peter64

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About peter64

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  1. Hello, I was hoping to use your uC32 board to control 4 stepper motor drivers and to provide debug information over serial back to a PC. Unfortunately though the UART routine implemented in HardwareSerial only has a buffered RX implementation and not a buffered TX implementation. This means that at lower baud rates or with larger debug payloads the time to send the data into the serial line can take a rather long time. I looked around online and I can't find any pre-built libraries that implement an IRQ based UART TX Buffer on the PIC32 that would be compatible with the framework supplied by chipkit. I found one but it's based on entirely different compiler and set of libraries so doesn't appear compatible. http://phoenix-mindgame.blogspot.com/2014/09/pic32-uart-transmission-using-tx.html The regular core arduino HardwareSerial library was updated at some point to support a TX buffer, would diligent consider updating the HardwareSerial implementation that comes with chipkit for the uC32 to also support a TX buffer? UPDATE: I managed to implement a TX buffer without too much difficulty, not sure how robust it is though, this fixed my issue by eliminating blocking serial writes. This might be a useful feature improvement you would consider for the future.
  2. Hey Attila, Sorry to ask a slightly unrelated question (I can create a new forum post for it if you want) but is it possible to increase the Scope record view to more than 10 million samples when operating at 1-2 Mhz? I was considering geting an analog discovery and using it to record 1-2 minutes of 1-2 Mhz sample data. (this is currently what I'm doing with my arduino). The demo AD2 in Waveforms appears to have a limit of 10 million samples in record mode in Scope view though. Base on my understanding record mode is just buffering data through the 2x8K scope buffer directly to usb (so I'm guessing the 10 million sample limit is imposed purely by the Waveforms package). Is there anyway to override or change this max value ? Or would I need to directly interface with the waveforms SDK to run in a continous record mode for 1-2 minutes? Thanks for any help you can provide.
  3. Hey Attila, Thanks so much for the detailed and comprehensive reply! It hadn't even occurred to me that the -IN was connected to the -OUT (which I was tying to ground through the USB) I'm going to give it some more thought, but you've provided me with a number of options. I think either an analog discovery or usb2 isolator will be in order. Also I didn't realize the digital discovery measured the vio current that is really cool. Unfortunately 0.6mA is not enough resolution in this case as I'm measuring around 4-20 uA.
  4. After searching the forums a little more about ground loops I came upon the following post. I'm wondering if something like the following would solve my issue and if it would be compatible. Perhaps it would even allow one to use a digital discovery and analogy discovery on the same pc connected to the same circuit? Any thoughts? https://hifimediy.com/high-speed-usb-isolator-480Mbps
  5. Hey clf, I just had another try and I think I found the issue. The arduino I was using to monitor the uCurrent gold outputs was wired to the same PC via USB. This appears to have caused some kind of ground loop where current would flow through one us device and out the other (I suspect it's related to the battery in the uCurrent gold but if you have a better explanation I would love to know the exact reason this happened). The uCurrentGold Current input was wired in series with the VIO from the diligent to the sensor a MPU9250. The arduino was wired up with A0 going to uCurrent Gold Voltage Out + and GND going to uCurrent Gold Voltage Out -. Then it was connected to the same PC via a regular USB cable. The solution was to get two notebook pc's fully disconnect them from ground (and each other, network cables, kvm, etc). Then I could monitor the uCurrent gold output with my arduino whilst still using the digilent to control the sensors. The other alterative was to connect my battery powered multimeter to the uCurrent gold (but I wanted to use the arduino to collect the high frequency current usage waveforms). I was considering buying a real usb oscilliscope (or perhaps the analog discovery) but I don't know if the ADC inputs of the analogue discovery will suffer from the same issue. Infact I don't know if I can run the analog discovery and digital discovery on the same pc at the same time (I expect not). Anyways I have a solution for the time being (thanks for your offer of help, it encouraged me to have another try and find the issue). Peter
  6. Hey attila, It' didn't make a difference if I connect it to VIO before or after I enable. I did get it to measure a current by putting it in the ground path instead of vio. Unfortunately the value that was measured was totally incorrect (1.8 A or there abouts). When I connect my regular multi-meter in series it gives accurate current measurements. I'm just curious why I can't connect the uCurrent Gold in series without either triggering over current protection or getting current readings that are totally wrong. Any ideas you might have would be appreciated. I'm not sure if this is a high capacitive load or not, below is a link to the schematic. http://www.eevblog.com/files/uCurrentRev5schematic.pdf Thanks, Peter
  7. Hello, I recently purchased a digital discovery and I was hoping to use it to test various sensors. It works fine for sending requests to sensors and making simple scripts. However I can't seem to use it to measure current flowing from the VIO pin to the sensor in conjunction with the uCurrent Gold I own. http://www.eevblog.com/product/ucurrentgold/ Every time I attempt to do it it triggers over-current protection. Could you explain why this happens and if there is any way I could use my uCurrent Gold with the Digital Discovery to accurately measure current flowing from VIO to the sensor? I expect there may be no way to do what I want to do, so just understanding why it isn't possible would be satisfying. Thanks, Peter