Have you tried cal signal of your scope?
Can you give us picture of that cal signal?
In the digital realm and oscilloscope's "bandwidth" has very little relation to the frequency of the signal you're looking at.
eg. Imagine you have a single rising edge on screen - that's a 0Hz signal.
On a 100MHz 'scope the trace will rise in half the time that it takes on a 50Mhz 'scope and that's a big difference.
If you're doing digital work and basing a purchasing decision on that rather than bandwidth and number of channels then you're doing it wrong.
Me? I say 4 channels/100Mhz/Serial decoders is a minimum requirement for digital/microcontroller work.
I really don't care what brand you buy, but: Make a shortlist based on that specification then compare prices. Now consider if moving the trace up and down a bit faster is worth that much money.
Fixed it... Turns out it wasn't anything with the scope... or firmware.
I also changed the power extension cord (it's a power splitter as well). I guess it wasn't making good connection and/or some hell of a noise was picked up from somewhere...
In the digital realm and oscilloscope's "bandwidth" has very little relation to the frequency of the signal you're looking at.
eg. Imagine you have a single rising edge on screen - that's a 0Hz signal.
On a 100MHz 'scope the trace will rise in half the time that it takes on a 50Mhz 'scope and that's a big difference.
We're only talking about 2x speed improvement so 5 nSec vs 2.5 nSec? All of the timing specs I've worked with (in embedded software) are in units of uSecs. And I do not design nor implement my software to have tolerances in the tenths of nSecs. So an extra 2.5 nSecs buys me nothing. I can see that you probably would want the best speed possible if you're designing a microcontroller system from scratch. But if you're in that situation, you'd probably want something much higher than 100 MHz. For me (and probably most hobbyist) whom will most likely only use the scope to troubleshoot serial buses, GPIO controlled devices, then the difference between a 50 MHz and a 100 MHz is minimal.
In the digital realm and oscilloscope's "bandwidth" has very little relation to the frequency of the signal you're looking at.
eg. Imagine you have a single rising edge on screen - that's a 0Hz signal.
On a 100MHz 'scope the trace will rise in half the time that it takes on a 50Mhz 'scope and that's a big difference.
We're only talking about 2x speed improvement so 5 nSec vs 2.5 nSec? All of the timing specs I've worked with (in embedded software) are in units of uSecs. And I do not design nor implement my software to have tolerances in the tenths of nSecs. So an extra 2.5 nSecs buys me nothing. I can see that you probably would want the best speed possible if you're designing a microcontroller system from scratch. But if you're in that situation, you'd probably want something much higher than 100 MHz. For me (and probably most hobbyist) whom will most likely only use the scope to troubleshoot serial buses, GPIO controlled devices, then the difference between a 50 MHz and a 100 MHz is minimal.If you're doing digital work and basing a purchasing decision on that rather than bandwidth and number of channels then you're doing it wrong.
Me? I say 4 channels/100Mhz/Serial decoders is a minimum requirement for digital/microcontroller work.
I really don't care what brand you buy, but: Make a shortlist based on that specification then compare prices. Now consider if moving the trace up and down a bit faster is worth that much money.
Do a search for "Rigol 1054z problem" on youtube and watch NatureAndTech's video and see if you'd want to live with that kind of lag. I don't feel serial decoder is a must have because after all, all serial protocols are asychronous so once you capture one transaction waveform manually and examined and debugged it to make it work, then all subsequent transactions will work. What's the point of having a decoder to tell me what my data is? It's nice to have, but not really needed at lease at the software development role. Plus having a serial decoder won't remove the requirement of manually inspecting the transaction waveforms especially if you're doing bit banging.
My list looks like this
1. 4 channels
2. 50 MHz minimum. 100 MHz ideal.
3. Deep capture memory depth (none of that Tek 12.5K point crap)
4. Robust.
Spoken like a true softie
100MHz was barely adequate for digital logic in the 1970s, and speeds have increased a little since then. Even jellybean logic parts have setup and hold times of ~1ns and propagation times of ~2ns.
You should realize that a 50 MHz square wave running into a 50 MHz scope will display as a sine wave. There is just not enough bandwidth to allow the 3rd, 5th, 7th ... harmonics. Even a 25 MHz square wave will look odd because there isn't enough room for the odd harmonics.
The point is, you may or may not be able to see exactly what a signal looks like or where it is switching. This gets particularly important with clocked protocols like SPI.
I like the SPI decoding on the 1054Z. I know it is only decoding what is on the screen but with a 1 MHz clock, I can get 12 bytes across the screen with perfect decoding. No, I can't decode the Library of Congress from the buffer. I have printf() for that kind of nonsense. Once I have a set of functions that correctly transfers data, I will probably not be using the scope on those signals again. But I need to see the setup time on CS', I need to understand the relationship between MOSI & MISO edges versus CLK. In fact, I want to use the cursor to measure the setup and hold times just to be certain I am in spec. Partly because 1 MHz is terribly slow and I'll eventually want to kick it up to 10 MHz or higher.
I bought my 1054 SPECIFICALLY for the 4 channels. I actually gave up bandwidth over my Tektronix 485 which can do 350 MHz. Four channel decoding of SPI is EXACTLY why I bought the thing. I am working with the W5500 TCP/IP chip and everything is transferred over SPI. Faster is better than slower...
* I have other Irks - like the slow saving of screenshots to USB memory (I love to annotate debugging or problem resolution sessions, and screenshot a lot - and that drives me nuts sometimes).
Were I to use it for work - depending on the type of work - of course - it may not be up to the job. But as a home lab having the extra features at an affordable price makes sense.
Spoken like a true softie
100MHz was barely adequate for digital logic in the 1970s, and speeds have increased a little since then. Even jellybean logic parts have setup and hold times of ~1ns and propagation times of ~2ns.
Precisely my point. If you're gonna do hardware design, you probably want something better than 100 MHz. What I'll mostly do is to interface say something like a Raspberry PI, Arduino, Beagle Board or what not to external peripherals like ADCs, DACs, cameras, LCDs, LEDs, etc.. I won't be designing my own Raspberry PI nor any of the external peripherals. So we're talking about serial bus and GPIO debugging mostly. Max SPI speed is 4 MHz, UART you'll be mostly be under 1 MHz, hack even DVD video is only like 9 Mbps. So a 50 MHz is fully capable of debugging all these things over a serial bus.
Don't get me wrong, I'd delighted to get a 100 MHz scope, but if I have to choose between a slugish/buggy 100 MHz and a fluid/robust 50 MHz, I think I will choose the 50 MHz.
I don't remember when was the last time I had to look at anything higher than 4 MHz.
Just write the code to work at 10 Mhz, then when you're ready, just cut all the setup time and clock by 8 and you've got 80 MHz.
I don't remember when was the last time I had to look at anything higher than 4 MHz.
Equating signal bitrate to oscilloscope bandwidth after reading the last couple of pages tells us something.Just write the code to work at 10 Mhz, then when you're ready, just cut all the setup time and clock by 8 and you've got 80 MHz.
Also: Believing that digital signals aren't affected by the pieces of wire they have to travel down...they just arrive, right? If the code is correct, that's all that matters.
Also: Believing that digital signals aren't affected by the pieces of wire they have to travel down...they just arrive, right? If the code is correct, that's all that matters.
You could use a "microprocessor brake" to slowdown your system during debugging phase.
Similar as what was possible with the "Amiga Bremse" from Rex Datentechnik to slow down the Motorola 68000 microprocessor in the Commodore Amiga 500 computer
http://www.bigbookofamigahardware.com/bboah/product.aspx?id=1704
I actually have this product, but have never found the time up to now to test it on my Amiga 500
Depends on what you are debugging. If you are paying attention to software maybe you don't need to look into signal integrity unless you see something really odd.
If you wish to continue to snip and ignore points about signal integrity, then that's your choice.
Quoting a digital signal speed in MHz "Max SPI speed is 4 MHz" is revealing, and indicative.
There is a lot of difference between something capable of basic visualisation of UART/SPI/GPIO levels (a 10MHz scope would suffice), and a 50/100NHz scope.
If you wish to continue to snip and ignore points about signal integrity, then that's your choice.
Quoting a digital signal speed in MHz "Max SPI speed is 4 MHz" is revealing, and indicative.
There is a lot of difference between something capable of basic visualisation of UART/SPI/GPIO levels (a 10MHz scope would suffice), and a 50/100NHz scope.
I will mostly use off the shelf modules, ie Arduinio and its shields etc, so signal integrity should not be an issue. But even a 50 MHz scope is capable of troubleshooting "signal integrity" for a 10 MHz signal no? I don't know how a 100 Mhz one is much better than a 50 MHz one. Slightly better, but you'll still leave wanting more.
Ok. So you have all convince me, maybe I spend more $ to get a 100 or even a 200 MHz one.
I will mostly use off the shelf modules, ie Arduinio and its shields etc, so signal integrity should not be an issue. But even a 50 MHz scope is capable of troubleshooting "signal integrity" for a 10 MHz signal no?
I don't know how a 100 Mhz one is much better than a 50 MHz one.
I think you have already agreed with my statement that the serial decoder not much of use when you said "In fact, I want to use the cursor to measure the setup and hold times just to be certain I am in spec.". If you have to measure the waveform with the cursor, then why do you still need to use the decoder? I have worked with quite a few people over the years and with one exception one time when some guy brought in an expensive logic analyzer with build in SPI decoder and we played with it a little like a toy, I have not see a single person use any serial decoder ever.
Two words: "Square edges".
Square waves, single rising edges, anything with a square corner is made up of an infinite series of frequency components.
A 10Mhz square wave shown on a 50Mhz scope will only have the first and second harmonics intact, the third will be attenuated by 3dB and the fourth harmonic will be almost gone.
Only two-and-a-bit harmonics is a serious distortion of the input signal. Not square at all. A 50Mhz 'scope simply cannot display a 10MHz square wave properly even with perfect, inductance-free wires and connections (which don't exist).
On a 100Mhz 'scope you'll have the third, fourth and fifth harmonics intact, plus some of the sixth. That's not a small difference from a 50MHz 'scope, it's huge.
PS: And in reality a hacked DS1054Z has about 130MHz bandwidth (measured) so you'll have all of the sixth harmonic and a lot of the seventh. And that's why we like them, slightly sluggish vertical movement notwithstanding. $400 for that much bandwidth and four channels is something that can't be ignored.
As I said earlier: Find that performance from other manufacturers and compare the price. If slightly faster controls is worth that much to you, go ahead...
We don't put up with the DS1054Z's idiosyncrasies because we're ignorant, unrefined clods who don't appreciate the finer things in life like you do. We put up with them because we can have a decent 'scope plus a whole lot of other toys besides - $600-$800 buys a lot of other stuff.
According to Agilent the rule of thumb is f(bw) = 5 * f(clk) to get the 5th harmonic.
Nope. 5 * f(clk) is only the second harmonic.
f(clk) is the base frequency
3*f(clk) is the first harmonic
5*f(clk) is the second harmonic
7*f(clk) is the third harmonic
etc.