@Will-Dickson Thank you so much for the suggestions. I could make it work with the AVRISPMKII programmer. Also, your modified firmware, especially the makefile was very helpful and made my work absolutely easy. Thank you once again.
After buffering the data, the limitation in sampling frequency appears to come from the testTimer function. This function has a specific runtime, and runs on a timer interrupt. If the timer interrupt's period (testTimerPeriod in ps_constants.cpp) is smaller than the actual time it takes for the function to run, the function does not run correctly, yielding incorrect and strange results.
For those looking to increase their sampling frequency, this seems to be the next bottleneck after the data streaming. Perhaps some alteration/optimization of this function could increase the sampling rate slightly, perhaps not.
Ultimately, to increase the sampling frequency of the Rodeostat, you can:
Decrease MinimumSamplingPeriod within ps_constants.cpp in order to remove the software limitation on sampling frequency
Remove calls to convertMstoUs in ps_periodic test and in ps_system_state.cpp, allowing for periods to be passed directly in units of us, rather than being limited to a sampling period of an integer in ms
In serviceDataBuffer (in ps_system_state.cpp) , modify the function so that it does not transmit data until test done flag has been set (by putting an if statement around most of the function).
With this we were able to achieve higher than the stock sampling frequency for a small number of periods (this was limited by the memory, since the data buffer would get filled with too many points since we did not clear it until the end). Unfortunately, high frequencies like 10kHz or 100kHz did not seem to be reachable.
In addition, thank you @Will-Dickson for your help figuring this out.
Yes, the XL transilluminator does fit inside the imaging enclosure. It is a snug fit, but it works. Unlike the Small, Midi and Large transilluminator, you do have to take the door off in order to take the transilluminator in/out of the enclosure. But if you are planning on keeping it in there most of the time this shouldn't be an issue I would think.
There is an adapter we ship with the XL version, which is not a frame but a base plate for the transilluminator to sit on.
I have added the Extra Large XL option to the product page now, so you should be able to select it.
We are currently out of Cheapstat stock and at this time we don't have plans to restock in the forseeable future. However, if you want to make one yourself, we do still have the bare Cheapstat PCB for sale here. We have also just updated the Cheapstat documentation to include the bill of materials for this board. Let me know if you have any questions about this.
Going forward we will be focusing most of our efforts on the Rodeostat open source potentiostat. If you are interested in using the Rodeostat or have any questions, please let us know and we will be happy to help.
We are currently out of Cheapstat stock and at this time we don't have plans to restock in the forseeable future. However, if you want to make one yourself, we do still have the bare Cheapstat PCB for sale here. We are working on updating the Cheapstat documentation to include the bill of materials for this board, so that should be on the site very soon. Let me know if you have any questions about this.
Going forward we will be focusing most of our efforts on the Rodeostat open source potentiostat. If you are interested in using the Rodeostat or have any questions, please let us know and we will be happy to help !
@Jo Awwww bummer, I wish you could attend too. Well, thanks for pushing it out further. Maybe there's someone who's an avid user of IO Rodeo's stuff that may be interested? I think you guys represent an important community that GOSHers don't know well enough. Just at thought.
Unfortunately, we don't have a version colorimeter software which works on Chrome OS.
We do have software for linux. so you could install ubuntu on the Chromebook using crouton https://github.com/dnschneid/crouton This will allow you to run ubuntu while preserving your original Chrome OS system.
First, the output voltages are set at discrete time points via the testTimer which run by default at 5kHz. To make a reasonable approximation of a sine wave you will probably want enough points - maybe 50 or so. So you could probably output reasonable approximations of sinusoids voltages up to frequencies of about 100Hz.
Second, the data is not sent back to the PC (or other device connected via UART) at every update of the testTimer. Rather it is sent at a lower sub-sampled rate set by the sample rate (or actually sample period in the firmware). The maximum value for the sample frequency is 1000Hz. You will need sufficient number of sample points at which to measure the current you get in response to the sine wave output. So maybe 20 or 30 or 50 ... the exact number depends on your needs. Lets say that 20 is sufficient. Then this further reduces the maximum sinusoid frequency to 50Hz (1000/20).
Third you will need to take into account the bandwidth of the current measurement range you are using e.g. +/- 1uA, +/-10uA, +/-100uA, +/-1000uA. Each of these channels will lowpass filter the measure signal to some extent based on the resistor capacitor combination used in the feedback network of the transimpedance amplifier. The more sensitive channels will have lower cutoff frequencies. The +/-1000uA and +/-100uA channels have pretty high cut off frequencies such that it won't be an issue. However, the +/-10 uA and +/- 1uA ranges have cutoff frequencies of approximately 47Hz and 4.7Hz respectively. So if you are using these channels this will limit the bandwidth of your measurements somewhat or at least you should be aware of the possible attenuation of the measurements at higher frequencies.
That is a good question ! We haven't tried using glass instead of acrylic for our transilluminator. However, you could certainly put your gel onto a small glass plate over the clear acrylic when you are cutting gels to protect the acrylic. You can look for small glass plates online e.g. McMaster-Carr and other stores. We will also have a look at finding some glass plates to recommend with our different transilluminator sizes.
If you would like a replacement for your scratched clear acrylic surface, we can send you one, no problem, just let us know and we will happily help with that !