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Published byMelvyn Silvester Barton Modified over 8 years ago
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Real-time Closed Loop Controller Raffaele Cetrulo Rolando Ortega Hector Rubio
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Objective To design a control application: – Simple – Real-Time – Embedded – Self-contained – Externally Controllable – In real hardware
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Hardware Olimex LPC-E2294 Proto Board (http://www.olimex.com/dev/lpc-e2294rb.html)http://www.olimex.com/dev/lpc-e2294rb.html PWM LCD ARM7 TDMI JTAG Ethernet USB to RS232 Analog Input
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FreeRTOS Mini Real Time Kernel – Scheduler – Concept of Tasks – Inter-task Communication Essentially a simple Cyclic Executive ARM 7 architecture port available Free! http://www.freertos.org/
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OS Software Porting Assembly routine to start up the OS and configure interrupt vector. Configuration of timer interrupt for scheduler. Creation of tasks and/or ISRs for interfaces. – PWM, UART, ADC Putting it all together.
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ARM MCU Control Loop PI Control ADC PWM Heating Element UART Temp Sensor
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Linearization
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FreeRTOS Task Communication Idle Task LCD Handler Control Comms HAL UART ISR UART ISR ADC ISR ADC ISR Setpoint
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User Interaction Header Temp UART Header Setpoint Control LCD Handler
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Walls we slammed against Ethernet communications – Had JTAG programmer/debugger trouble. – Ended up with a tool chain that only allows very small programs. – Couldn’t fit it in there – Reverted to our contingency plan: UART. But, created a Hardware Abstraction Layer that would still allow transparent Ethernet use.
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Lessons Learned Some Open Source is great. Some Open Source is great if you are not on a deadline. – So it’s not always cheaper if it involves more development time.
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Questions?
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