Owon XDM1041 DMM

Posted on December 1, 2025 by David Albert

I have generally had good experiences with Owon’s USB oscilloscopes and decided to try their low-cost bench DMM, the XDM1041. It is a 4.5 digit, 55K count DMM, so it’s not going to displace anyone’s 6.5 digit Keysight or Keithley, but it is cheap (under $100 on AliExpress), small, AC-powered, has a lovely display, and perhaps most importantly has a USB SCPI interface so you can use it for test automation (note: you cannot power the DMM via the USB port). The version I have is AC-powered, but it’s also available with a battery option (XDM1241) for portability; otherwise, the two models are spec’d the same. There are lots of comprehensive reviews; a particularly good one is here: https://www.youtube.com/watch?v=xzsmyjWFtW8 (defpom); here’s a teardown. I’ll try not to reproduce what’s there but rather will focus on adding details or exploring features rarely covered.

Frequency Counter

I wanted to test the frequency counter myself because most reviews don’t provide enough analysis of the voltage required for the counter to operate at any particular frequency:

The counter as advertised as working up to 60MHz. Obviously the 4.5 digits creates an inherent limit to the resolution, but it’s accuracy is advertised as 0.2% + 10 counts. I tested using a 120MHz SDG-2122X AWG slaved to a DOCXO (very stable/accurate) external frequency standard. The AWG was generating a sine wave and was connected to the DMM via a 1m RG59 cable and a BNC-to-banana adapter on the DMM (I think this is the same adapter used in the defpom video). I’ve documented the readings and the minimum voltage required for a stable reading below:

View frequency accuracy vs. required voltage table

AWG	DMM Counter	Min Vpp
55kHz	54.998kHz	1.5
100kHz	99.997kHz	2.0
550kHz	549.98kHz	2.0
1MHz	999.97kHz	2.0
5.5MHz	5.4998MHz	2.5
10MHz	9.9997MHz	2.5
16MHz	15.999MHz	3.3
25MHz	24.999MHz	3.3
30MHz	29.999MHz	3.3
40MHz	39.999MHz	3.3
55MHz	54.998MHz	3.6
60MHz	59.998MHz	3.6

The DMM requires a fairly strong signal; even low frequency signals required at least 1.5 Vpp. That said, and much to Owon’s credit, the frequency accuracy is well within spec and fairly good for a devices whose timebase is just an XO. Consider the 1MHz reading: 0.2% is 2kHz and the actual reading (999.97kHz) was within 30Hz so the frequency performance dramatically exceeds the spec.

The primary limitations appear to be the requirement for a strong signal and the counter resolution of 4.5 digits. If testing a 16MHz crystal oscillator, 4.5 digits limits each count to 1kHz or 62.5ppm. This might be good enough for confirmation of oscillator operation, but is insufficient to confirm operation within the specs of a +/-20ppm or even a +/-50ppm crystal.

SCPI and DC current measurement

I tested the SCPI interface which uses the USB connection to a Windows 11 computer. The port enumerated as a serial interface (CH340) and uses 115kbps 8/N/1. I tested using TeraTerm as the serial interface program. I wanted to see if I could use the DMM to provide accurate current measurements for some test automation (short answer: yes, it works great)

*IDN? (returns “OWON,XDM1041,2212364,V3.3.0,3”)
CONF:CURR:DC [500E-3 | 500E-6] -3=500mA, -4=50mA, -5=5mA, -6=500uA
FUNC? (returns “CURR” (with quotes))
RANGE? (returns range e.g. “500 uA”
AUTO? (returns “1” if in auto-scaling mode, “0” for manual)
MEAS? (returns current in scientific notation: “1.557310E-05”)

GW Instek PSP-2010

Posted on September 13, 2025 by David Albert

I have several bench supplies, but one that I am fond of is the Instek PSP-2010. As one might guess from the title, it’s a 0-20V, 0-10A 200W supply. It has a fan, but it stays off unless under heavy load.

Pros: solid build: metal chassis with carry handle. Output is quiet: the switching is well filtered. Very clean startup and shutdown: many low/moderate cost bench supplies have voltage spikes when you turn the output on or off; this one is clean, even with a significant inrush load current spike as shown below. The voltage setting and current limit are accurate and it has a CV, CC, and CW modes. The current display goes to 3 decimal places and while it claims to have only 5mA resolution, mine seems to have 2mA. The voltage display resolution is 10mV; mine reads about 60mV high at 6V (i.e. it’s pretty accurate).

Cons: although it has a keypad, you can’t directly enter voltages and currents, you have to use the encoder wheel. It’s not terrible, it has buttons to select fine and coarse adjustment so it’s easy to get to the setting you want, but a full 0..9 keypad would be a really nice addition. The other con is the use of a DB9 serial connector for PC connectivity. C’mon guys, it’s not 1995…USB please.

Repair: I use this daily and recently, when I went to turn the output on, the relay started to chatter and there was no output (i.e. it was failed). I was bummed and was getting ready to toss it, but as usual, eevblog came through. It turns out that there are two 470uF electrolytic capacitors in this supply (C25, C29) that commonly fail and when I opened mine up (6 screws and the cover lifts straight up), sure enough, those caps were bulging (see photo). I removed the board (4 corner screws plus a plastic locking standoff near the middle) and removed the caps; one measured 4.7uF, the other measured 14.6uF. I replaced them with Digikey P12389-ND, retaining the insulating standoffs from the old caps, and the supply works like a champ again!

Hacking Oscilloscope Bandwidth

Posted on June 16, 2024 by David Albert

The price of oscilloscopes goes up quickly above 100MHz bandwidth, often placing them out of the budget of hobbyists and small businesses. The analog bandwidth of a scope is defined as the frequency at which amplitude is reduced by 3dB (roughly 30%)

Most oscilloscope lines offer a variety of bandwidth options (at increasing prices) such as 50, 100, 200MHz or 100, 350, 500MHz. In many cases, those are really the exact same scope hardware (the highest bandwidth) but are limited in software to a lower bandwidth. This allows manufacturers to address a broader range of potential customers (they can sell the 100MHz scope to individuals or small companies without undercutting the big margins of their 500MHz scope sales to large companies).

Some manufacturers have made it possible for hobbyists to unlock the higher bandwidths. Doing this voids any warranty or calibration of course, and so most labs or large companies simply won’t do this and if you choose to do it, it’s at your own risk. However, I have done this successfully with scopes from Siglent (SDS1104X) and Tektronix (TDS3xxx) and the results have been pretty good.

TDS3K scopes are older Tektronix models that used to cost a fortune (Tek was long the king of the oscilloscope hill and my favorite). The TDS3K line came in 100, 350, and 500MHz models. Fortunately, you can hack any TDS3K scope to 500MHz. For info on how to do this, look to the always excellent eevblog (here). Note that you will need to downgrade the firmware to 3.39 in order to perform the hack. In a nutshell:

Install a communications module in the back slot
Configure for 9600,8,N,1 (local echo on is helpful)
Check current version: *IDN?
PASSWORD PITBULL
MCONFIG TDS3052 (or whatever model you’re upgrading to)
Reboot the scope

Note too that there are downsides to the TDS3K line like calibration is stored in battery backed RAM (and the battery will eventually die). In general, to continue to use a scope of this age, you should plan to re-cap it (replace all electrolytics) and replace the battery-backed RAM module with a new one.

Siglent and Owon are Chinese companies that make a lot of test gear that isn’t quite up to Tek or Keysight standards, but still offer a great deal of bang for the buck and the Siglent products are often hackable. For info on how to hack the Siglent SDS110x scopes you can also refer to eevblog.

An important question is: how do these scopes perform after the hack, so I tested a Tektronix TDS3012 (100MHz) before and after hacking it to a TDS3052. I also tested a TDS3032 I had previously hacked to TDS3052, a Siglent SDS1104X hacked from 100 to 200MHz, and compared them with an unhacked TDS5054B (500MHz) and an Owon SDS8202 (200MHz). In each case I supplied a 0dBm tone from an IFR 2025 RF signal generator through an admittedly less-than-ideal but short coax cable with BNC connectors. For the scopes without internal 50-ohm termination, I used a BNC through terminator and a 6dB attenuator.

A 0dBm signal terminated in a 50R load should be 632mV peak-to-peak. At the bandwidth limit of the scope, that signal should be reduced by 3dB or roughly 30% (-3dBm = 448mV p-p):

MHz:	Term	10	50	100	200	300	350	400	500
TDS3012 (before hack)	Int			562	320	—	—	—	—
TDS3012 (hacked)	Int	666	648	644	640	606	580	554	510
TDS3032 #1 (hacked)	Int	680	665	660	644	630	604	578	530
TDS3032 #2 (before hack)	Int	641	627	626	598	563	546	511	457
TDS3032 #2 (hacked)	Int	658	640	637	631	619	604	576	555
TDS5054B	Int	662	642	630	627	593	575	560	566
SDS1104X (hacked)	BNC	650	638	600	514	360	264	169	57
SDS8202	BNC	680	672	664	608	512	424	300	—

Peak-to-Peak voltage measured with 0 dBm sine wave

It’s clear that the hacks really do increase the available bandwidth. In the case of the TDS3K scopes, to greater than 500MHz, making them truly the equivalent of TDS305x. I measured a 700MHz signal on a hacked TDS3032 at 466mVp-p so the 3dB bandwidth was even higher than that! The hacked scopes also show the sample rate at 5Gs/s whereas before the hack they top out at 1.25 or 2.5GS/s.

The Siglent SDS1104X (nominally 100MHz) hack also extends its bandwidth to 200MHz; mine was down -1.78dBm at 200MHz and still slightly better than 3dB at 235MHz (-2.88dBm). The trigger was able to lock cleanly out well past 400MHz and measurements remained accurate. Note: the SDS1104X does not offer internal 50R termination so measurements were made through a 6dB pad (reduces signal by half, probe set to 2x) and 50R through terminator.

The old Owon SDS8202 (nominally 200MHz) did remarkably well out past 300MHz, easily outperforming the hacked SDS1104X. Owon makes nice analog front ends! Note that frequency measurement stopped at 200MHz even though the scope was clearly able to trigger on and lock to signals out to 400MHz.

Siglent

Posted on October 17, 2023 by David Albert

For decades, lab-grade test equipment came from either HP or Tektronix. There were other providers in niche areas (R&S, Anritsu, IFR, etc.), but nearly all lab-grade gear was too expensive for mere mortals. With few alternatives, hobbyists and small businesses scrounged eBay and corporate liquidations to find used gear from these manufacturers.

Times have changed and while those companies still make great test gear, the competition from China has steadily improved and in many (most?) cases, it makes more sense to buy new gear from a budget Chinese manufacturer than 20-40 year old big-name gear.

I’ve bought (and liked) products from Rigol and Owon, but my budget manufacturer of choice is, increasingly: Siglent. My recent purchases include:

SDG2042X – 40MHz Arbitrary Waveform Generator hacked to SDG2122X (120MHz)
SDS1104X-E – 100MHz oscilloscope hacked to SDS1204X-E (200MHz) w/options
SLA1016 – Logic Probe for SDG1x04X-E
SSA3021X+ – 2.1GHz spectrum analyzer hacked to SVA1032X (3.2GHz SA + VNA)

Siglent (like Rigol) sells gear that is easily hacked to add functionality including bumping a lower-end model up to a higher model in the same line. This is smart marketing: it lets them get higher prices from larger companies that won’t hack while still providing very attractive price points to hobby and small business users who couldn’t otherwise afford the higher models, but are willing to hack the lower models.

For the most part, I’m quite pleased. The Siglent gear always seems to meet or exceed its specifications and the specs are quite decent. There is a huge community supporting them in places like eevblog with in depth reviews of SDS1104X-E, step-by-step guides to hacking the SDS1104X-E as well as usage, repair, and enhancement tips.

I buy much of my new test gear from Saelig and TEquipment, both of which have provided excellent service and I recommend. If you’re thinking about buying new bench gear, you might give Siglent a look!

Nordic Power Profiler Kit II (PPK2)

Posted on October 13, 2023 by David Albert

I do a lot of IoT development involving battery-powered wireless devices. These devices must have very low average power consumption to facilitate long battery life. They typically spend most of their time in a low-power sleep mode, drawing a few uA or even nA and then wake periodically to take measurements, operate controls, and transmit and receive messages. Transmitting can draw hundreds of mA.

So the dynamic range of current draw can span 5 orders of magnitude! Moreover active periods are often very brief (sometimes just tens of uS). Measuring that sort of highly dynamic power consumption with fast transient events is a big challenge.

Current is generally measured by measuring the voltage drop across a shunt resistor. Unfortunately, a shunt resistor large enough to allow measuring a few uA will introduce unacceptable voltage drop if trying to pass 500mA. So measurement devices must have many shunts and measurement circuits and be able to switch them in/out of line very rapidly while sampling the voltage drops across the shunts very fast.

My go-to device for this sort of dynamic power analysis is the Joulescope which is simply phenomenal. It has 1.5nA-1mA resolution (depending on the measurement range), samples at 2MS/s (250kHz BW) and switches shunts as fast as 1us. The software is excellent too. The only problem is: it’s expensive (around $1K), so it’s not something I can put on every bench or easily design into test fixtures.

Hence my latest tool: the Nordic Power Profiler Kit II (PPK2) which is sort of a poor-man’s Joulescope. It has many of the Joulescope’s features, but all are spec’d significantly worse. It’s also 1/10 the price. It also has one feature that the Joulescope lacks and is quite useful. The PPK2 is a credit-card sized device, powered by one or two micro-USB cables (depends on how much current you need…in my case, one is usually enough). It samples much slower (100Ks/s max) and is limited to 5V; resolution varies from 100nA to 1mA depending on the shunt range, it doesn’t measure voltage at all (so you can’t use it to observe voltage drop), and the software is significantly less mature. It looks like a bare board, but the components are actually covered/protected by a clear acrylic shield so it’s bench/desk safe.

On the plus side it has a built in programmable power supply that can output 0v8 to 5v0 (drawn from the USB supply). That by itself is an incredibly handy feature. With the Joulescope, I need it and a bench power supply to power the DUT. The ability to power a 3v5 DUT *and* monitor its dynamic power behavior while only tying up one USB port and the bench space needed for a credit-card-sized device is super-cool. It also has 8 digital inputs you can use as a poor-man’s logic analyzer to correlate digital events (e.g. turn on transmitter) with power consumption. The Joulescope has such inputs too.

So far, I like it. The measurements match my Joulescope nicely – except for very fast transient events where the Joulescope shines and the PPK2 suffers. The built-in programmable supply is awesome. The software needs some work. Most critically, the data logger needs a continuous mode where it fills the RAM buffer and then wraps; the software currently fills the buffer and then stops, requiring a manual restart to keep monitoring current consumption and resetting all counters. This is particularly bad when what you want to do is measure average power consumption over a long period (e.g. a day or a week). At 100Ks/s, the RAM buffer fills very quickly so you can’t monitor the DUT at high speed for more than 500s. At 1Ks/s you can monitor for 13h, but fast events will be missed or improperly measured which defeats the purpose of such devices. What’s needed is a continuous mode that wraps when the RAM buffer is full but keeps accumulating average, max, and total power used. (Nordic are you listening?)

Overall, I’m pleased with the PPK2 so far and expect to buy more for use on benches and in test fixtures. If you can’t afford a Joulescope (or just want a super-compact USB-powered variable supply), the PPK2 seems like a great choice.

Siglent SDG2042X hack

Posted on September 3, 2023 by David Albert

Update 2025-Nov: I liked the SDG2042X so much I bought another used unit and hacked it to 120MHz as well…both units are great and I use the frequency counter extensively. Something worth noting about these that I had not realized before is that they have a fairly good time-base; much better than the SDG1000 series. It is advertised variously as 1ppm or 2ppm, so clearly a TCXO; I tested the new unit against a DOXCO and it was better than 1ppm, showing only 0.7ppm time-base error.

I purchased a used Siglent SDG2042X which is a 40MHz arbitrary waveform generator with bonus 200MHz frequency counter to replace my aging 25MHz arbitrary waveform generators. Test gear from Chinese manufacturers like Siglent and Rigol has steadily improved over the years and is now quite competitive. Despite my appreciation for the amazing quality of old HP/Agilent gear, in many cases, it makes more sense to buy something new from Siglent.

This generator works well and is feature-rich, but I was curious about an easy hack mentioned on eevblog (see The Siglent SDG2042X Thread the hack that worked for me used the SCPI commands (telnet to port 5024) and python keygen; see here: https://www.eevblog.com/forum/testgear/siglent-sdg2042x-hack-door-closed/msg5731469/#msg5731469) that describes how to upgrade it to 120MHz which turns it into the top of the SDG2K line: SDG2122X.

It turns out that the hack does indeed work and is easy to do; see results below. I don’t know if manufacturers intentionally leave these hacks available to make them attractive to hobby users while still selling the higher priced models to businesses who would be less prone to hack them, but either way, it’s much appreciated (and is a very nice signal generator)…thanks Siglent!

Note that the scope in the pic below is also easy to hack to 500MHz at 5Gs/s and moderately easy to hack to enable all optional functions.

The bonus frequency counter works quite nicely too, providing details like min/avg/max, sdev, duty, and frequency deviation in ppm relative to a reference frequency you specify. It needs about -10dBm (200mV) of signal at 200MHz, but lower levels at lower frequencies (e.g. it works at -20dBm ~= 63mV at 35MHz). Because the SDG2042X can be slaved to an external 10MHz standard, the generated frequencies and counter measurements can be very accurate; I usually keep it and other gear slaved to an external DOCXO standard.

SDG1025 Firmware Update

Posted on May 27, 2023 by David Albert

I upgraded my SDG1025 to the latest firmware (1.01.01.39R7) from Siglent (available here). It seems to have fixed an annoying issue: the need to select the language each time it started.

Of note: the update process is straightforward, but initially I tried it using a freshly formatted 32GB USB flash drive and although it recognized the drive, it did not see the .ads file on it. I tried it with a very old (128MB) flash drive and it saw all the files on that drive and the update process went smoothly.

If Siglent ever releases new firmware for the SDG1025, I hope they will consider moving the very useful frequency counter feature selection to the top menu level (which has room for another choice on the soft keys). Right now, it takes 4 button presses to get to it which is excessive.

STLink V3-PWR

Posted on April 8, 2023 by David Albert

Update 2023-July: I no longer recommend using this until ST software support improves. At present, there are simply too many issues and it is a frustrating experience. The software seems somewhere between alpha and beta quality: the software that does work has major issues and many important software applications (including from ST) don’t work with it at all (including openocd which works fine with other STLink V3s).

I do a lot of design and development work using STM32 microcontrollers. The low-cost STLinkV2 hardware debug tool is part of what has made these processors so successful: the ability to quickly, inexpensively, and easily flash and debug firmware is a big deal. ST has gone a long way to make life easy for developers and we love them for it!

I have boxes of STLink V2s and clones; I use them all the time. Recently, I’ve started migrating to the STLink V3 and this post covers their most expensive variant: the STLINK V3-PWR which integrates some interesting features including:

SWD debug tool (flashing, debugging target)
USB-to-serial converter
variable power source for target (1v6 to 3v6 in 100mV steps)
dynamic current monitoring (100nA to 500mA) with 100ksps (50kHz BW)

It has additional hardware capabilities (SPI, I2C, GPIO, JTAG) that I haven’t tried yet (and it’s not clear that software support for them is ready).

Key Strengths

The STLink v3 is fast for flash/debug – even faster than the V2 (which was plenty fast)
The integrated serial interface works perfectly and saves another plug
Nice injection molded enclosure
The variable power source lets me test devices at voltages other than 3v3 and 5v which is more useful than it sounds…it’s often important to understand how the DUT will operate at 1v8.
The ability to monitor dynamic power consumption during development is incredibly useful. I didn’t fully understand this until I started using a Joulescope and realized how much added visibility it provided. I now routinely develop with the DUT powered through a Joulescope so I can better “see” what’s happening. The V3-PWR dynamically switches between 4 current ranges to provide a huge dynamic measurement range without imposing excessive burden voltage.

Cost:

$95 is crazy expensive for an STLink and serial dongle (V2 clones and serial dongles are individually available for as little as $2 from AliExpress in nice compact aluminum shells).
$95 is crazy cheap for a dynamic power monitor that covers a wide enough current range for IoT development is hard to come by for even a fraction of the price. The Joulescope, is roughly 10x the price (but much more powerful).
If ST make the design public as they did with the V2, we can expect to see the price decline dramatically once Chinese clones appear.

Hardware Limitations:

100ksps (50kHz claimed BW) sounds great, but in reality, that sample rate doesn’t provide enough resolution to understand the dynamic power consumption of many IoT devices. It’s super-common for battery-powered devices to wake briefly (uSeconds), do something, and go back to sleep. This is one of the major differences with the Joulescope (2Msps, 300kHz BW).
No pass-through current/power monitoring. Batteries have higher impedance than most line-powered supplies and that impedance varies with temperature and other dynamic feactors (e.g. passivation). The V3-PWR lets you observe the consumption of the DUT, but not its dynamic interaction with a battery. (another difference with the Joulescope).
Power to the DUT is via ~3.5mm screw terminals…not banana jacks, not pluggable screw terminals, not even lever terminals…this was the wrong place to save a few cents.
Connection to the computer *requires* USB-C or the rare USB-A port that supports both data and charging. Maybe this isn’t a big deal or even a limitation, but it’s worth being aware of.

That Dang STC14 connector

The biggest DOH! with the entire STLinkV3 series is ST’s adoption of a 50-mil “STDC14″ connector. 0.050” (1.27mm) connectors are simply awful, particularly for developers. Many targets won’t have the same STDC14 connector and now you can’t use the ubiquitous 100-mil dupont jumpers as we did with STLinkV2. Instead, you need a breakout board to adapt the 0.050 pins to 0.100. You can get inexpensive STDC14 breakout boards from OSHPark (9 PCBs for $11.10 shipped) and mount either these nice but very expensive and somewhat fragile Samtec connectors (left) or these much cheaper and more rugged CNC Tech connectors (right).

Software Limitations

No cumulative or average power measurement. This is a huge deal for battery-powered devices (and one that ST can and should add to their software). Understanding average power consumption is key for most battery-powered IoT devices. The sampling limitation might limit accuracy, but this is an easy-to-implement and important missing feature.
The UI is limited (something ST will also hopefully improve over time). It provides a graphical display of current measurement (see below), but is missing features we’ve come to expect from scope-type equipment such as: horizontal or vertical cursors to make and document precise measurements, automatic axis scaling, adjusting the time-base dynamically, etc. ST software developers would be smart to license Joulescope software for the V3-PWR.

When the software associated with the V3-PWR matures, it will get a thumbs up from me. If/when cheaper clones start appearing, I’ll probably have a box of these to replace my STLink V2s. If ST provides an API, these could also form a very useful building block in many factory test fixtures.

Competitors

Nordic Power Profiler Kit 2 (PPK2) – similar price, wider voltage/current ranges, can measure external current sources (i.e. battery), but no debug/serial functions and no enclosure.
NXP MCU Link Pro – half the cost, but you must select one of two current measurement ranges using a jumper and neither of those ranges fully cover my measurement needs. Within the selected range, the MCULink dynamically switches between 2 sub-ranges, allowing good dynamic range, but not on the level of the other devices. It also has more limited power supply capabilities (two fixed voltages: 1v8, 3v3) and has no enclosure.

Disk Abuse

I left the monitor running overnight at a high sample rate with acquisition time set to infinite. It turns out that this writes a ton of data to the disk and by morning it had chewed through 160GB of disk space! Even worse, it’s not obvious where the disk space went! So for other users who find this issue, the power acquisition log files are in Users/myUserName/AppData/Local/Temp/Power_Monitor/Acquisition.

ST could significantly improve the software application (STM32CubeMonitor-Power) by adding a few features, some of which seem quite easy:

Checkbox to En/Disable logging (off by default) so you can watch power consumption as you develop/test.
Link to the acquisition logs folder so users can find it easily
Stop/play button so you can pause acquisition to measure an event and then resume
Cumulative power usage counter (so you can confirm expected average power consumption over a long test)
Cursors (current and time) so you can measure and document events
Auto-scale of the Y-axis should adjust to mA when appropriate. A scale from 0..500000uA is just silly and it’s surprisingly annoying to try to distinguish 15000 from 150000.

TinySA Ultra

Posted on June 2, 2021 by David Albert

I have been waiting for a long time for a usable low-cost spectrum analyzer and it looks like that wait is over

Update Jan 2023: I sold the original TinySA and upgraded to a TinySA Ultra. It is more expensive (about $140), but much more capable. The Ultra provides an extended frequency range up to 6GHz (level-calibrated to 5.3GHz) and adds several nice features including a remarkably functional bonus signal generator (cw, am, fm) and a 4″ LCD screen (welcome eye-relief for folks with high-mileage). This is not a toy; it has its limitations, but the specs now make it quite usable (PN=-92dBc/Hz, 2dB absolute amplitude accuracy, 1ppm frequency standard, 200Hz min RBW). So you can observe signals with reasonable accuracy and good resolution.

As before, I bought from R&L Electronics (the authorized US outlet – be careful to avoid poor-performing clones). I’ll do some testing with it soon, but you can see a few quick tests below.

Some resources:

Tiny SA Wiki
YouTube channel (with lots of good usage info)

The front-end is better but still easily over-driven (and damaged above +10dBm) so I usually use it with a 20dB fixed attenuator in line. As an example of how it compares to higher-end gear, here’s a 915MHz signal FM modulated at 5kHz shown (frozen) on the TinySA Ultra and on a Siglent SVA1015X. Peak measurements are within 1.5dB and 100Hz. Not bad!

I was recently looking for RF interference in the WiFi band and ran the tinySA Ultra and a (much more expensive) Anritsu BTSMaster for a bit with both in max hold mode to get a feel for what was out there and I was pleased with the results.The pictures won’t match precisely due to the nature of sweep times and max hold, but the results were quite good and immediately showed the strong channel 1 signal with fairly good accuracy on both frequency and amplitude. I’m quite fond of this little SA.

There is also a TinySA app in development; it lets you connect to the TinySA from your Windows PC and capture traces; it’s a little rough at present and the sweep rate gets very slow when you are capturing to PC at low spans (in part because the default is 1k points), however it’s still nice to be able to capture traces directly. Here’s an example of a 433MHz signal FM modulated at 1.5kHz

OLDER VERSION (note: below is about the older TinySA, not the Ultra)

I bought a TinySA spectrum analyzer for $55 from R&L Electronics (one of the official dealers). If you get one, try to use the official sites; there are lots of bad clones out there. The TinySA is, as the name implies, a tiny, battery-powered, touch-screen, 100kHz – 960MHz spectrum analyzer. I have been very pleasantly surprised by its performance.

It has its limitations, but it is the first usable low-cost SA I’ve found for looking at sub-GHz FM signals. There are plenty of low-cost toys out there (see my earlier post regarding the “Simple Spectrum Analyzer”) that claim to do spectrum analysis, but they have always had fatal flaws (inaccurate or horribly coarse resolution bandwidth). This one has quite good frequency and amplitude accuracy out of the box and a usable 3kHz RBW.

It has some limitations too (But for goodness sakes, we’re talking about a pocket-sized spectrum analyzer for $55!!!):

960MHz max frequency
3kHz resolution bandwidth (RBW)
Amplitude uncertainty seems to be around 2dB
Easily over-driven (claims +10dBm max input, but works much better below -10dBm)

Below are some pictures showing the SA in action, including both strengths and limitations.

For comparison, here is what the signal generator output looks like on a higher-end piece of test gear (Anritsu MS8609A):

I do a lot of work in the 902-928MHz ISM band which is often impacted by strong nearby cellular signals. I looked at the 50MHz span around 915MHz using both a TinySA and an Anritsu CellMaster. The TinySA did an outstanding job, showing the same results but with much greater dynamic range (the Anritsu is meant as a cell tower service tool and supports looking at much stronger signals). On both analyzers, you can see a strong LTE signal at 892.5MHz. Measurements were using a Linx sleeved dipole centered at 915MHz.

Atmel ICE

Posted on October 15, 2020 by David Albert

I used an Atmel ATTiny13A in a project; it only has 8 pins and all are in use. There isn’t much memory (program or data), so debugging can be a challenge…but fortunately, there’s Atmel-ICE to the rescue! The Atmel-ICE (see product page) is inexpensive and can be used to program and debug Atmel SAM (ARM) and AVR targets. To get real value out of it, you need to use it with Atmel Studio: their free IDE built on Visual Studio.

Connector weirdness:
The ICE connects to your PC with a micro-USB cable and to your target with a ribbon

cable (ATATMEL-ICE-CABLE). The cable has both a 10-pin 50-mil JTAG connector and a 6-pin 100-mil SPI ICSP/DW connector configured for the standard AVR ICSP pinout. The red wire on the cable denotes JTAG pin 1; when connecting to an AVR ICSP header the red wire connects to pin 3 (SCK). Strangely, the pin 1 indicator on the 6-pin plug does not denote pin 1 but actually connects to pin 5 (nReset). Anyway, you can trust that the 6-pin connector is correctly wired for the ICSP header (SPI/DW) even though the markings suggest otherwise. Assuming your ICSP header has pin 1 (MISO) in the top left, then the key bump on the plug and the red wire will be on the left side. For examples, see this picture showing the connection to an Uno or this closeup showing the connection to a Mega.

Unlike most of the ICSP programmers, the ICE does not supply power to the target; the power pin (2) is just used to detect the target voltage. The green LED near the edge ICE enclosure indicates target power. This is unfortunate as it makes it much less useful as a programmer, but it allows it to work with both 3v3 and 5V targets. (I would have preferred if they had added a target voltage switch and a 3v3 regulator)

You can use the ICE in two connection modes: ICSP (SPI) for flashing the target only or serial debugWIRE (which is where the really neat stuff happens). DebugWIRE is Atmel’s one-wire in-circuit debugging solution using only the reset pin! In this mode, you can connect to your target, set breakpoints, examine variables (sort of), step through code, and do real source-level debugging while still using all of the pins on your target. Kudos to Atmel…this is really slick…and it works! (Note: you have to set the debugWIRE enable fuse on the target – Atmel Studio will prompt you to do this). Don’t forget to clear that fuse when you’re done debugging!

Atmel studio works well; you add your files into the Solution Explorer, build, and start debugging! The only really annoying thing is that the debugger doesn’t let you examine variables that have been optimized away by the compiler (and you usually need to build with the code optimized because there is so little code space)…so if you want to examine variables, you need to make them global.

Some good references:

http://www.crash-bang.com/debug-atmel-ice/
https://wspublishing.net/avr-c/arduino-uno-atmel-ice-connection/
https://wspublishing.net/avr-c/arduino-mega-atmel-ice-connection/