Raspberry PI 2 | Not Ready for real-life-embedded Apps (March 2015)

 

Raspberry PI (Raspberry Pi is a trademark of the Raspberry Pi Foundation) is not only used as a learning plattform – it is already used in productive environments, too. So a lot of embedded systems are based on that plattform already. And we also have some data collecting systems based on R-PI.

R-PI is not really real-time, but good enough for a lot of use cases.

So we have some in productive systems and research projects already in use.

Our latest tests showed us, that Model B and B+ are very reliable and stable – but R-Pi 2 Model B is not.

This is our test scenario:

* SainSmart 8-Kanäle RelaisModul Brett 5V Für Arduino PIC AVR MCU DSP Relay Module, Raspberry PI Model B+ (of course with an ULM2803A module in the middle and some cable), Raspian

* SainSmart 8-Kanäle RelaisModul Brett 5V Für Arduino PIC AVR MCU DSP Relay Module, Raspberry PI 2 Model B (of course with an ULM2803A module in the middle and some cable), Raspian

This is the python script we use for our tests (simple: initialize – on – off – cleanup) and runs endless (via bash script) – results:

* PI 1 Model B+: just stopped after 10 days non stop switching relais

* PI 2 Model B: first run: 242 switches – turned off, 5200 switches – turned off, 542 switches – turned off

That means for such applications PI 2 is not recommended by us nowadays – even if it is really amazing hardware – of course we go on working based on PI2 but going productive on PI1-B+ only.

Here our small python test routine:

import RPi.GPIO as gpio

import time

# peter ports = [6,12,13,19,16,26,20,21]

# port list

"""

#     GPIO-6  ==> relay 1

#     GPIO-12 ==> relay 2

#     GPIO-13 ==> relay 3

#     GPIO-19 ==> relay 4

#     GPIO-16 ==> relay 5

#     GPIO-26 ==> relay 6

#     GPIO-20 ==> relay 7

#     GPIO-21 ==> relay 8

"""

ports = [6,12,13,19,16,26,20,21]

#set pins to BCM mode

gpio.setmode(gpio.BCM)

#setup all pins for output

for port in ports:

gpio.setup(port, gpio.OUT)

#set all pins to high (relay close NO, open NC)

print("high")

for port in ports:

gpio.output(port, gpio.HIGH)

time.sleep(0.1)

#set alls pins to low (relay open NO, close NC)

print("low")

for port in ports:

gpio.output(port, gpio.LOW)

# free gpio pins

gpio.cleanup()