The use of a Raspberry Pi as Embedded controller
Raspberry Pi: A genuine solution or only suitable for a Prototype?
The Raspberry Pi has rightly built up a good reputation within the ‘makers community’. It is a beautiful cheap computer which can be used to quickly create a complex, embedded application.
Does this also mean that it is suitable for all situations? The various aspects are discussed here.
Convenience
The required connections from the embedded application to the Raspberry Pi can be made via a connector.
The use of Linux also makes internet access for IoT (Internet of Things) applications easy.
Because it works with Linux, it can even be programmed in a scripting language such as Python or Javascript.
When the speed requirement is not too high, that works fine.
But in order to be suitable as an end solution put on the market in numbers, more is needed.
Reliability and costs
With a price of approx. € 50, it is not easy to beat the Raspberry Pi. That also explains its popularity. But the design of the Raspberry Pi had a focus on the lowest costs, not on longevity and reliability. A temperature range of 0 - 50 °C may be sufficient for indoor applications, but it is certainly not for an outdoor application. Furthermore, the connectors may malfunction over time.
The fact that the Raspberry Pi is a mass product also means that it cannot be produced in small numbers. If sales decline, production will be discontinued. Already many people have had to adapt their design with the Raspberry Pi to a successor model, because the previous model was no longer available.
For a demonstrator or prototype, availability, reliability and longevity are not important criteria.
However, if your product is placed on the market in numbers of 100 to 1000+, other probabilities of failure must be taken into account.
Then costs due to product problems and costs for support and service have to be taken into account.
If product problems occur, these will be scaled up with your sales numbers. Which is usually very undesirable.
Demonstration phase / prototype phase
In a step-by-step plan for product development, the Raspberry Pi can be used in the demonstration phase and in the first prototype. In the demonstration phase there is often no hard requirement with regard to reliability (temperature and moisture) and lifespan. Also, the physical size of the electronics is often not (yet) very critical. The Raspberry Pi will then speed up the development step and reduce costs.
Non-functional market requirements
When the demonstrator / prototype has approval (from customers and investors) an engineering effort is needed to meet non-functional market requirements.
Issues such as temperature range, shock resistance, life span, EMC and CE testing, but possibly also issues such as remote firmware updates and remote maintenance, to reduce maintenance and service costs.
These are all important issues for
embedded control electronics applications.
Pre-production development
Before the product can be produced, in this (2nd) stage of development, a production prototype will have to be made that meets all requirements.
This prototype can then be used for the approvals and certifications.
After all, this is the product that will come onto the market.
In many cases the
embedded control electronics of this prototype will not be equipped with a Raspberry Pi.
For this phase in the product development we also opt for our established development procedure in which responsible and wellfounded choices and testing are given great attention.
A project then consists of the steps:
- Describing the requirements (of the demonstrator)
- Overall design (of demonstrator)
- Detail design
- Qualification
- Acceptance tests
- Production
- Production test
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