projects:sysmon
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projects:sysmon [2016-01-24 16:07] robert added pictures |
projects:sysmon [2016-02-03 11:34] (current) admin |
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| ==== Circuit and Components ==== | ==== Circuit and Components ==== | ||
| The system monitor is built around a [[http://www.microchip.com/wwwproducts/Devices.aspx?product=PIC16F1455|PIC16F1455]] - a 14-pin microcontroller with a USB device peripheral and two PWM channels, which is exactly what is needed for this application. | The system monitor is built around a [[http://www.microchip.com/wwwproducts/Devices.aspx?product=PIC16F1455|PIC16F1455]] - a 14-pin microcontroller with a USB device peripheral and two PWM channels, which is exactly what is needed for this application. | ||
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| + | {{ :projects:sysmon.png?direct&600 |}} | ||
| + | <WRAP centeralign> | ||
| + | //Schematic of the system monitor.// | ||
| + | </WRAP> | ||
| The two PWM outputs of the PIC are used to drive the meters. In order to get a nice DC voltage for driving the meters, the PWM is first passed through as simple RC lowpass. Because the RC time constant is quite slow (~300ms), the response of the meters is also slowed sown a little, which I find visually more pleasing than an instant response. This DC voltage is then buffered by a LM324, and applied to the meter through a series resistor. The purpose of the series resistor is to scale the 0-3.3V range of the PWM output to the 0-100mV range of the meter. | The two PWM outputs of the PIC are used to drive the meters. In order to get a nice DC voltage for driving the meters, the PWM is first passed through as simple RC lowpass. Because the RC time constant is quite slow (~300ms), the response of the meters is also slowed sown a little, which I find visually more pleasing than an instant response. This DC voltage is then buffered by a LM324, and applied to the meter through a series resistor. The purpose of the series resistor is to scale the 0-3.3V range of the PWM output to the 0-100mV range of the meter. | ||
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| Apart from that, there is not much else to the circuit: A LED shows the USB status, and several headers on the board provide for USB, ICSP and meter connections. The USB connector on the outside of the case is a [[http://www.farnell.com/datasheets/1699375.pdf|Bulgin PX0443]] Mini-USB to Molex KK assembly. | Apart from that, there is not much else to the circuit: A LED shows the USB status, and several headers on the board provide for USB, ICSP and meter connections. The USB connector on the outside of the case is a [[http://www.farnell.com/datasheets/1699375.pdf|Bulgin PX0443]] Mini-USB to Molex KK assembly. | ||
| - | ==== Firmware ==== | + | ==== Firmware and PC Software ==== |
| - | <WRAP center round info 60%>github repo coming soon</WRAP> | + | |
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| - | + | ||
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| - | ==== PC Software ==== | + | |
| The system monitor hardware is simply a box with two panel meters that shows values sent via USB. All the magic that turns it into a system load monitor is in the Python script that controls it. | The system monitor hardware is simply a box with two panel meters that shows values sent via USB. All the magic that turns it into a system load monitor is in the Python script that controls it. | ||
| - | I believe the software is pretty self-explanatory: It uses [[https://pypi.python.org/pypi/psutil|psutil]] to get the system information and sends it out to a specified (virtual) serial port. Since the firmware uses custom manufacturer and device ID strings, it is possible for the script to auto-detect the system monitor under Linux. Annoyingly, this doesn't work under Windows, because Windows insists on an INF file from which it reads the device ID strings (despite it being a CDC device). The whole trouble of a custom VID and PID and getting a signed INF is just not worth it, but I might look into a more active way of identifying the system monitor (''*IDN?'', anyone?) | + | I believe the PC software is pretty self-explanatory: It uses [[https://pypi.python.org/pypi/psutil|psutil]] to get the system information and sends it out to a specified (virtual) serial port. Since the firmware uses custom manufacturer and device ID strings, it is possible for the script to auto-detect the system monitor under Linux. Annoyingly, this doesn't work under Windows, because Windows insists on an INF file from which it reads the device ID strings (despite it being a CDC device). The whole trouble of a custom VID and PID and getting a signed INF is just not worth it, but I might look into a more active way of identifying the system monitor (''*IDN?'', anyone?) |
| - | <WRAP center round info 60%>github repo coming soon</WRAP> | + | The firmware running on the PIC is a very slight modification of Microchip's CDC demo project, which accepts messages containing numeric values and sets the PWM outputs accordingly. Again, it should be pretty self-explanatory once you take away the code that implements the CDC device. |
| + | The GitHub repo containing the firmware and PC software is located [[https://github.com/kitsune-denshi/sysmon|here]] | ||
| ====Pictures==== | ====Pictures==== | ||
projects/sysmon.1453662444.txt.gz · Last modified: 2016-01-24 16:07 by robert
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