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Mathematica Wolfram Language Raspberry Pi Connected Devices

Find SenseHAT in Mathematica 11?

Bradley Keister

Posted 9 years ago

POSTED BY: Bradley Keister

6 Replies

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Teemu Ahola

Teemu Ahola, Nokia

Posted 8 years ago

I think I found the reason. Mathematica I2C support uses wrong I2C bus for accessing to SenseHAT. It is behind /dev/i2c-1 but Mathematica tries to use /dev/i2c-0. I created symbolic link from i2c-1 to i2c-0 and that tricks Mathematica. I will write new discussion to summarize this finding.

POSTED BY: Teemu Ahola

Teemu Ahola

Teemu Ahola, Nokia

Posted 8 years ago

POSTED BY: Teemu Ahola

Teemu Ahola

Teemu Ahola, Nokia

Posted 8 years ago

I think the issue may be with I2C detection: pi@raspberrypi:~ $ wolfram Wolfram Language 11.3.0 Engine for Linux ARM (32-bit) Copyright 1988-2018 Wolfram Research, Inc. In[1]:= FindDevices[] DeviceOpen::cameraDisconnected: The camera is not detected. Please ensure the camera module is connected properly. Out[1]= {DeviceObject[{FunctionDemo, 1}], DeviceObject[{GPIO, 1}], DeviceObject[{RandomSignalDemo, 1}], DeviceObject[{WriteDemo, 1}]} In[2]:= FindDevices["I2C"] Out[2]= {} In[3]:= However python works for SenseHAT: pi@raspberrypi:~ $ python Python 2.7.13 (default, Nov 24 2017, 17:33:09) [GCC 6.3.0 20170516] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> from sense_hat import SenseHat >>> >>> sense = SenseHat() >>> >>> sense.show_message("Hello world!") >>>

I think the issue may be with I2C detection:

pi@raspberrypi:~ $ wolfram
Wolfram Language 11.3.0 Engine for Linux ARM (32-bit)
Copyright 1988-2018 Wolfram Research, Inc.

In[1]:= FindDevices[]                                                                                                                      

DeviceOpen::cameraDisconnected: The camera is not detected.  Please ensure the camera module is connected properly.

Out[1]= {DeviceObject[{FunctionDemo, 1}], DeviceObject[{GPIO, 1}], DeviceObject[{RandomSignalDemo, 1}], DeviceObject[{WriteDemo, 1}]}

In[2]:= FindDevices["I2C"]                                                                                                                 

Out[2]= {}

In[3]:=

However python works for SenseHAT:

pi@raspberrypi:~ $ python
Python 2.7.13 (default, Nov 24 2017, 17:33:09) 
[GCC 6.3.0 20170516] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from sense_hat import SenseHat
>>> 
>>> sense = SenseHat()
>>> 
>>> sense.show_message("Hello world!")
>>>

POSTED BY: Teemu Ahola

Teemu Ahola

Teemu Ahola, Nokia

Posted 8 years ago

I noticed from journalctl that there was an instruction to add following line to /boot/config.txt: dtparam=i2c0=on That helped. Now Mathmatica is able to detect I2C and also SenseHAT. However there are some errors when reading sensors: pi@raspberrypi:~ $ wolfram Wolfram Language 11.3.0 Engine for Linux ARM (32-bit) Copyright 1988-2018 Wolfram Research, Inc. In[1]:= sensehat = DeviceOpen["SenseHAT"] Out[1]= DeviceObject[{SenseHAT, 1}] In[2]:= DeviceRead[sensehat, "Temperature"] DeviceWrite::unknownMRAAWriteError: An unknown error occured writing to the I2C bus. DeviceWrite::unknownMRAAWriteError: An unknown error occured writing to the I2C bus. DeviceWrite::unknownMRAAWriteError: An unknown error occured writing to the I2C bus. General::stop: Further output of DeviceWrite::unknownMRAAWriteError will be suppressed during this calculation. Out[2]= 42.4979 degrees Celsius In[3]:= And there are some errors in journalctl as well: Aug 29 18:00:39 raspberrypi libmraa[873]: libmraa version v1.6.1 initialised by user 'pi' with EUID 1000 Aug 29 18:00:39 raspberrypi libmraa[873]: libmraa initialised for platform 'Raspberry Pi Model B Rev 1' of type 5 Aug 29 18:00:39 raspberrypi libmraa[873]: i2c_init: Selected bus 0 Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: read_byte: Access error: Remote I/O error Any idea what is wrong? Here is my Raspberry version: pi@raspberrypi:~ $ cat /etc/os-release PRETTY_NAME="Raspbian GNU/Linux 9 (stretch)" NAME="Raspbian GNU/Linux" VERSION_ID="9" VERSION="9 (stretch)" ID=raspbian ID_LIKE=debian

I noticed from journalctl that there was an instruction to add following line to /boot/config.txt:

dtparam=i2c0=on

That helped. Now Mathmatica is able to detect I2C and also SenseHAT.

However there are some errors when reading sensors:

pi@raspberrypi:~ $ wolfram
Wolfram Language 11.3.0 Engine for Linux ARM (32-bit)
Copyright 1988-2018 Wolfram Research, Inc.

In[1]:= sensehat = DeviceOpen["SenseHAT"]                                                                                                  

Out[1]= DeviceObject[{SenseHAT, 1}]

In[2]:= DeviceRead[sensehat, "Temperature"]                                                                                                

DeviceWrite::unknownMRAAWriteError: An unknown error occured writing to the I2C bus.

DeviceWrite::unknownMRAAWriteError: An unknown error occured writing to the I2C bus.

DeviceWrite::unknownMRAAWriteError: An unknown error occured writing to the I2C bus.

General::stop: Further output of DeviceWrite::unknownMRAAWriteError will be suppressed during this calculation.

Out[2]= 42.4979 degrees Celsius

In[3]:=

And there are some errors in journalctl as well:

Aug 29 18:00:39 raspberrypi libmraa[873]: libmraa version v1.6.1 initialised by user 'pi' with EUID 1000
Aug 29 18:00:39 raspberrypi libmraa[873]: libmraa initialised for platform 'Raspberry Pi Model B Rev 1' of type 5
Aug 29 18:00:39 raspberrypi libmraa[873]: i2c_init: Selected bus 0
Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error
Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error
Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error
Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error
Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: write: Access error: Remote I/O error
Aug 29 18:01:00 raspberrypi libmraa[873]: i2c0: read_byte: Access error: Remote I/O error

Any idea what is wrong? Here is my Raspberry version:

pi@raspberrypi:~ $ cat /etc/os-release 
PRETTY_NAME="Raspbian GNU/Linux 9 (stretch)"
NAME="Raspbian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
ID=raspbian
ID_LIKE=debian

POSTED BY: Teemu Ahola