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  • Figuring out the Nyquist performance limitation of an ADC on an example PIC microcontroller

    - by AKE
    I'm spec-ing the suitability of a dsPIC microcontroller for an analog-to-digital application. This would be preferable to using dedicated A/D chips and a separate dedicated DSP chip. To do that, I've had to run through some computations, pulling the relevant parameters from the datasheets. I'm not sure I've got it right -- would appreciate a check! (EDITED NOTE: The PIC10F220 in the example below was selected ONLY to walk through a simple example to check that I'm interpreting Tacq, Fosc, TAD, and divisor correctly in working through this sort of Nyquist analysis. The actual chips I'm considering for the design are the dsPIC33FJ128MC804 (with 16b A/D) or dsPIC30F3014 (with 12b A/D).) A simple example: PIC10F220 is the simplest possible PIC with an ADC Runs at clock speed of 8MHz. Has an instruction cycle of 0.5us (4 clock steps per instruction) So: Taking Tacq = 6.06 us (acquisition time for ADC, assume chip temp. = 50*C) [datasheet p34] Taking Fosc = 8MHz (? clock speed) Taking divisor = 4 (4 clock steps per CPU instruction) This gives TAD = 0.5us (TAD = 1/(Fosc/divisor) ) Conversion time is 13*TAD [datasheet p31] This gives conversion time 6.5us ADC duration is then 12.56 us [? Tacq + 13*TAD] Assuming at least 2 instructions for load/store: This is another 1 us [0.5 us per instruction] Which would give max sampling rate of 73.7 ksps (1/13.56) Supposing 8 more instructions for real-time processing: This is another 4 us Thus, total ADC/handling time = 17.56us (12.56us + 1us + 4us) So expected upper sampling rate is 56.9 ksps. Nyquist frequency for this sampling rate is therefore 28 kHz. If this is right, it suggests the (theoretical) performance suitability of this chip's A/D is for signals that are bandlimited to 28 kHz. Is this a correct interpretation of the information given in the data sheet in obtaining the Nyquist performance limit? Any opinions on the noise susceptibility of ADCs in PIC / dsPIC chips would be much appreciated! AKE

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  • dynamic char array sizing

    - by droseman
    Hello, In my application, I have a char array defined which can take one of three options: "okay", "high", "low" which are then sent down a serial port to a remote device. I currently have the array sized to take the 4 character words plus carriage return and line feed, but when I have to send "low" I get a null character in the strings, which I am concerned would confuse the host terminal. array definition char mod1_status_char[6] = {'0','0','0','0','0','0'}; char mod2_status_char[6] = {'0','0','0','0','0','0'}; char mod3_status_char[6] = {'0','0','0','0','0','0'}; sample of switch case statement: void DCOKStatus(uint8_t *ptr_status) { uint8_t status = *ptr_status; switch (status) { case 0x00: strcpy(mod1_status_char, "okay"); strcpy(mod2_status_char, "okay"); strcpy(mod3_status_char, "okay"); break; case 0x10: strcpy(mod1_status_char, "okay"); strcpy(mod2_status_char, "okay"); strcpy(mod3_status_char, "low"); break; } This is the struct which makes the message string to send strcpy(MsgStatus_on.descriptor_msg, "$psu_"); MsgStatus_on.address01 = hex_addr[0]; MsgStatus_on.address02 = hex_addr[1]; MsgStatus_on.space01 = 0x20; strcpy(MsgStatus_on.cmdmsg01, "op_en op1_"); strcpy(MsgStatus_on.statusmsg01, mod1_status_char); MsgStatus_on.space02 = 0x20; strcpy(MsgStatus_on.cmdmsg02, "op2_"); strcpy(MsgStatus_on.statusmsg02, mod2_status_char); MsgStatus_on.space03 = 0x20; strcpy(MsgStatus_on.cmdmsg03, "op3_"); strcpy(MsgStatus_on.statusmsg03, mod3_status_char); MsgStatus_on.CR = 0x0D; MsgStatus_on.LF = 0x0A; and this sends the message void USARTWrite(char *object, uint32_t size) { GPIO_SetBits(GPIOB, GPIO_Pin_1); char *byte; for (byte = object; size--; ++byte) { USART_SendData(USART1,*byte); } Would anyone be able to suggest a good approach to dynamically size the array to one character shorter when I need to send "low"? Thanks

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  • How I can fix this code to allow my AVR to talk over serial port?

    - by samoz
    Hi guys, I've been pulling my hair out lately trying to get an ATmega162 on my STK200 to talk to my computer over RS232. I checked and made sure that the STK200 contains a MAX202CPE chip. I've configured the chip to use its internal 8MHz clock and divided it by 8. I've tried to copy the code out of the data sheet (and made changes where the compiler complained), but to no avail. My code is below, could someone please help me fix the problems that I'm having? I've confirmed that my serial port works on other devices and is not faulty. Thanks! #include <avr/io.h> #include <avr/iom162.h> #define BAUDRATE 4800 void USART_Init(unsigned int baud) { UBRR0H = (unsigned char)(baud >> 8); UBRR0L = (unsigned char)baud; UCSR0B = (1 << RXEN0) | (1 << TXEN0); UCSR0C = (1 << URSEL0) | (1 << USBS0) | (3 << UCSZ00); } void USART_Transmit(unsigned char data) { while(!(UCSR0A & (1 << UDRE0))); UDR0 = data; } unsigned char USART_Receive() { while(!(UCSR0A & (1 << RXC0))); return UDR0; } int main() { USART_Init(BAUDRATE); unsigned char data; // all are 1, all as output DDRB = 0xFF; while(1) { data = USART_Receive(); PORTB = data; USART_Transmit(data); } }

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  • basic device that can connect to internet

    - by Hellnar
    Hello, I am looking for a cheap solution to my problem: I need to find either a common device (that is used in restaurants, bars clubs) or a cheap new device that can connect to internet (via the already existing ethernet or wireless based internet) and do HTTP request/receive response and retrieve information ? (For instance can a POS device connect to internet?) For a project, I need to do identity validation on several restaurants and bars and not all of them have computers. So I will be giving "cheap and easy to use devices" and non-IT personal can use it to do http request to my server and get response. All I can think of is Cell phones and SMS.

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  • Single database, multiple system dependency

    - by davenewza
    Consider an environment where we have a single, core database, with many separate systems using this one database. This leads to all of these systems have a common dependency, which ultimately introduces coupling between them. This means that we cannot always evolve systems independently of each other. Structural changes to the database (even if only intended for one, particular system), requires a full sweep test of ALL systems, and may require that other systems be 'patched' and subsequently released. This is especially tricky when you want to have separate teams working on different projects. What is a good 'pattern' to help in avoiding such coupling? I would imagine that a database should be exclusively depended on by one system. If other systems require data for whatever reason, they should request such from an API service of some kind. A drawback of this approach which comes to mind is performance: routing data between high-throughput systems through service calls is much slower than through a database connection.

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  • Declaration of arrays before "normal" variables in c?

    - by bjarkef
    Hi We are currently developing an application for a msp430 MCU, and are running into some weird problems. We discovered that declaring arrays withing a scope after declaration of "normal" variables, sometimes causes what seems to be undefined behavior. Like this: foo(int a, int *b); int main(void) { int x = 2; int arr[5]; foo(x, arr); return 0; } foo sometimes is passed a pointer as the second variable, that does not point to the arr array. We verify this by single stepping through the program, and see that the value of the arr variable in the main scope is not the same as the value of the b pointer variable in the foo scope. And no, this is not really reproduceable, we have just observed this behavior once in a while. Changing the example seems to solve the problem, like this: foo(int a, int *b); int main(void) { int arr[5]; int x = 2; foo(x, arr); return 0; } Does anybody have any input or hints as to why we experience this behavior? Or similar experiences? The MSP430 programming guide specifies that code should conform to the ANSI C89 spec. and so I was wondering if it says that arrays has to be declared before non-array variables? Any input on this would be appreciated.

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  • How to calculate a RTOS task's time

    - by Adnan
    Hello all, I have written a code in c for Arm7 using RTOS. There are multiple tasks who's priority is set to same level. So the tasks executes on round-robin base. There is an exception that one task (Default) has set to lower priority then the other task in rtos. So that if no task is running, the default or lower priority task runs. Now i want to calculate the exact total timing (time duration) for that default task runs. Can any one give some idea what to do .... and how to do in code.. Regards Dani

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  • Embedding a font in delphi

    - by ChuckO
    I'm working on an app that requires a particular barcode true type font that is unlikely to be on the user's PC. Can I somehow embed the font in the app, or do I need to use the installer to install the font?

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  • Linking the Linker script file to source code

    - by user304097
    Hello , I am new to GNU compiler. I have a C source code file which contains some structures and variables in which I need to place certain variables at a particular locations. So, I have written a linker script file and used the __ attribute__("SECTION") at variable declaration, in C source code. I am using a GNU compiler (cygwin) to compile the source code and creating a .hex file using -objcopy option, but I am not getting how to link my linker script file at compilation to relocate the variables accordingly. I am attaching the linker script file and the C source file for the reference. Please help me link the linker script file to my source code, while creating the .hex file using GNU. /*linker script file*/ /*defining memory regions*/ MEMORY { base_table_ram : org = 0x00700000, len = 0x00000100 /*base table area for BASE table*/ mem2 : org =0x00800200, len = 0x00000300 /* other structure variables*/ } /*Sections directive definitions*/ SECTIONS { BASE_TABLE : { } > base_table_ram GROUP : { .text : { } { *(SEG_HEADER) } .data : { } { *(SEG_HEADER) } .bss : { } { *(SEG_HEADER) } } > mem2 } C source code: const UINT8 un8_Offset_1 __attribute__((section("BASE_TABLE"))) = 0x1A; const UINT8 un8_Offset_2 __attribute__((section("BASE_TABLE"))) = 0x2A; const UINT8 un8_Offset_3 __attribute__((section("BASE_TABLE"))) = 0x3A; const UINT8 un8_Offset_4 __attribute__((section("BASE_TABLE"))) = 0x4A; const UINT8 un8_Offset_5 __attribute__((section("BASE_TABLE"))) = 0x5A; const UINT8 un8_Offset_6 __attribute__((section("SEG_HEADER"))) = 0x6A; My intention is to place the variables of section "BASE_TABLE" at the address defined i the linker script file and the remaining variables at the "SEG_HEADER" defined in the linker script file above. But after compilation when I look in to the .hex file the different section variables are located in different hex records, located at an address of 0x00, not the one given in linker script file . Please help me in linking the linker script file to source code. Are there any command line options to link the linker script file, if any plese provide me with the info how to use the options. Thanks in advance, SureshDN.

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  • GNU ld removes section

    - by Jonatan
    I'm writing a boot script for an ARM-Cortex M3 based device. If I compile the assembler boot script and the C application code and then combine the object files and transfer them to my device everything works. However, if I use ar to create an archive (libboot.a) and combine that archive with the C application there is a problem: I've put the boot code in a section: .section .boot, "ax" .global _start _start: .word 0x10000800 /* Initial stack pointer (FIXME!) */ .word start .word nmi_handler .word hard_fault_handler ... etc ... I've found that ld strips this from the final binary (the section "boot" is not available). This is quite natural as there is no dependency on it that ld knows about, but it causes the device to not boot correctly. So my question is: what is the best way to force this code to be included?

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  • Which Cortex-M3 interrupts can I use for general purpose work?

    - by Captain NedD
    I'd have some code that needs to be run as the result of a particular interrupt going off. I don't want to execute it in the context of the interrupt itself but I also don't want it to execute in thread mode. I would like to run it at a priority that's lower than the high level interrupt that precipitated its running but also a priority that higher than thread level (and some other interrupts as well). I think I need to use one of the other interrupt handlers. Which ones are the best to use and what the best way to invoke them? At the moment I'm planning on just using the interrupt handlers for some peripherals that I'm not using and invoking them by setting bits directly through the NVIC but I was hoping there's a better, more official way. Thanks,

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  • Running multiple applications in STM32 flash

    - by Richard
    Hey! I would like to have two applications in my STM32 flash, one is basically a boot and the other the 'main' application. I have figured out how to load each of them into different areas of flash, and after taking a memory dump everything looks like it is in the right place. So when I do a reset it loads the boot, all the boot does at the moment is jump to the application. Debugging the boot, this all appears to work correctly. However the problems arrives after i've made the jump to the application, it just executes one instruction (assembly) and then jumps back to the boot. It should stay in the application indefinitely. My question is then, where should I 'jump' to in the app? It seems that there are a few potential spots, such as the interrupt vectors, the reset handler, the main function of the app. Actually I've tried all of those with no success. Hopefully that makes sense, i'll update the question if not. thanks for your help! Richard Updates: I had a play around in the debugger and manually changed the program counter to the main of the application, and well that worked a charm, so it makes me think there is something wrong with my jump, why doesn't the program counter keep going after the jump? Actually it seems to be the PSR, the 'T' gets reset on the jump, if I set that again after the jump it continues on with the app as I desire Ok found a solution, seems that you need to have the PC LSB set to 1 when you do a branch or it falls into the 'ARM' mode (32 bit instruction instead of 16 bit instructions like in the 'thumb' mode. Quite an obscure little problem, thanks for letting me share it with you!

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  • SD card initialization SPI

    - by Openavr
    Hi People I saw a lot of infos about MMC/SD cards and I tried to make a lib to read this.. (modifying the Procyon Avrlib) But I have some problems here. I Don´t change the original code and tried here. My problem is about the init of SD card. I have 2 here, a 256mb and another 1GB. I send the init commands like this order: CMD0, CMD55, ACMD41, CMD1 But SD 256mb returns me only 0x01 response for each command.. the CMD1 i send a lot of times, SD 256mb always returs only 0x01.. never 0x00. The SD 1GB is more crazy... CMD0 returns with 0x01 ..nice but the CMD55 response with 0x05... another times responde with 0xC1... and another ones response 0xF0 with a 0x5F in the next interation... Around internet have infos and examples, but a bit of confused. Here in my project, I must use 1GB card and I´m trying with a MicroSD with a SD Adapter (I think that this is not the problem). Please any help are apreciate! Regards PS - my problem like the problem from this guy http://stackoverflow.com/questions/2365897/initializing-sd-card-in-spi-issues but his solution don´t solved my problem.. The SD1GB returns only 0x01 ever... :cry:

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  • STM32 Compiler/Debugger Chain?

    - by Nate
    I'm starting a project with a STMicro STM32. I've done the Google searches, looking for solid compiler/debugger chains but would prefer answers with success stories. Open Source Compilers/Linkers would be ideal, I just don't know if their STM32 toolchains are stable yet. (Both C, C++ compilers are acceptable). -- So commercial options are acceptable as well. Do any of you have useful suggestions?

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  • Flash Player - green box with version number

    - by Gavin
    I'm trying to get a very simple Flash video working using SWFembed, and it does work across multiple computers at this point in multiple browsers, but as soon as I pushed it live I got this: http://cl.ly/1EDS I've adjusted file permissions, but it is exactly the same code and files as in another directory on the server. I've seen this a few times (green box with version number), but have not been able to find any reference to it online. Thanks for any suggestions in advance!

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  • ARM cortex: mutex using bit banding

    - by Jeff V
    Given that, on the ARM Cortex M3, I can: atomically read a single bit atomically set a single bit atomically clear a single bit How can I combine these for a mutex style set of operations: try lock take lock release lock It seems that try_lock or take_lock would require two operations that would not be atomic. Do I need more control to accomplish this? Disable global interrupts would do it but it seems there should be a more surgical approach.

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  • Accessing the MSP and PSP registers of the Cortex-M3 in C/C++ code using Keil's µVision

    - by Captain NedD
    I need to access the MSP and PSP registers (the main and process stack registers) of the Cortex-M3 processor. I'm writing in C/C++. The µVision and associated compiler doesn't let you do inline assembly for this Thumb-2 only core (and I'm not sure that'd be such a good idea anyway). I need to do this so that I can extract the immediate value of an svc instruction regardless of whether it was executed while in thread or handler mode. Thanks,

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  • How to make a product catalog in C#?

    - by Ervin
    I need to develop a product catalog (about 4000 products) application, which would be given to clients on CD or DVD. The catalog exists in webpage format using PHP and MySQL. IMPORTANT: the application is given to clients who maight have old PC, old System. For minimal requirements I would put Windows XP and Internet Explorer 6 (if needed). I need the following features: 1 search option (after productID AND after keyword) 2 print option (by selecting multiple products) 3 shopping cart (making a list which will be sent to an email address if there is any Internet Connection on the computer) When I was asked to do it I had 2 days to realise a very basic version, so I took the whole website and exported it in HTML pages, and developed an application in C# which contains an embeded browser. So the whole website is now static and put on a CD. Everything fine so far. Now here are the problems: 1. the search option was realized by parsing the html files and reading the productID or looking for keywords inside of them. Put on a CD it was extremely slow (searching in 600MB of html files). FOR THIS I WOULD NEED A SOLUTION WITH A STATIC DATABASE (USING ACCESS OR SOMETHING) TO HAVE INDEXED ROWS, SO THE SEARCH COULD BE A VERY FAST ONE. 2. the printing option was a simply call of the embeded Internet Explorer print functions. Here are two problems: a) user needs IE7 for printing the website scaled (FIT TO PAGE), otherwise the edges of the page are cut down. b) users of this app does not have even the basic PC usage skills, so they can't set the printing settings, so there will appear in header and footer the page numbers and titles. QUESTION: can I set these settings from CSS for printing? 3. couldn't make a a shopping cart as I don't use a database, so I have static websites and content is inside the HTML. QUESTION: WHICH ARE THE BEST SOLUTIONS FOR THE PROBLEMS DESCRIBED ABOVE? PLEASE ANSWER EVEN IF YOUR ANSWER IS FOR ONE QUESTION ONLY. THANKS

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  • GUI-Library for microcontroller

    - by Martin Kirsche
    I want to create a GUI driven application for a micro-controller (Atmel XMEGA) that is connected to a 128x64 dots graphics LCD (EA DOGL128-6) and 4 buttons for navigation. Controlling the display itself (e.g. drawing pixels and characters) is no problem but in order to prevent me from reinventing the wheel I was googling for a GUI-Library/-Toolkit that is written in c, includes its source code, will run on a 32 MHz 8-bit micro-controller and provides at least the following controls: panel (to group elements) menu (scrollable) icon label button line-graph (optional) But I didn't find any thing useful. Does anyone know (or better uses) such a library(preferably for free)?

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  • AVR Analog Comparator + Internal Pullup?

    - by vicatcu
    I have what I hope is a simple question pertaining to the Atmel AVR microcontrollers. So I want to use the ATTiny85's Analog Comparator to determine if a signal is above or below a threshold. This signal is normally "floating" and grounded when "active" (i.e. it's an active low - open collector signal). If I enable the pullup on the input pin (which is also the comparator input) by doing: DDRB = 0x00; // DDRB.1 = 0 = input PORTB = 0xFF; // PORTB.1 = 1 = internal pullup enabled If i use the analog comparator and select PORTB.1 as AIN1 will the internal pullup be applied to my input signal? I'm hoping someone has personal experience to verify this behavior. Hope this question isn't too 'hardware-oriented' for stack-overflow. Thanks!

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  • Only allow access of FIle From embed.

    - by KyleT
    Hey All, So I am embedding a PDF file on my page: <embed src="http://www.mywebsite.com/files/ebook.pdf" width="500" height="375"> Is there anyway to prevent any and all access to that file except for when it is being accessed via this embed? Thanks!

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  • Linux USB debug connection to LuminaryMicro evaluation board

    - by mikelong
    Hi, I am trying to connect a Stellaris LM3S8962 evaluation kit to a linux host machine. I am using the CodeSourcery G++ for the development toolchain. When I try to run a helloworld example the connection fails with this message: arm-stellaris-eabi-sprite: error: E104. I/O Error communicating with USB Device. arm-stellaris-eabi-sprite: waiting for GDB connection, to pass error along warning: Remote failure reply: E.fatal.E104. I/O Error communicating with USB Device. arm-stellaris-eabi-sprite: error: E002. Not initialized When I connect the evaluation board with the USB cable it seems the device is made available to the system: Mar 24 14:37:16 n6-ws2 kernel: usb 5-2: USB disconnect, address 5 Mar 24 14:37:18 n6-ws2 kernel: usb 5-2: new full speed USB device using uhci_hcd and address 6 Mar 24 14:37:19 n6-ws2 kernel: usb 5-2: configuration #1 chosen from 1 choice Also, it seems that I can connect in some way via the command line tool (but I do get some strange characters): [mlong@n6-ws2 bin]$ ./arm-stellaris-eabi-sprite -i CodeSourcery ARM Debug Sprite (Sourcery G++ 4.4-104) armusb: [speed=] ARMUSB device armusb:///?? - ?? (??) Does anyone have any suggestions I could try? Thanks a lot, Mike

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