With the default hardware and hardware there are four current ranges +/- 1, 10, 100 and 1000 uA. So +/-1000uA is the maximum allowed current range. It is possible to change this but it requires a hardware modification and firmware modification. You won't be able to set higher than 1000uA without these changes. You would need to make these modifications yourself. There are some forum notes on increasing the current range here http://forum.iorodeo.com/topic/67/increasing-current-ranges-to-detect-ma The firmware modifications can be enabled by uncommenting the the #define CURRENT_VARIANT_MILL_AMP and commenting the #define CURRENT_VARIANT_MICRO_AMP in the ps_hardware_variant_defs.h file https://github.com/iorodeo/potentiostat/blob/master/firmware/libraries/potentiostat/ps_hardware_variant_defs.h You then need to reflash the firmware.
Posts made by Will Dickson
RE: How to set curr_range to more than 1000uA?
RE: How to run different experiments on different channels using Multichannel Potentiostat
It is not possible to run multiple experiments, such as constant and cyclic voltammetry, simultaneously with the multiplexed version of the Rodeostat. You can use up to 7 working electrodes, but you still only have 1 reference and 1 counter electrode. So the time course of the potential between the all of the working electrodes and the reference electrode will be the same during a test.
RE: How to run SquareWave tests with Multichannel Potentiostat
This is not currently possible with the current firmware to do the SquareWave test with the multiplexer. Enabling this will require some fairly extensive modifications to the device firmware.
RE: troubleshooting new colorimeter
You might try testing to see if the there is an issue with either the LED or the sensor board.
First test the LED. Open up slider on top of the colorimeter and ensure that the sensor is exposed to light - ambient room light should be fine. Make sure there is light hitting the sensor. With the top open and light hitting the sensor start the colorimeter-basic program and try running the "Calibrate" routine. You should see the LED flash red, green, blue ,white in sequence. Note, you can increase the duration which each LED color is on by increasing the number of samples - say from 500 to 5000. If the LEDs are flashing all four colors in sequence then they are working.
Next check to see if the sensor board is working. Again to do this again you will want to expose the colorimeter sensor to ambient light. In this case it might be easier to unscrew the top of the colorimeter and pull out the sensor board. It should be connected to the Arduino by the gray ribbon cable. It doesn't need to connected to the LED by the 4-connector cable for this test. Expose the sensor to room light and run "Calibrate" in the colorimete-basic program. Then partially obstruct the light hitting the sensor with your hand or a piece of paper and run the "Measure" routine. As less light is hitting the sensor you should see nonzero absorbance values for all color channels.
RE: Measuring CV currents around +- 10nA
I think the +/-1uA is probably pushing it. I think you would probably want something more like a +/-50 or 100nA range. It is possible to modify the Rodeostat to reduce the current range. We have made modified versions with +/-60nA and +/-100nA ragnes. There are some notes on how to do this in the "hardware/pcbs/teensy_shield/notes" sub-directory of the project repository https://bitbucket.org/iorodeo/potentiostat See the file named "nano_amp_mods.txt". We made two versions the 2nd worked best. The changes were as follows:
R5 = 6.04 MOhm, C19 = 10nF capacitor (100nF range)
Digikey PN: 541-6.04MCCT-ND, and 311-1136-1-ND
R6 = 10 MOhm, C20 = 100nF (60nF range)
Digikey PN: 541-10MAZCT-ND and Digikey 311-1361-1-ND
There is modified firmware available for these ranges you just need to enable the CURRENT_VARIANT_NANO_AMP #define in the in ps_hardware_variant_defs.h and comment out the CURRENT_VARIANT_MICRO_AMP #define. The ps_hardware_variant_defs.h is found in the firmware/libraries/potentiostat/ sub-directory.
RE: OpenSource software recommendation?
I think darktable would be a reasonable option https://www.darktable.org/
You can find a list of supported cameras here https://www.darktable.org/resources/camera-support/
There is some information of camera tethering here https://www.darktable.org/usermanual/en/tethering_chapter.html
RE: Problems with serialport AppImage on Linux (Rasperry Pi 3)
The current AppImage binary is built for x86-64 whereas the rpi is ARM. So in order to get this to work you will need to rebuild the serialport-bridge AppImage from source for ARM. This can be done on the raspberry pi itself. The source code for the serialport-bridge can be found here https://bitbucket.org/iorodeo/serialport-bridge You should be able to rebuild the package using "npm build". I have tried this, but I think it should work.
I've been working on firmware examples for the new featherwing. Right now all of the examples use circuitpython. I haven't put in an online repository yet. I will do this in over the next few days. I've been pretty pleased with how well circuitpython has worked for this - very easy and quick to program.
Right now all of the firmware examples just stream the data back to the host PC over USB. I am also pretty excited about trying to make some standalone devices which use feathers such as the pygamer https://www.adafruit.com/product/4242 which have a display, battery connection/charging, SD card, etc. The rodeostat featherwing can be plugged directly into the connector on back. It seems super nice for making a battery powered portable device. The pybadge is also interesting https://www.adafruit.com/product/4200. I think both are still available from Digikey.
We should have the featherwing PCBs available in about two or three weeks. There is some uncertainty on when we will receive the PCBs ... not surprisingly.
Yes with the Rodeostat the best way to add BLE is by using one of the expansion headers. This will require some custom modifications to the firmware.
Also, we will have another option available soon. We been working on a featherwing format potentiostat called the Rodeostat Featherwing. You can find some images and the design files here https://bitbucket.org/iorodeo/rodeostat_featherwing/ .
The Rodeostat Featherwing is a really stripped down version of the Rodeostat Potentionstat with a single voltage range from -1.65V to 1.65V and a single current range. We will make several current range variants such as +/-1, 10, 100, and 1000 uA.
You should be able to use the Rodeostat Featherwing with any development board which is compatible with the Adafruit feather Specification https://learn.adafruit.com/adafruit-feather/feather-specification . There are tons of different feather development boards available https://www.adafruit.com/feather and several have BLE built in such as this https://www.adafruit.com/product/4516 and this https://www.adafruit.com/product/3406. So this would be an easy way to make an embedded device with both BLE and a potentiostat.
RE: Installing the Multiplexer Expansion Board
Yes, you can connect the +/-15V on the rodeostat to the +/-12V on the multiplexer.
Earlier revisions of the Rodeostat used a +/-15V DC-DC converter to provide the power rails for the op amps on the Rodeostat. Whereas, more recent revisions us a +/-12V DC-DC converter. The multiplexer is labeled to match the more recent versions of the Rodeostat. However, the multiplexer will operate fine on +/-15V.