Thanks mate, good to also hear appreciation for a bit slower pace. It feels sometimes like you should talk as fast as possible on KZfaq.

Hi, apologies for the long wait. The potentiometer was connected to the Pi. It's possible to connect to an external source, but the ground of that source must be connected to the MCP3208, or the ground of the Pi and that source must be connected.

Yeah that's exactly how you'd do it, you need to call ReadChannel3208() for each measurement you want to make. Good luck!

I'm honestly not sure what could be causing the fluctuations. It could be the use of long wires or somewhat dodgy connections. The readings might also be more stable if you use higher resistances, so the current that's running is lower. For good readings a stable power supply is also important. As for your multimeter, I think that won't work. You're assuming a 5V reference, but I suspect you don't actually know what the real voltage on the Pi's 5V rail is. You need a reliable multimeter to establish that after all. It will have quite some deviation to begin with, many power supplies for Pis actually supply 5.1V or 5.25V to compensate for wire losses for example. If the actual reference is higher than the assumed 5V, then the real voltages shown by a multimeter will also be higher than what the chip/code say. Finally keep in mind the MCP3208 is not an accurate chip per se. Yes it has 4096 counts of resolution, but a few counts worth of noise is normal. Besides that is also has a few counts worth of offset error and gain error. I don't know the details of that entirely, I never tried squeezing this level of accuracy from an MCP chip. I usually just need tenths of volts at most. If your cheap multimeter is a modern chinese one, then it should be accurate. EEVBLog reviewed/tested many of them against callibrated standards, they were always very accurate.

To read resistances you essentially need to create a resistor divider. In this way you can convert an ohm value to a voltage, which can then be read with an ADC. Finding the math for voltage dividers online should be quite simple.

Got it! Been a few years forgot how functions worked, passing parameters to a defined function when calling the function, etc. pretty cool. Great video

I'm afraid I can't, that's not something I've tried to do. I can find some videos about doing that with Arduino, but I don't know how easily those translate to Raspberry Pi

Good to hear, thanks for watching

That's a good idea, but there's also a compromise there. A low-pass filter also reduces the response time of the system.

Isn't a capacitor to ground a low pass filter? Still pretty noisey... ​@@antalz

Yeah they're 100 nanofarads. That's a somewhat high value for ceramics. Voltage limit has to be higher than the voltage that you're trying to filter, I believe I used 30V or 50V capacitors. Too high voltage limit doesn't matter. You use ceramics because they have a good high-frequency response, they're small, they're cheap, and they do the job. Electrolytics for example have much higher capacity generally, but are also bulkier, more expensive, and sensitive to polarity. You should really have a set of ceramic capacitors on hand, you can get 1000 for under 20 bucks. They're like resistors in that sense, just have them on hand because they're so often used and so cheap.

@@antalz Thank you so much for a detailed response!! Subbed

@@antalz I've just bought one of those capacitor kits from Amazon, and it has x40 100mF capacitors. I wanted to ask, under what circumstances would you use a lower mF capacitor? I understand getting one with a voltage rating that is higher than needed, but I wondered if there are times when a specific uF/mF capacitor is required. Thank you again for your detailed replies!

@@djtyros Did you get an electrolytic set or a ceramic set? A 100 milli-Farad is huge, a 100 micro-Farad is quite normal for an electrolytic but huge for a ceramic, I believe. The markings on ceramic capacitors should tell you their capacity in picofarads.

@@djtyros Broadly speaking, if you want to make a voltage stable then you use relatively large values, which you sometimes see in typical L7805 circuits. Usually something like a 100uf electrolytic with a 100nf ceramic. The exact values don't matter so much, you just want the big capacitor for the bigger spikes, and the ceramic for small high-frequency stuff. If you use a 220nf or a 46nf capacitor instead that's usually totally fine. In other cases like filters and integrators and whatnot the exact value of a capacitor can matter a lot, and those cases are unfortunately outside my expertise.

That depends on how occupied they are. MOSI/MISO/SCK can be connected to a range of different devices, and then each device needs its own chip select wire connected. Then you can speak to any device by setting its chip select high. If the screen physically blocks you from connecting MOSI/MISO/SCK, or if the screen requires all the bandwidth, then my advice would be to get an Arduino, and connect it to the Pi via USB. Then on the Arduino put a simple sketch that reads its analog inputs, and send that data over to the Pi via the USB serial. You'll need to decide what format to use so send/receive the data, and a small bit of code on both devices to make it happen.

@@antalz thx for the response

@@antalz I have put all together, but i get this error: spi.open(0,0) IOError: Errno 2 No such file or directory I have spi enabled like you did in your video

I also changed the code in AnalogInput-RPi-GPIO.py to use the 3008 (swaped the funktions). I dont know much about python and linux and all what i found online did not helped (sry for my english)

@@Snoweuph Did you enable SPI in the raspberry pi config? I'm not sure I covered it in the video, but that is required and that's what usually leads to that error.

Hard to say. I don't know what the lowest reference voltage is these will accept, and even then there will be some read noise. I would say the lowest is about 10 counts, so 10*reference voltage / 2^bits

Yes! You wire each MCP3008 to MISO, MOSI and CLK, and then you must give each MCP3008 its own chip select pin. You can then control which MCP3008 you want to talk to by which pin you pull low before starting the read. That's pi.write(CS_ADC, False). It might actually make more sense to put that line into the read function itself. You can also control any other kind of SPI device alongside the MCP3008. The only trouble is you often need to look into the datasheets and mess with bitwise logic, unless a standard library is already available to use.

It's pretty complicated. You take the second byte of the adc array (the first byte is adc[0]), you do a logic-and with 15, which is 00001111, and the result you bitshift 8 steps to the right. The reason for bitshifting 8 to the right is because right after that you add the bits that are on the third byte, the + adc[2] statement. The whole bitshifting stuff isn't too complicated, but it takes a while to wrap your head around. Unless you're specifically interested in writing your own SPI code to interface with other SPI devices, I would ignore this part. If you do want to interface with other devices it will take you a while to wrap your head around, and you need to study their datasheets carefully. You will also need an oscilloscope or logic analyzer to have any real hope of making it work.

For reading all the channels, just call ReadChannel3208(0), followed by ReadChannel3208(1), then 2,3,4 etc. Using a for loop or a list comprehension is probably a good idea.

I think the link in the description to raspberrypi-spy.co.uk has what you need.

You can write to a file like any other Python variable, there are dozens of tutorials on how to write to files.

@@antalz will it be stored in the sd card? Because I have send those data to a mobile via bluetooth ....I mean is real time data transmission possible With that?

@@shuchismitabagchi801 Yes it will if you select a file location on the SD card. I don't know how you can transmit over Bluetooth I'm afraid. You can use sockets to send over WiFi too, but you'll need to learn about serialising data and sockets for that to work.

@@antalz okk ,Thanks a lot

Unfortunately I'm not familiar with Picos

@@antalz any reference?

​@@creativearts4917 It appears the Pi Pico has SPI, so maybe you can use the existing libraries in python? Or are you using C? Whatever the case you will need to use the right pinout: datasheets.raspberrypi.com/pico/Pico-R3-A4-Pinout.pdf This might be helpful: www.digikey.be/en/maker/projects/raspberry-pi-pico-rp2040-spi-example-with-micropython-and-cc/9706ea0cf3784ee98e35ff49188ee045 If need be you can adapt the code from this video. Essentially you need to send 3 bytes to tell the chip you want data, and what channel you want it from, and then you listen to and decode the response. How to do that is in the code, but it involved bit-level stuff which is used very rarely, so it's quite a poorly covered subject.

10 bits for the MCP3008, and 12 bits for the MCP3208. Resolution is 3.3V/1024 or 3.3V/4096, respectively.