A Bare Machine Sensor Application for an ARM Processor
Contents
1. 5 SS gt S ss Ss SS aS gt Te 7a ir oea Eo 5 gt S aS Li SS a SS es An ARM application for the temperature sensor device that runs on Windows CE as shown in Fig 8 is used for comparing with our bare application It consists of three source files and their respective header files TEM AppDlg TEM App and stdafx The application does not include graphics alarm and touch screen When these files are compiled in a bare system where the system files OS libraries are excluded there are 33 errors These errors are related to Windows CE system calls definitions and some constants During compilation the system calls for Windows CE and related libraries are included to form an executable that runs on an ARM processor In an OS environment an application programmer cannot directly access the underlying ARM facilities In the BMC system the hardware interfaces as shown in Fig 7 and the ARM facilities in Fig 4 and Fig 5 are directly accessed and managed by the bare ARM application programmer This is the main distinction between an OS based and a bare application V FUNCTIONAL OPERATION AND TESTING The development environment for the bare machine sensor device application is shown in Fig 9 The ADB board is connected to a Windows laptop using an RS232 UART cable No OS is loaded in the ADB2. The laptop is used to load test and debug the application The temperature sensor device is plugged into the ADB The ADB consists of a power switch and reset button in addition to the other components in Fig 1 The power switch is used to boot the application and the reset button is used to restart the application As noted earlier the C C bare application is developed under the Eclipse IDE which is run on the laptop We used the Telnet Hyper Terminal on this machine to communicate with the ADB Fig 9 also shows an ADB diagram with the bare memory map The map contains bareperipheral bin application executable and the images area The images are used to display some icons in the LCD bare graphics The application is loaded at Oxc0008000 and the images data is loaded at 0xc5000000 U Boot 1 1 6 is used to boot the ADB When the system is booted it displays a user menu We exit this menu using option e so that no other software is loaded in the ADB bare ADB In the U Boot shell the command dnw c0008000 bareperipheral bin is used to load the bin file The command dnw c5000000 imagefiles is used to load image files Once all the code and data are loaded the command go c0008000 is used to run the bare application When the application starts it first executes the start s code This is a small ARM assembly code segment 21 that functions as a bare boot program The assembly code then jumps to main which is the
3. bare sensor ARM applications and bare applications that are portable across a variety of mobile and pervasive devices with ARM processors ACKNOWLEDGMENT We sincerely thank NSF and in particular the late Dr Frank Anger who initially supported this work by funding through SGER grant CCR 0120155 Without his encouragement bare machine computing concept and explorations could not have been possible 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 REFERENCES L Edwards Embedded System Design on a Shoestring Boston Newnes 2003 L He R K Karne and A L Wijesinha Design and Performance of a Bare PC Web Server International Journal of Computer and Applications vol 15 pp 100 112 June 2008 P Appiah Kubi A L Wijesinha and R K Karne The Design and Performance of a Bare PC Webmail Server 12 IEEE International Conference on High Performance Computing and Communications AHPCN pp 521 526 2010 A Alexander A L Wijesinha and R Karne A Study of Bare PC SIP Server Performance 5 International Conference on Systems and Networks Communications ICSNC pp 392 397 2010 G Ford R Karne A L Wiesinha and P Appiah Kubi The Performance of a Bare Machine Email Server 21International Symposium on Computer Architecture and High Performance Computing SBAC PAD 2009 B
4. eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB ee eS eS define GPIO_ BASE 0x7F008000 define GPIO_PORT_BASE port port GPIO_BASE define GPIO_CON_BASE port GPIO PORT BASE port define GPIO_DAT_BASE port GPIO_PORT_BASE port 0x4 define GPIO_PUD_BASE port GPIO_PORT_BASE port 0x8 define GPIOREG address volatile unsigned address staticvoid conf_bank GPIO_BANK bank unsigned value unsigned mask GPIOREG GPIO_CON_ BASE bank GPIOREG GPIO_CON_BASE bank amp mask value amp mask unsigned value unsigned mask GPIOREG GPIO_PUD_BASE bank GPIOREG GPIO_PUD_BASE bank amp mask value amp mask staticvoid write_pin GPIO_BANKbank unsigned pin unsigned value GPIOREG GPIO_ DAT_BASE bank GPIOREG GPIO_DAT_BASE bank amp 1U lt lt pin 1U value lt lt pin staticunsignedread_pin GPIO_BANK bank unsigned pin return GPIOREG GPIO_DAT_BASE bank static void conf_pud_bank GPIO_BANK bank amp 1U lt lt pin 0 Fig 4 GPIO API B Design The design and implementation of LED API init read write switch state operations are illustrated in Fig 5 The init method uses the GPIO object to configure the state and status of the GPIO M bank Here the state can be HI or LOW the status is set to Output and the switch state API is used to change the LED state to on off Also the read API is used to get the
5. A Bare Machine Sensor Application for an ARM Processor Alexander Peter Ramesh K Karne and Alexander L Wiyesinha Department of Computer amp Information Sciences Towson MD 21252 apeter9 students towson edu rkarne awijesinha towson edu Abstract Sensor devices that monitor environmental changes in temperature sound light vibration and pressure usually run applications that require the support of a small operating system lean kernel or an embedded system This paper presents a methodology for developing sensor device applications that can be directly run on the bare hardware without any need for middleware Such bare sensor device applications only depend on the underlying processor architecture enabling them to run on a variety of devices The methodology is used for developing designing and implementing a temperature sensor application that runs on an ARM processor The same methodology can be used to build other bare machine sensor device applications for ARM processors and is easily extended to different processor architectures Keywords bare machine computing sensor devices ARM architecture application objects direct hardware API I INTRODUCTION The popular ARM processor is used in mobile phones sensor devices and other control applications These applications typically use an operating system OS lean kernel or they are part of an embedded system 1 We describe a methodology to develop bare ARM applicati
6. Rawal R Karne and A L Wijesinha Mini Web Server Clusters for HTTP Request Splitting 13 International Confrence on High Performance Computing and Comunication HPCC 2011 R K Karne K V Jaganathan T Ahmed and N Rosa DOSC Dispersed Operating System Computing 20 Annual ACM Conference on Object Oriented Programming Systems Languages and Applications OOPSLA Onward Track pp 55 61 2005 S3C6410X OK6410 RISC Microprocessor Rev 1 20 User s Manual Samsung Electronics Inc 2009 R K Karne K Venkatasamy and T Ahmed How to run C applications on a bare PC 6 ACIS International Conference on Software Engineering Artificial Intelligence Networking and Parallel Distributed Computing SNPD pp 50 55 2005 A Peter R K Karne A L Wijesinha and P Appiah Kubi The Design and Implementation of Bare PC Graphics 7 International Multi Conference on Computing in the Global Information Technology ICCGI pp 315 320 2012 R Engler and M F Kaashoek Exterminate all Operating System Abstractions 5 Workshop on Hot Topics in Operating Systems p 78 1995 The OS Kit Project School of Computing University of Utah http www cs utah edu flux oskit Last Accessed Aug 2012 Tiny OS Tiny OS Open Technology Alliance University of California Berkeley CA 2004 http www tinyos net Last Accessed Aug 2012 J Lange et al Palacios and Kitten New High Performance Ope
7. are Application 8 UART Console Touch Screen 6 RS232 3 Bare Graphics 7 OGOOGO TO a TOWSON LCD 2 oaoa Daa on fl E ED AADA EEIN Buzzer 5 gi di i as d dido Sowy UAS N t Mo oe ___ Temperature SD Card 9 y Z Sensor 1 Fig 1 ARM Development Board ADB 978 1 4673 5208 6 13 31 00 2013 IEEE II BACKGROUND AND RELATED WORK Most computer applications require OS calls in some form These OS calls enable applications to access hardware resources at run time In contrast bare machine applications eliminate the OS by using their own bare interfaces to the hardware 9 These interfaces may for example enable program load screen display mouse and keyboard access process management and network or audio card control A given application only includes the interfaces that it needs By eliminating the OS kernel and all forms of intermediary system software the application is given full control of the hardware Details of a bare graphics application for an ARM processor are given in 10 In this paper we describe a bare application for a sensor device that runs on an ARM processor Many approaches to eliminate OS abstractions or reduce OS overhead have been proposed beginning with Exokernel 11 OS Kit 12 provides the components to build an OS while Tiny OS 13 is designed for sensor applications Palacios 14 is an example of a lean kernel Translating x86 code to run on ARM processor
8. contained and do not require any other system libraries kernel or OS The application programmer controls all aspects of program development In BMC a program consists of a single monolithic executable referred to as an application object AO 7 It 1s possible to have one or more end user applications programmed as a single AO We implemented the bare sensor device application in the ARM GNU C C language under the Eclipse development environment The application program consists of code for main gpio display gfx graphics adc_touch touch screen led thermol820 thermometer as shown in Table I The source and header files for these functions along with their code sizes are shown in the table The number of lines of source code including comments is 1509 and the header file code is 355 lines This is the complete code required to execute the bare application at run time There are no additional system calls or libraries used at run time TABLE I BARE CODE SIZES Source Lines of Header Lines of File Code File Code Start s D OS vs Bare Machine Interface Characteristics In an OS based system the GPIO interfaces are more complex and involve many components The GPIO C Linux file hierarchy is shown in Fig 6 The large number of levels in the hierarchy and its interdependencies reflect the complexity in an OS environment Numerous header files which call other header files in the hierarchy are also required In the
9. device application it requires several components as shown in Fig 1 A brief functional description of this application is as follows The application is loaded from the SD Card interface Label 9 into memory using U Boot A temperature sensor Label 1 is plugged into the ADB to monitor the current room temperature with a sensing granularity of 900 microseconds As the temperature changes its value Label 8 and a graphic image Label 7 is displayed on the LCD screen Label 2 An output console is used to debug the inner working of the ADB and temperature Label 3 An LED light Label 4 provides a visual indication of temperature sensor operation A buzzer Label 5 is used to trigger an auditory alert based on a pre defined temperature threshold Also the LCD screen color is changed to red to provide a visual alert with a button icon to disable the buzzer via a touch screen interface Label 6 The ADB is used to illustrate the development of a bare temperature sensor device application without any middleware or kernel The rest of the paper is organized as follows Background and related work is presented in Section II A development methodology for building bare machine applications for ARM sensors is described in Section II The design implementation and interface details together with code snippets are provided in Section IV Functional operation and testing is discussed in Section V The conclusion is contained in Section VI B
10. figure nodes indicate the header file or an implementation file and the links indicate the connectivity between different files This tree has 24 required nodes IRQ Thread Flags Checks File System I O Control Lock Bit Operation Type Checks Procedure Trace and 29 required inter dependent links In addition it also has some optional nodes and links An OS based system has to cover all possible uses of an interface for generic application development In this case GPIO C provides an API for any type of application that runs on an ARM processor under Linux In contrast a bare machine sensor application only requires the GPIO interfaces in Fig 7 which are specific to this application There is no hierarchy 1 e the BMC model is flat and the layers of complexity in the OS environment are avoided The BMC paradigm thus allows applications to be completely autonomous self controlled self managed and self executable by removing the centralized control in an OS based approach main c gpio c display _sw c gfx c adc_touch c led c thermo1820 c leh hich aoc ok6410 bare lib epioh ok6410 bare lib uarth ok6410 bare lib timer h Fig 7 Bare machine GPIO interface structure 49 amp XQ Be EJ aw ndows CE Temperature Test _ a Ik Temperature connect Doc Fig 8 Windows CE temperature application SON S S SS z Z 5 5
11. ifies the interfaces needed for developing a bare temperature sensor device application This figure illustrates how the software API and external peripherals communicate with the internal hardware In this application the software API was designed and implemented for Touch Screen LCD Display UART RS232 Timer LED Buzzer and Thermometer Sensor Device The figure also indicates the actual interfaces designed and implemented for each class of API e g LCD display init clock cycle write _frame We designed and implemented 20 software APIs for this application Internal Hardware Samsung OK6410 ADB GPIO BANK Software API Peripherals ADC a init polling read_touch Clock VSync HSync init clock_cycle write frame LCD Display I I I I I I I I I I I I I I I I I I I I I I I init read write char l I I I I I I I init start delay stop i l I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I LCD Display Baud rate bits parity init read write switch_state VDD HI LO PWM freq ratio timer ur init read_temp Sensor Device Thermometer Fig 3 System interfaces DQ reset write read Sensor Device Thermometer l l l l l l i PWM prescaler l l l l l l l l The GPIO object is the key element of this application It pr
12. ons where the application directly communicates to hardware without any middleware or OS Previously a variety of bare PC applications have been built 2 3 4 5 6 These applications are based on the Bare Machine Computing BMC paradigm which was originally called the Dispersed Operating System Computing DOSC paradigm 7 The BMC paradigm allows an application programmer to have sole control of the application and its execution environment When computing devices or hardware system is bare it could become ownerless pervasive adaptable and re configurable to suit the needs of an application The bare hardware or system can be used by any user anywhere without concern for sharing resources A portable device such as a USB flash drive can be used to carry the bare machine application and run it on any bare machine The BMC paradigm enables computing to be polarized on applications rather than computing environments This paper describes the approach and methodology used to build a bare machine ARM application for a sensor device The methodology is illustrated by means of a temperature sensor application that runs on an ARM development board ADB 8 We use U Boot the Universal Boot Loader to load and run the bare application The U Boot is the only tool needed to bootstrap and load the application which is independent of any operating system lean kernel or embedded system In order to build a bare machine temperature sensor
13. ovides the internal implementation for the above software APIs Sample code snippets to illustrate the GPIO API implementation is given in Fig 4 The interfaces use macros as defined in the define statements It can be seen that these interfaces directly manipulate GPIO facilities We used GPIO banks A E F I J and M consisting a total of 63 8 5 16 16 12 and 6 pins The connectivity of these pins and the bank registers are obtained from the SoC User s Manual 8 Details of the sample GPIO interface read_pin in Fig 4 are as follows The GPIO BASE definition is a pointer to the starting address of the GPIO banks There are three basic GPIO registers which are crucial to the development of the GPIO API The GPIO Configuration Register is used to initialize the pin for configuring it as an input or an output The GPIO CON BASE provides the definition for this register The GPIO Data Register is used to load or store the data The GPIO DAT BASE provides the definition for this register The GPIO Pull up Register is used to provide an impedance match to the connection The GPIO PUD BASE provides the definition for this register In the bare sensor application all these GPIO resources are directly accessed and managed by the programmer and not by other middleware i e the programmer needs to control the hardware operation of these registers in the application Pw ww ewe es ese ese es eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB eB
14. propriate bare interfaces for the ARM sensor application Also an appropriate development and hardware execution environment needs to be chosen to build test and debug bare applications since there is no OS support In some cases an integrated development environment may help to speed up the bare application development process Based on the type of sensor device appropriate ARM interfaces GPIO UART USB etc must be selected to implement a given application Furthermore a generic ARM API must be developed to make the applications robust In addition an appropriate compiler and linker for the programming language must be available to create the bare application modules Sensor application testing and validation are especially challenging in a bare environment V Understand peripheral protocol and interfaces to ARM Architecture GPIO UART USB SPI IC2 and SDIO v Understand product spec datasheetfora given sensor device W Identify sensor device pin configuration that are relevant to ARM Architecture peripheral protocol V Selecta bare ARM sensor device platform for development ADB ARM Development Board W Identify ARM interfaces that are needed for this sensor device W Design ARM interfaces API forthe above interfaces 7 Design and implement sensor device application using the above API V Test and validate the sensor device application S Fig 2 Bare machine sensor development methodology Details of the bare
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16. s is the focus of 15 In 16 17 the Java virtual machine is run directly on hardware in an embedded system BulkCompiler 18 is a simple compiler layer that works with ISA primitives and software algorithms The BMC approach differs from previous code transformation translation approaches in that it is based on eliminating OS or kernel dependent code in applications This approach still has a dependency on the underlying architecture This dependency could be eliminated in the future by developing a generic hardware API for various architectures and eventually including these interfaces in the hardware However until the hardware API is standardized the BMC approach requires that the programmer write both application and systems code as an integral part of an application III METHODOLOGY A general high level methodology for building bare machine sensor device applications is shown in Fig 2 This methodology was used to construct the bare sensor ARM application discussed in this paper To build any bare sensor ARM application it is necessary to understand the various ARM architecture interfaces and protocols such as GPIO General Purpose Input and Output UART USB SPI C2 and SDIO This involves both system and application level programming as when building any bare application In particular internal details PIN configurations and other low level information obtained from the product datasheet are needed to construct the ap
17. sensor application that was built using this methodology are as follows We selected a temperature sensor device specifically the model DS18B20U 1 Wire Digital Thermometer 19 which has three leads GND DQand VDD The Samsung OK6410 ARM Development Board 8 was used as the development platform The sensor device is plugged into ARM s GPIO interface The GPIO API is needed to initialize and communicate with the GPIO controller A timer facility on the ADB is used to sample the sensor device since it requires a timer API for this application Similarly it is necessary to construct an API for the touch screen user interface disable alerts LCD display visual 20 UART RS232 console debugging LED Controller monitoring sensor device and buzzer alert While this methodology is specific to the temperature sensor ARM device it can be modified easily for other applications Developing bare machine applications poses many challenges as indicate above since the programmer defines architects and implements all the necessary hardware interfaces needed for the application There is no middleware or OS kernel of any kind to support the application during execution This is different from developing conventional OS based applications IV DESIGN IMPLEMENTATION AND INTERFACES This section describes the interfaces required its design and implementation for the bare temperature sensor device application A Interfaces Fig 3 ident
18. starting point of the C C application in the binary file The bare application program senses the temperature and displays the output on the LCD screen as shown in Fig 1 Testing was performed to verify that all functions in the application including buzzer LED display touch screen and sensor device output worked as intended The buzzer alarm activates when the temperature reaches a threshold value set in the application This alarm can be disabled by a touch screen interface as shown in Fig 1 Terminal Telnet Console RS232 UART Samsung OK6410 ADB No OS Memory Oxc0008000 start s main gpio display graphics touch led sensor device bareperihperals bin Oxc5000000 images el Power Switch Reset SvTIva Sensor Device Fig 9 Bare ARM application development environment VI CONCLUSION A novel bare machine temperature sensor application was described in this paper The application which does not use any OS kernel or embedded system has a direct API to communicate with and control the hardware A methodology to develop the sensor application for an ARM processor was also given In particular the bare machine interfaces to build sensor applications on ARM were identified and internal design implementation details of the relevant hardware API were presented Functional operation and the bare machine aspects of ARM were discussed The development methodology can be adapted to build other
19. state of the LED and the write API is used to set the state of the LED Note that the LED API uses the GPIO object interfaces such as gpio_ driver _open conf pud bank and conf bank The read pin operation takes two parameters bank and pin For example if the parameters are E and 5 respectively data is read from pin 5 in bank E and the value is returned The bit shifting shown in the code is needed to select an appropriate pin from the bank The other interfaces are similar to this void init void GpioDriver gpio gpio_driver_open disable pullup down for GPMO 1 2 3 fields 2bit wide gpio gt conf_pud_bank GPIO_M 0x00 OxFF GPMO 1 2 3 as Output fields 4bit wide gpio gt conf_bank GPIO_M 0x1111 OxFFFF set pin states to HI gt disable led s gpio gt write GPIO_M OxF OxF void switch_state LED NUM led GpioDriver gpio gpio_driver_open unsigned state gpio gt read_pin GPIO_M led gpio gt write_pin GPIO_M led state unsigned read LED NUM led GpioDriver pio gpio_driver_open return gpio gt read_pin GPIO_M led void write LED_ NUM led LED STATE state GpioDriver gpio gpio_driver_open gpio gt write_pin GPIO_M led state Fig 5 LED Code Snippets C Implementation The interfaces and sample code snippets shown in Fig 4 and Fig 5 illustrate the simplicity of programming a BMC application These interfaces are self
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