Bela displays using I2C pins?

ok, I'm confused... what is going on with the distribution sources for bela (0.2.0a)

I can see that an armhf packages is available on debian wheezy, and it appears this is in the source list
deb http://ftp.us.debian.org/debian/ wheezy main contrib non-free

but its just saying no candidate for things like libzlib1g-dev and libjpeg8-dev...
and ive done both apt-get update and upgrade

unfortunately i cannot find the source for libjpeg8 so i cant build it , like i did for zlib....

really frustrating, that i cant just pick up the sources, or the packages...

for me apt-get install worked fine with zlib1g-dev, while libjpeg8-dev seems to have been replaced by libjpeg62-turbo-dev, which installs just fine, at which point
pip install Pillow works fine.
Check the following:

a) before any apt-get operation, is the date on the board correct? (it should get it from the network, but just double check. Opening the IDE page in the browser after a reboot will set the current date (which will be reset at the next boot)
b) run apt-get update before trying to apt-get install
c) I am using the image v0.2.0b, December 2016, I think you are not (as denoted by the missing /var/cache/apt/archives/partial, see here). I think apt-get update should fix your issue, otherwise try upgrading to this release: https://github.com/BelaPlatform/bela-image/releases/tag/v0.2.0b_stable

Or perhaps the apt-get upgrade bit screwed up things? We had to add jessie repositories to this image (despite it being Wheezy) to get some of the newest stuff, which is why - I imagine - some things may get screwed if you upgrade.
Again, the steps above work fine on 0.2.0b

yeah, id already tried the update without the upgrade... and wasn't working so i think its a 0.2.0a issue.
I'll install 0.2.0b later to try to resolve

anyway, manually installed the deb, and now Pillow is installed.. thank you for that
now I'm getting a 121 io error on i2c_bus 1, using the breakout molex header.

all seems to be wired correctly, 3.3v to VDD, GND to GND , SCA to SCA , SCL to SCK(?!) , P9_12 to RST

thoughts, is there a simple way to test the I2C?

Try i2cdetect -y -r 1

it looks like there may be something wrong with the connection: the activity you see is probably due to the master (the BBB) trying to communicate to the slave.

Can you try

grep "97c\|978\|980\|984" $PINS

just to double check that the pinmuxer settings are ok?
You should get

pin 94 (44e10978) 00000073 pinctrl-single
pin 95 (44e1097c) 00000073 pinctrl-single
pin 96 (44e10980) 00000073 pinctrl-single
pin 97 (44e10984) 00000073 pinctrl-single

Also, while Bela is not running, you could try to connect your I2C device to the i2c2 bus. There you should see something like this when nothing is connected:

# i2cdetect -r -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- 18 -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Which is the audio codec for Bela. If you plug in your device, then the above should change to show up your device.

Running another I2C device on the same bus as the one used for the Bela audio codec is fine as long as you make sure that you do not communicate with that device when a Bela program starts ( the codec is configured every time the Bela program is started).

giuliomoro it appears to also have the same issue on a rPI3...

can i use SPI on bela? perhaps that will work

another note: there are two SPI busses broken out the P9 header, but only SPI0 is usable when the McASP is activated, as the latter takes over the pins where SPI1 would be available. SPI0 is in use by the Bela analogs.

Hi all,

Apologies in advance for being the newest of noobs - I have (hopefully) a very basic question! This appears to be the relevant thread, but if not then I will delete and re-post elsewhere.

I have an I2C accelerometer, which I want to use to control a libpd patch. I've connected the accelerometer to the corresponding I2C pins on the Bela cape (GND, 3.3V, SCL, SDA), and I'm able to drag-and-drop my Pd patch into the IDE, but what should I add to my Pd patch so that it recieves the accelerometer input?

Many thanks

papa_sangre Correction: It's actually an Accelerometer + Gyroscope: GY-521 MPU-6050 Module 3 Axis Gyroscope + Accelerometer.

I2C sensors are not supported by default on Bela within Pd. The reason for this is that each of them have a very specific interface and data structure that is very hard to generalize. So if you want to bring I2C sensors in, you will have to write some C++ code to read and parse the data coming through the I2C bus , then you can pass the readings into pure data.
There is an abstract class I2c in the core code in Bela/include/I2c.h and example implementations of that class for mpr121 and touchkeys sensors are in Bela/core/I2c_TouchKey.cpp, Bela/include/I2c_Codec.cpp and Bela/examples/06-Sensors/capacitive-touch/I2C_MPR121.cpp.

All this code would go in a render.cpp file within your Pd project folder. See for instance the 08-PureData/customRender example.

giuliomoro Ok, I'm going to give that a shot - thanks Giulio!

hey giuliomoro ... I'm trying to get some I2C communication going on the Bela. But I'm not using the Molex connector (rather I'd like to connect directly to the headers of the BBB via a custom capelet). I'm a bit confused though.. in the document you linked I see that the Bela is using pins P9.26 & P9.24 ... but in the BBB documentation these pins the TX and RX pins for UART1. Am I missing something painfully obvious? I want to make sure I'm tapping into the right pins :-)

I2C1 header (broken out to the molex connector on the Bela cape but unused on the board)

"P9.26", 0x180 0x73 / i2c1_sda, MODE3 | INPUT_PULLUP | SLEWCTRL_SLOW /
"P9.24", 0x184 0x73 / i2c1_scl, MODE3 | INPUT_PULLUP | SLEWCTRL_SLOW /

that is because each pin can have multiple function, and the name of a pin is "randomly" chosen as one of the names of the functions it can have. So yes, those two pins are CALLED "UART1 Rx/Tx" however, they can perform different functions, including I2C. And the function that is active by default on Bela is ... I2C!

Ah! I didn't realize that. Thanks :-)
I guess these pin modes are all set and configured at a low level in the Bela OS.