The DAQCplate (Data Acquisition and Controller) from Pi-Plates adds a rich set of input/output options to your Raspberry Pi. It includes seven powerful digital outputs for driving external devices such as relays and high-current LEDs, as well as eight analog-to-digital inputs for measuring temperature, voltage, humidity and more. Additionally, there are eight digital inputs, two analog outputs and seven general-purpose indicator LEDs.
Pi-Plates are a family of stackable and interchangeable add-on circuit boards that allow you to interact with the outside world using your Raspberry Pi. Every Pi-Plate is designed to provide a robust set of features at minimal cost while using the fewest pins possible on the RPi header. Pi-Plates are mechanically and electrically compatible with all revisions of the Raspberry Pi with 40 pin headers (including the Pi 3 Model B and Pi Zero) and are designed to satisfy the needs of hobbyists, experimenters and professionals.
Whether it's for assembling a kit, hacking an enclosure, or creating your own parts; the DIY skill is all about knowing how to use tools and the techniques associated with them.
Skill Level: Noob - Basic assembly is required. You may need to provide your own basic tools like a screwdriver, hammer or scissors. Power tools or custom parts are not required. Instructions will be included and easy to follow. Sewing may be required, but only with included patterns.
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If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.
Skill Level: Competent - The toolchain for programming is a bit more complex and will examples may not be explicitly provided for you. You will be required to have a fundamental knowledge of programming and be required to provide your own code. You may need to modify existing libraries or code to work with your specific hardware. Sensor and hardware interfaces will be SPI or I2C.
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If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.
Skill Level: Rookie - You may be required to know a bit more about the component, such as orientation, or how to hook it up, in addition to power requirements. You will need to understand polarized components.
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I was able to get the DAQC plate up and running quickly and immediately deployed it to interface an old HP Spectrum Analyzer from the 70s - Interfaced +20V/0V digital I/O easily (resistors) to the IO bus and was able to successfully tune and read the center frequency as well as sweep the RF and read the resultant response for display on a Raspberry Pi.
The only critique of the DAQC plate is regarding the resolution of the ADC - the coarse positioning via the 8-bit DAC was workable, but the 8 bit ADC was insufficient to achieve the desired results - I ended up interfacing an outboard 12 bit ADC to read back the frequency and Amplitude information.
It strikes me that the incremental cost difference between an 8 bit ADC (or DAC) and a 12 bit ADC (or DAC) is fairly small and the improved Analog range capability of the DAQC plate would be significantly improved, thus providing a significant boost to the overall usefulness of the board at a small increment of selling price (maybe on the order of $5.00)
The ADC's on the DAQCplate are actually not 8-bit - they're 10 bit ADC's.
I had it set up and running a camera battery load test on two batteries within minutes, using a Pi 3 and python.
I bought this a few months ago as part of a larger project, so I just got to it and tested it. I tested analog and digital inputs as well as the interrupt function and they all seem to work. Build quality seems good. The documentation is not what I had hoped, however. I see no orderly, detailed description of the Python library. I would want to see more examples and sample code with a lot of comments. I would also like a more detailed hardware spec. For example, I could not find out the minuum voltage level required by the digital inputs to trigger a true condition. This was important as I have to reduce a 12 V signal via a voltage divider.
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How could we condition the digital analog inputs for 4-20mA? , industrial sensors work under these parameters. your comments please
Hi there, it sounds like you are looking for technical assistance. Please use the link in the banner above, to get started with posting a topic in our forums. Our technical support team will do their best to assist you.
Please feel free to reach out to PiPlates, the manufacturer. That being said, your scenario might be outside of the scope of either their and/or our technical support team.
What is the ADC sampling frequency? The documentation does not immediately describe this feature in detail.
Pi-Plates communicate to the Raspberry Pi via the SPI interface. This limits the effective A/D sampling rate to about 1000 samples per second. The 50Khz bandwidth mentioned in another comment here is the maximum allowed input frequency.
User guide says 50KHz limit.
The user guide says the bandwidth is 50 kHz.
Sampling rate is defined as the number of samples acquired in one second. The Nyquist theorem states that a signal must be sampled at least twice as fast as the bandwidth of the signal to accurately reconstruct the waveform.
Given a max bandwidth of 50kHz, the sampling rate would have to be a minimum of 100 ksps.
Hate to be pedantic, but Nyquist says that you sample at double the waveform frequency to be able to accurately measure the frequency of the signal. To accurately reconstruct the waveform, and measure more nuances than frequency, you must sample at a much higher rate than that. How much higher depends on your desired fidelity.