The request
The request was to completely redesign the electronics and the firmware of an already existing instrument, the SEAC preparator, Brio.
The preparator in question is a medical machine containing a large number of drives and motors (DC and stepper) of varying outputs, heaters, solenoid valves, temperature acquisitions, pressures, positions, etc.
The existing electronics used components that are starting to become obsolete. Even the firmware, although very polished, having been written in assembly language was difficult to maintain after many years.
Other objectives were the reduction of the space occupied by the electronics, its power dissipation, and its cost.
Challenges faced
- Difficulty calibrating configuration parameters of the instrument (stepper motors, PID regulators)
- High dissipation of the power supply mode
- High number of devices to be monitored
Solutions implemented
- Used a configuration interface with command line and save loading parameters from EEPROM
- Used a switched-mode power supply
- Workload distribution on 2 CPUs in master/slave configuration
Requirements
- Redesign a laboratory instrument to update the electronics and reduce dissipation and costs
- Implement firmware with real-time guarantees
- Produce some pieces
Develer’s contribution
- Electrical diagrams, master PCB
- Testing, prototype construction
- Real-time embedded C code
- Documentation for production and testing
Results
- Performance exceeding expectations
- Extremely configurable and flexible firmware
- Low production costs
Advantages of our solution
- Innovation: new feedback systems on DC motor control have been introduced to allow a more accurate speed control.
- Flexibility: with a solely unified firmware, it was possible to manage the two processors mounted on the board, which were responsible for executing commands and even simultaneous operations on devices coordinated with each other.
- Configurability and tuning: machine tuning is quick and easy thanks to the use of a dynamic configuration system via firmware.
- Real time: time constraints were respected thanks to a careful architectural analysis and to the firmware solutions introduced by BeRTOS, our real-time operating system.
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Advantages of our approach
The transparency of the project development and the ability for the client to monitor the progress of the project in real time has allowed a process of “continuous integration”, during which every modification could be seen and tested by the client in real time on their testing device in their location.
Advantages of open source
The firmware of the instrument is based on BeRTOS, our real-time open-source operating system, which has saved us time having a considerable number of ready-made device drivers already available (stepper motors, PT100 temperature sensors, PID controllers, etc.).
Staff
“It was a great project where I was able to follow the whole development cycle, from the circuit diagram to the firmware… very exciting!”