Altimeter sensor with Bela and Pd

CathyV

Hi, I would like to connect a barometer /altimeter (like the MPL3115A2) to Bela and use its data in a Pd patch. I have done projects with Bela and Pd (using analog sensors) but I have never done any i2c sensors. I have no experience in C++ (always happy to learn new stuff of course). I found this thread, should I try something similar? Or are there easier ways? https://forum.bela.io/d/936-pure-data-i2c
Many thanks for your help!

giuliomoro

Have you got the sensor with you? It looks like it should work just fine by using the Arduino library. I can guide you through it once you have the sensor and Bela ready to go.

CathyV

Fantastic! Thank you, Giulio! I don't have the sensor yet, but ordered it and will let you know as soon as I have it.

CathyV

I got the sensor and Bela ready now, I downloaded this arduino library: https://github.com/adafruit/Adafruit_MPL3115A2_Library. What would the next steps be? I looked for a thread on this forum that covers a similar topic but I did not find one (I assume it is pretty similar for all i2c sensors?). Many thanks for your help!

giuliomoro

ok download this repo as a zip archive and drag it on top of the IDE, it should prompt to create a new project from the zip. Then try and run it. It assumes that the sensor is connected on bus I2C1 (the one you find in Bela's pinouts).

https://github.com/giuliomoro/Adafruit_MPL3115A2_Bela

CathyV

Hi Giulio, thank you very much for the files, that is very helpful. I can drag it on top of the IDE, it prompts me to create a new project. With the first try I got some mistakes on an _main.pd patch missing, but I think that is because the Bela read it as a pd project? I switched to a C++ project. This uploads fine. I cannot get it running yet, but I think this is more a problem with my Bela connection (did not have more time to check), so I continue today and let you know as soon as I got it running. Thank you very much for your help!

giuliomoro

I don't think you should get any warnings about _main.pd if you simply create a project from this zip archive...

CathyV

Weirdly enough I do get warnings, but just the first time I upload (tried it with a second bela now). But the second time it uploads well. I got a few other warnings as well, I copy them all here. Many thanks for all your help!

Create project from zip archive Adafruit_MPL3115A2_Bela-main Adafruit_MPL3115A2_Bela-main.zip...

Error opening file _main.pd: file does not exist.Building project ...

Building Arduino.cpp...

...done

Building Adafruit_I2CDevice.cpp...

...done

Building Adafruit_MPL3115A2.cpp...

...done

Building Wire.cpp...

Makefile:510: recipe for target '/root/Bela/projects/Adafruit_MPL3115A2_Bela-main2/build/Wire.o' failed

Build finished

In file Wire.cpp: no member named 'readRaw' in 'I2c' column: 21, line: 78

In file Wire.cpp: no member named 'writeRaw' in 'I2c' column: 14, line: 82

In file Wire.cpp: no member named 'readRaw' in 'I2c' column: 20, line: 92

/root/Bela/projects/Adafruit_MPL3115A2_Bela-main2/Wire.cpp:78:21: error: no member named 'readRaw' in 'I2c'

int ret = master->readRaw(_address, (i2c_char_t*)buf, 1, !stopBit);

        ~~~~~~  ^

/root/Bela/projects/Adafruit_MPL3115A2_Bela-main2/Wire.cpp:82:14: error: no member named 'writeRaw' in 'I2c'

if (master->writeRaw(_address, (i2c_char_t *) txBuffer, usedTxBuffer, !stopBit) == usedTxBuffer) return 0;

 ~~~~~~  ^

/root/Bela/projects/Adafruit_MPL3115A2_Bela-main2/Wire.cpp:92:20: error: no member named 'readRaw' in 'I2c'

int ret = master->readRaw(address, buf, len, !stopBit) == len ? 0 : -1;

       ~~~~~~  ^

3 errors generated.

make: *** [/root/Bela/projects/Adafruit_MPL3115A2_Bela-main2/build/Wire.o] Error 1

giuliomoro

right, you need to update your board to the dev branch for it to work with this code, see "updating to an experimental release" here: https://learn.bela.io/using-bela/bela-techniques/updating-bela/#updating-to-an-experimental-release

CathyV

Hi Giulio, my apologies for my late reply. The Bela IDE is not working yet. I updated to the dev branch, but the IDE does not open at all on my chrome browser (neither with the other version). It does open in chrome on an older computer (intel processor, mac, Sequoia). The IDE opens on my newer computer, but just in firefox. There I cannot "run" the project ( I might have to update the bela image? current image the is v0.3.8b. I found how to update the image, so I will do that during the next few days, and then see if things function better. I will let you know then.

giuliomoro

I am surprised it doesn't open at all ... 0.3.8b is over 5 years old. Reflashing it seems the right way to go ...

CathyV

Great! Thank you for the quick answer. I don't have much time at the moment unfortunately, but as soon as I have some spare minutes I will reflash and try out and then let you know if everything works fine. Thank you very much for your help.