Products > Test Equipment
Sniffing the Rigol's internal I2C bus
EE-digger:
My thought could be out in left field but who knows ...
During production test, hardware could be "marked" as to its bandwidth and rise time capabilities. During final production configuration, units can be configured for the highest level product they can meet, or a lower level if sales demands more lower level units.
I've never been in a production environment where the required performance was not designed in but perhaps in higher volumes, and in China, final designation occurs sort of the way pistons, pins and connecting arms were mated in the earlier days of automobile production, prior to the discovery of design for mass production.
Just my $0.02
Den
EE-digger:
Here are some bandwidth and risetime numbers I measured on an MSO1104Z that I received two days ago.
There is a twist in bandwidth measurement that I noticed and may be of help to others. I apologize if this exists elsewhere.
While measuring bandwidth with an Agilent source (50 ohm output) and precision in-line termination at the scope, I found bandwidth to be much higher that expected (i.e. 3dB point around 190MHz or more). Too good to be true :)
On a Tek TDS784D (1GHz) with the same external termination, I noticed that the source appears to peak as you go above 120MHz. I knew the generator was flat (into a proper load) so repeated with the internal 50 ohm Tek setting. This I know to have very good return loss.
The source, as I expected, was flat. It turns out that with the 50 ohm external termination, with either the expensive Tek scope or the Rigol, you end up with peaking, probably caused by the scope input impedance (cap + inductance).
So, the numbers shown here were measured with the amplitude verified first into an internal 50 ohm scope.
Bandwidth: (all without any aliasing effects)
-3dB : 155 MHz
-6dB : 280 MHz
-9dB : 380 Mhz
Risetime: (measured with avalanche pulse source, 180ps rise time)
Rigol reports : 1.2ns
correcting for the avalanche pulse rise time : 1.18ns
In addition to the beautiful graphic presentation of the Rigol scopes (for any money as far as i can see, having handled recent vintage Tek, LeCroy and Agilent), what impresses me is that the Rigols do not "fall apart" until you are up around 4X the bandwidth (from aliasing and other DSP related issues).
But now, I can't wait until mods are available for this MSO.
The I2C and SPI, while not real time, appear to work fairly well but I only have 12 hours left :'( On I2C at least, you can take a sweep at a long horizontal time, the stop the scope and zoom in, whereupon you will get the decoded values as soon as a packet or packets are fully on screen, as observed by others. I2C was at 100kHz and SPI was at 500kHz.
Den
dewey:
To upgrade a DS4014 appears to involve putting a firmware update on a USB stick, booting from it and restarting. (instructions thread here)
I just ordered a DS4014, and would like to experiment with its bandwidth. However, I don't want to be the proud owner of a $2300 brick. From the above thread, it sounds as if perhaps the poster above me here is experiencing what might be a change in the DS2072A's ability to be upgraded, perhaps due to hardware level changes made by Rigol?
Does anyone know if Mr. Kreb's tool (here) will still work on a DS4014, as delivered today, November 2014? Has the firmware changed at all since the tool was written, or will that matter? Any reports of hardware changes made by Rigol?
I'd really appreciate anyone's input.
Thanks
-Dewey
H.O:
There's no longer any need to apply the modified firmware since seronday found/figured out the option codes for bandwidth selection on the DS4k. See reply #3607 in this thread. It's been verified to work with the latest firmware available today (00.02.02.01.01). You can use Riglol 1.03d
Bud:
--- Quote from: Sparky on November 11, 2014, 07:10:15 am ---1) The 300 MHz key is sometimes incorrect, and the DS/MSO detects and rejects it as such,
--- End quote ---
Just had a DS2072A updated to 300MHz. FW 00.03.00.SP1, HW 2.0
Used Bildschirmkopie to dump data from the scope via a SCPI command
:SYST:UTIL:READ? 15441920,13262848
then goes rigup-0.4 to generate the keys
then again Bildschirmkopie to install a key
:SYSTem:OPTion:INSTall A_KEY_WITHOUT_DASHES
Bildschirmkopie : http://peter.dreisiebner.at/rigol-bildschirmkopie-lan/download.htm
rigup-0.4: http://gotroot.ca/rigol/
I am not sure why bother changing the scope firmware via a USB stick risking to brick the device, unless it is because of other goodies that I am not aware of. If all you want is options and bandwidth, the above procedure is non-intrusive and safe.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version