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Test & Tools

49 Posts authored by: Jan Cumps Top Member
I have a ST Micro Nucleo board with a low power microcontroller. The STM32F030R8 I'm going to measure its power consumption, to see how well it would do in low power designs. ST has a good power measurement example; called PWR_CurrentConsumption. It allows to measure power in SLEEP, STOP and STANDBY mode. This blog shows the power in the different modes.   Probe Point  The Nucleo 64 boards have a jumper called IDD. It's in the direct current path to the controller. You can replac ...
This real world example shows how to trigger a RIGOL DS1054Z oscilloscope at a specific point in an i2c communication, and then check signal + data. The DS1054Z comes with i2c functionality. In the past they were options you bought separately. Since 2019 they are standard.     Test Setup and Hooking up the Oscilloscope  Any i2c setup will do. Just pick whatever design you have that uses the protocol. I used a very simple design: An Arduino UNO talking to an RGB + ir sensor fr ...
A small script for the DMM6500 to take a number of measurements, triggered by an external signal. This can be useful when you're automating a test setup. On a production line, on a binning desk, in a setup with a foot pedal, ... I've deliberately kept the script as simple as possible, to make it easy to grasp. You get a lot of functionality with just 8 lines of code.   Let's get straight to business. The TSP code: buffer_size = 10 app_buffer = buffer.make(buffer_size, buffer.STYLE_ST ...
A little bit of nostalgia: my Philips power supply. 3 channels. Isolated. Constant voltage and constant current. And perfectly silent - no spinning fan. Made in Belgium! click to enlarge   Over here, Philips was the go-to brand for lab instruments. When I studied electronics, every instrument - except some Kyoritsu meters - was a Philips. In my own lab, this supply and a Philips oscilloscope were the pièces de résistance. I've sold the scope. I still use the power su ...
I'm thinking about building a low power SMU. We're playing with OpAmps and discrete semiconductors regularly over here, and there's a Keithley 2450 SMU with I-V Tracer Software  road test going on. Learnings from those activities can be applied here.   image: over simplified concept   Goals: Only two; Make a Source Measure Unit. Make it programmable or scriptable   Possible capabilities: This would be a low power instrument, µA up to maybe a few mA. Low voltage ...
I wrote a blog in 2015 about using an FPGA as logic analyzer. In that blog, I promised to review the input buffer that I was using to translate 5V logic to 3V3. Then I didn't follow up on that.     Yesterday I made a second buffer, using parts and PCBs that I had lying around from a few failed previous attempts. A good excuse to finally document this.   What Is This Input Buffer?  The inputs of my analyzer are raw Xilinx Spartan 6 FPGA I/O pins. They aren't 5V tolerant ...
Detailed review of the current shunt circuit of the Programmable Electronic Load. The circuit and measurements are discussed here.   Circuit  The current measurement circuit reads the voltage over a 50 mΩ shunt resistor that's in series with the load circuit.   That voltage (always negative, because the resistor is "below" the circuit's analog ground) is amplified by a non-inverting OpAmp circuit, with gain 7.8.   Test Setup  A DMM measures the voltage of th ...
LabVIEW 2020 Community Edition has just been released (yesterday on the day I type this). I was part of the Beta test team. To celebrate the release, a flow to characterise a lab instrument: use a power supply and a digital meter to validate a DC load. Instruments used: PSU: Rigol 832A DMM: Keithley DMM6500 device under test: our eLoad. I made this LabVIEW flow because I needed it, not for this blog. But maybe that's an asset. It's a real flow. And it's not hard to adapt this to other ...
I'm building a GUI for the electronic load we made here on element14. The development will be in a few incremental steps. This is the second iteration: add error logging make the LCD display emulation work a few dedicated controls to set current and enable / disable input   Retrieve Instrument Status: Multiple SCPI Commands Combined  The screen refreshes the GUI controls based on the instrument status. LCD display displays mode, set current, measured current and voltage, inpu ...
I'm building a GUI for the electronic load we made here on element14. The development will be in a few incremental steps. communication with the instrument basic GUI with a SCPI command line and results In the next iterations: add error logging make the LCD display emulation work a few dedicated controls to set current and enable / disable input   Functionality in the 1st Iteration  The application has its basic layout and one function implemented. I want to start with a lay ...
My electronic load failed. In this second post, I test the remaining parts of the DAC/ADC board.   Tests Approach  The eload DACs and ADCs are on a separate PCB, together with the voltage reference and the I2C isolator. The voltage reference isn't damaged. I've tested that in the previous post.   All DAC outputs and ADC inputs are broken out to the connector at the low side of the board. The load's firmware has low level SCPI functions that can directly talk to the convert ...
My electronic load failed. I was trying new hardware and software options. At a certain moment the power MOSFET died. There was no magic smoke, but the source, drain and gate are all shorted (source, drain and gate all measure a few Ohms in both directions). I am not 100% sure of what has happened, but I think that a bad contact at the gate or current sense resistor, while the FET was supplied with 40 V, did it. No sound, no smell. Just an instantaneous death. In this post, I'm checking what ...
I'm designing a low power IoT in the Cloud framework for the Arduino MKR WIFI series. A firmware proof of concept that uses the low power option of this Arduino as much as possible, only to wake up to make a measurement and beam it to Amazon Web Services (AWS). The framework also reports the battery state. This allows the operator to go charge the battery before the defice runs out of juice. This blog measures the solution's power consumption over long time. It takes in account the time spe ...
Now that I have a programmable psu, dc load, oscilloscope and multimeter, it's time to build a flexible test bed. It's main purpose is to specify efficiency of switch mode regulators. But with some tweeking itcan also be used to measure ripple of a power supply under load. It's going to be a flow that can step through voltages, then sweeps the load over a range,makes measurements and log them to a spreadsheet. The flow will be able to loop this process once, or continuous until the STOP bu ...
I'm road testing the  Keithley Bench Digital Multimeter DMM6500. In this post, a simple method to save measurements and list them in a table with a keypress.     Saving Measurements to a Table  This is the default behaviour of the DMM. Measurements are stored in defbuffer1 when you switch on the meter. I'm using this functionality to register a number of measurements, using the TRIGGER button to take a measurement.   I'm measuring a feedback circuit on my bench. ...

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