embedded

I have an embedded application with a time-critical ISR that needs to iterate through an array of size 256 (preferably 1024, but 256 is the minimum) and check if a value matches the arrays contents. A bool will be set to true is this is the case. The microcontroller is an NXP LPC4357, ARM Cortex M4 core, and the compiler is GCC. I already have combined optimisation level 2 (3 is slower) and placing the function in RAM instead of flash. I also use pointer arithmetic and a for loop, which does down-counting instead of up (checking if i!=0 is faster than checking if i<256 ). All in all, I end up

I am developing an application in VBA. Userforms connect to a COM object that reads an SPSS Statistics SAV file or an SPSS Dimensions MDD file. Part of this application stores metadata in an XML document so that we can retrieve the metadata later and repopulate or update the graphics created from the userforms. This works fine as long as we rely on an XML file existing on a local drive - which is not a desirable solution. We would prefer to embed (not link) the XML in to the PPTM file, which I have been able to do (see attached). The problem is that I can't find a way to get VBA to extract the

I know basic SPI protocol and its master to slave operations. I want to know that is it possible to broadcast data on multiple slave? If it is possible then how it works. I've heard that after writing to any SPI slave you have to read from slave even if you are not going to use read data. How is this possible in case broadcast if broadcast is possible? No, it's not possible. Since SPI is 4- wire interface. The SS line is used for slave selection.One SPI master can have multiple slaves but it cannot select all the slaves at once since it is either using some bit or SS signal to select the slave

I have an ethernet library for microcontroller (keil rl-tcpnet for lpc2478). Library uses va_list (standard pointer to arg array macro defined in stdarg.h) in debug output function in such a way: void __debug__ (const char *fmt, ...) { va_list args; va_start (args,fmt); vprintf (fmt,args); va_end (args); } However vprintf sends data to incorrect stream and I need to redirect debug output of library to correct serial port. Library has .c cofigure files and I write c++ code so I use wrapper function pointers to call c++ style code from c code. So I rewrite this function: extern void (*

I think I'm thinking about this the wrong way, but I'm wondering how an embedded system with less than 32-bits can use 32-bit data values. I'm a beginner programmer so go easy on me :) base 10 0100 <- carry in/out 5432 +1177 ====== 6609 never brought up in class but we can now extend that to two operations 100 32 +77 ====== 09 01 54 +11 ====== 66 and come up with the 6609 result because we understand that it is column based and each column treated separately. base 2 1111 +0011 ===== 11110 1111 +0011 ===== 10010 110 11 +11 ===== 10 111 11 +00 ===== 100 result 10010 you can break your operations

I have a uint64 variable which often only requires high or low 32 bit access. I am using a 32-bit ARM Cortex M0, and to help with speed and I am trying to overlap the uint64 variable with two uint32 variables in C, using anonymous structures in the hope of avoiding pointer arithmetic to access members. Is what I am trying to do possible? It could be that using a named union is just as fast, but now I'm just intrigued if it can be done without. The following does not compile successfully: http://goo.gl/ejx37y #include <stdint.h> volatile union { uint64_t ab; struct { uint32_t a, b; }; }; int

I am trying to embed tslib on an ARM system, in order to use a touchscreen device ; I already installed it successfully but unfortunately I can't retrieve all my notes to do it again. x) I cross-compiled the libraries files, and I put them into /usr/lib ; I have created the conf file /etc/ts.conf and I have exported the good environment variables : export TSLIB_TSDEVICE="/dev/event2" export TSLIB_CONFFILE="/etc/ts.conf" Here is my problem : tslib doesn't seem to create the event device when I plug the device in. And here is the result of *ts_calibrate* : ts_open: No such file or directory I