Voltmeter families. Dual-channel meas-urement and readout: left channel in dBm, right channel in mW; bargraph allocated to left channel Readout of correction frequency (see also under 'Measuring heads') together with measured value Readout of pulse power after entry of duty factor Readout of modula-tion depth of an am-plitude-modulated signal.
![Dual Channel Voltmeter Pic16f876a Dual Channel Voltmeter Pic16f876a](http://www.kswichit.com/DVM7135/102_7975.jpg)
5 September 2011Connectingthe Voltmeter to a PCThe new firmware providesa means to connect the Voltmeter to a PC using RS232C. Student may usesa PC running terminal emulator program for data logging easily.We can use thefor connecting the Voltmeter. For a notebook without the RS232 port, wecan use the RS232-USB converter cable.Figure11:RS232 to USB converter.Run the PuTTY, it will askfor selecting the session. Select Serial port and set the COM port number.Figure12: Select session to Serial interface.For more options, click atSerial under SSH, select the flow control to None.Connect the cable to a givenport, says USB or direct COM port.Click Open, the screen terminalwill be appeared, press ENTER key followed with? For help menu.Figure13: Help menu display.There are three commandsas follows.1. Command 'a' prints thereadings to the terminal with a programmable interval automatically.2.
Command 'i' sets theinterval between sample to print using command 'a'. Default is 1 second.3. Space bar hitting getsthe readings from both channels and wait for user entry the numeric data.The example of using command'a' and command 'i' is shown in Figure 14.Figure14: Print the readings to terminal automatically.As shown in Figure 15, wecan set the terminal to capture the printable text on the screen to a datafile. PuTTY calls it as the LOG file.Figure15: Setting LOG filename and session logging.Go to Session-Logging, click at Printable output and type the filename. The example shown in Figure 15 uses Year, Month, Date to be the filename for easier finding the files.For experiment that needsstudent to enter another variable at a given event, we can use space barhitting with manual entry.When the Space Bar was hit,the readings will appear on the screen and user can enter the numeric datawith Enter key.
For next sample, hit Space Bar again.Figure16: Event with entry mode.When the session was closed,we will get the log data file as shown in Figure 17. The file is text filewith comma separated value, thus it can be imported into the spreadsheetsoftware easily.Figure17: Log file content.Download,What's New?
Date: december 1999AbstractThis paper describe a dual channel digital volt meter builded arounda PIC16F84. It uses a 20 characters dual lines LCD display and a dual channel12 bit serial AD converter.
Actually the SW display only a number proportionalto the input voltage (5 V = 4096) and it's better to add some op-amp withlittle gain so that you can read 4096 (mV) with 4.096 V at the input. Withsome SW and HW add-on it can be useful as voltage/current/power meter forpower supply, as SWR meter with direct and reverse power indication andfor other tasks where you have to measure two electrical signals (and perhapscompute some other parameter). It's easy to add another A/D converter fora 4 channel DVM. RS-232 serial interface can be added. Search the WEB forPIC SW tips and tricks.