BMP180 Pressure Sensor

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hgeorges
 
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BMP180 Pressure Sensor

Post by hgeorges »

I've been working on a project to render portable not just an altimeter and i have come across a wall if i may call it so.

This project is running on a Raspi. B 512MB normal mode
The BMP180 is connected exactly as follows to a PermaProto 1/2 size board :
VIN to 3v3, GND to GND, SDA to SDA and SCL to SCL (no surprises there)
The breakout board is connected with a brand new GPIO connector to the back of a 2.8" tft screen

Both i2c-tools and python-smbus are properly installed and the Github code adapted to BMP085
has been downloaded and modified using the smbus 1 (removed the blacklisting as well in modprobe.d folder configuration file)

All these were double checked..
The wall is that when i am running

Code: Select all

sudo i2c-detect -y 1
The expected output is that 0x77 shows up, yet it is not the case..
I would appreciate some insight into the matter

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adafruit_support_rick
 
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Re: BMP180 Pressure Sensor

Post by adafruit_support_rick »

You're using ribbon cables to connect all of these things? It's very easy to get pins reversed with ribbon cables. You should use a multimeter to check continuity between pins to make sure they are connected the way they should be.

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hgeorges
 
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Re: BMP180 Pressure Sensor

Post by hgeorges »

adafruit_support_rick wrote:You're using ribbon cables to connect all of these things? It's very easy to get pins reversed with ribbon cables. You should use a multimeter to check continuity between pins to make sure they are connected the way they should be.
Indeed, I am. Everything is soldered properly though (TFT screen reverse connector and breakout board) can't get them wrong
Even tested out another new ribbon cable, i'll have to get a multimeter though to check for that eventuality. Thank you for your reply

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adafruit_support_rick
 
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Re: BMP180 Pressure Sensor

Post by adafruit_support_rick »

Another thing - how long are the cables? The Pi has known problems with I2C cables longer than 12 inches or so (30cm). If your cables are longer, you may need to add pullups on SDA and SCL

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hgeorges
 
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Re: BMP180 Pressure Sensor

Post by hgeorges »

adafruit_support_rick wrote:Another thing - how long are the cables? The Pi has known problems with I2C cables longer than 12 inches or so (30cm). If your cables are longer, you may need to add pullups on SDA and SCL
Hey Rick, the ribbon cable that i am using is less than 20 cm; i wasn't aware of that point so thanks for pointing it out.
Regarding the reversed pins matter, the ribbon cable is marked with a white stripe for pin 1
and is properly connected to both 2x13 male headers on the tft screen and the breakout board..

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Re: BMP180 Pressure Sensor

Post by adafruit_support_rick »

We can try replacing the BMP180.
Please email [email protected] with a link to this thread for a replacement

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hgeorges
 
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Re: BMP180 Pressure Sensor

Post by hgeorges »

adafruit_support_rick wrote:We can try replacing the BMP180.
Please email [email protected] with a link to this thread for a replacement
Thanks Rick, consider it done.

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hgeorges
 
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Re: BMP180 Pressure Sensor

Post by hgeorges »

To show the problem.
IMG_0542.JPG
IMG_0542.JPG (351.38 KiB) Viewed 453 times

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adafruit_support_rick
 
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Re: BMP180 Pressure Sensor

Post by adafruit_support_rick »

Can you post a better picture of the solders on the PiTFT? The ones on the cable header don't looks very good at all.

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hgeorges
 
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Re: BMP180 Pressure Sensor

Post by hgeorges »

adafruit_support_rick wrote:Can you post a better picture of the solders on the PiTFT? The ones on the cable header don't looks very good at all.
Here is a close up shot
IMG_0544.JPG
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adafruit_support_rick
 
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Re: BMP180 Pressure Sensor

Post by adafruit_support_rick »

Many of your solders haven't flowed over the pad. I've circled the obvious ones in the picture below.
Almost all of your solders look like "cold joints". The solder is rough and lumpy.

In a good solder joint, the solder will flow smoothly and completely over the pad, and up the pin. It will be shiny and have a concave section, like this:
Image

You want to reheat all of your solder joints. Make sure to heat both the pad and the pin. Add more solder to the ones that are solder-starved.

Please review our tutorial on soldering here:
https://learn.adafruit.com/adafruit-gui ... ring/tools
pitft_solder.png
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hgeorges
 
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Re: BMP180 Pressure Sensor

Post by hgeorges »

Fixed it thanks !

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