to pull each tab further through the slot in the PCB, while also gently bending the tab inward towards the center of the PCB, until this notch clicks into place. This “click” holds the tab tight against the PCB, and is necessary to keep the LCD in the right position. Once you have all four tabs clicked into place, you may need to readjust the contrast setting.

Here’s a photo of what I’m talking about. The two tabs at the bottom are twisted out of correct position. The tab at upper-left is straight, but its notch/clip isn’t engaged. The tab at upper-right is correct, with the notch/clip engaged and overlapping the bare metal area of the red PCB. All four tabs need to look like that last one, in order to create even pressure on the LCD-to-PCB contacts, and get a consistent contrast on the LCD.

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[Dante Fernandez]

Steve,

That was pure genius. That is exactly what the problem was. I am wondering if I should just solder those connections or if those tabs are needed for pressure created for the metal bezel against the LCD screen. If they are just contact points, I might as well secure them. Thank you for taking the time to write up that recommendation.

[Dante Fernandez]

It is interesting how when you pull off the LCD brakeout board and put it back on, the contrast disappears. Its as if the screen's default contrast is too low for anything to appear on the screen. If you take the AVR programmer and touch it to the leads on the board, the supplied voltage from the USB then causes the LCD screen contrast to go up enough for you to see text on the screen in which you can go to the system setting and jack up the setting to a healthy 36.