Cortex-M3 -based real-time data acquisition system μC/OS- Ⅱ and CAN bus
|Course||Computer Software and Theory|
|Keywords||Cortex-M3 STM32F103 Data acquisition μC/OS- Ⅱ bxCAN controller|
At present, the data acquisition system in various fields of engineering construction, scientific research, control is widely used, and many areas are demanding real-time and processing speed of the system, but the system cost control is very strict. ARM's Cortex-M3 core fits these requirements, this article is a Cortex-M3 processor to achieve real-time data acquisition system. This system uses the integrated Cortex-M3 core STM32F103VC chip external analog signal data acquisition, and then collected data filtering, and ultimately through the CAN bus communication transmission to another development board for processing. STM32F103VC chip based on the ARM Cortex-M3 core designed for embedded applications that require high performance, low cost, low power consumption designed specifically with the characteristics of a high level of integration and ease of development. Integrated in the STM32F103VC chip the basic expansion control the LAN (bxCAN) controller, plus TI's SN65HVD230 as transceivers, CAN bus communication. The data acquisition system is complicated, can not meet the application constituted by an infinite loop. In this paper, the μC/OS- Ⅱ real-time embedded operating system to manage the data acquisition task. μC/OS- Ⅱ in the real-time performance is excellent, and there is no development costs pressure. About μC/OS- Ⅱ operating system, the paper elaborated portable real-time operating system μC/OS- Ⅱ on in STM32F103VC chip each file code modifications. On the software side, respectively, described the development of CAN bus the ADC module data acquisition and real-time communication, design and expansion. ADC module STM32F103VC chip integrated on-chip analog / digital conversion devices (ADC) transfer data via DMA mode, reducing the use of CPU resources, give full play to the Cortex-M3 chips in real-time on performance. And the collected data will first filter processing, the median average filtering method used in this article. CAN bus module, integrated in the STM32F103VC chip bus communication interface (bxCAN), which supports the CAN protocol 2.0A and 2.0B interface is fully compatible with current CAN2.0B standards. In this paper, the initialization of the CAN bus baud rate settings, filter settings, and send message code design. ADC module and CAN bus modules are managed by μC/OS- Ⅱ operating system.