![]() ![]() Serial ports is at worst case below 40 µs at onboard ports and port on PCI(e) cards.įor writing the log file to the disk periodically there is also a flushing thread. Typically every 34 µs under a Linux Kernel with the Preempt-RT patch. The program uses one thread per input because select() and pselect()Ĭan not handle more than one port with i) low latency and ii) correct order of the incoming bytes.įor orthogonality there is also a timer thread which triggers the parallel reading threads periodically, the output of an analog to digital converter (ADC). With a direct port access to toggle an output pin before every read access it is easy to read converted data synchronous,Į.g. Ioctl() with a higher latency but good portability. With direct port access for a low latency of about 1.5 µs or the 4 input pins of a serial port with )ī) a transient recorder/digitizer, for logging parallel data from the input pins of serial ports and/or parallel ports, Multithreaded_logger is a C program and a hybrid ofĪ) a logging program which logs serial data (RS-232, -422, -485, CAN, Ethernet. In the subdirectory doxygen/working/, and the output is placed in the subdirectoryĭoxygen/output/, via "doxygen doxygen/working/Doxyfile". The documentation is generated with the configuration file Doxyfile There are MOSFETs which can perform the switching function while inserting only a few milliOhms resistance.Project multithreaded_logger, logging of serial and/or parallel data, with defragmentation Program multithreaded_loggerĬurrent source code: multithreaded_logger.c. You could do this electrically, but there must be a short delay between the time the supply connection is opened and the connection to the LED made. You would also have to disconnect the supply from the capacitor prior to pulsing the LED. If the LED resistance is the greatest, then calculating the necessary time constant can be done using the formula: t = RC. Discharging to around 10% of the initial capacitor voltage requires 2 time constants of 500 ns each. For example, if you did this repetitively, you might damage the LED, capacitor, or both.Īlso, in order to fully discharge a capacitor, you need a low impedance electron path or a very small value capacitor. This probably won't happen within 1 us, and if it did, would cause problems under normal circumstances. If you want to discharge a capacitor into an LED quickly, the most significant factor is LED resistance contribution. So unless there is something very exotic about the load or the switching circuit connecting it to the capacitor, ESR won't matter at all. And because no frequency has been specified (only a pulse duration), the discharge time constant would be primarily set by the LED. There really should be no need to be concerned about capacitor ESR for a pulsed discharge circuit as described. That helps to get you the most accurate answer. It always pays to give as much accurate information as possible. I get the feeling that something crucial to giving a good answer wasn't stated because ESRs of most electrolytics are below 1 Ohm, which will have little or no impact on the given circuit. Any switching mechanism (which may have its own set of impedances) must be assumed because nothing is specified. If the discharge is repetitive, the circuit response may differ. If the supply voltage is very close to the forward voltage drop of the LED, ESR may be an issue, but that would depend on the capacitance of the storage capacitor and supply resistance. ![]() ![]() A 1 us draw of charge from a charge storage capacitor is nominal, so the storage capacitor will maintain most of its charge after a single cycle. #Parallel to serial converter rc net word seriesSo unless there is a current limiting resistor in series with the LED, the discharge time constant will be mostly determined by the LED forward voltage and the power supply resistance. #Parallel to serial converter rc net word plus
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