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MCP3008 penzu entry

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I have a rpi4 and have successfully replicated the project listed here using the eTape sensor (etape tutorial) I am satisfied with the performance using long breadboard and T-cobbler. In order to make my setup more compact I purchased the pi-EZ connect board. When I connect all the jumper cables; the sensor no longer works and I get a 3.3V reading from the sensor which does’t make sense. It should be within 1.0-1.8V in order to convert into a sensible volume. The sensor does require 3.3V to run; and I’m just getting that value back? I double checked the jumper cables and even tried different cables; but I can’t get it to work. I re-assembled with the t-cobbler and breadboard and it works. Not sure if the pi-ez board is bad? The little circuit chip on the right in the photo is the MCP3008. Would like some suggestions or advice on what troubleshooting steps to take from here. Thanks.

rpi

 New contributor
  • Ah, let me see. I read the tutorial you mentioned and found it runs on Windows Visual Studio. So I guess you are running Win VS C# to test the eTape. Please correct me if I misunderstand your set up. Now I guess you are now porting the Win C# program to Rpi Mono C#. If my guess is correct, please give me the program listing and perhaps I can try debugging the section related to MCP3008. Another workaround is to forget Mono C# and borrow some python MCP3008 somewhere. – tlfong01 4 hours ago
  • (:) eTape Liquid Level Sensor on SPI MCP3008 (Rpi2 Win10 IoT Core) – Daniel Porrey, hackster.io 2015sep16 hackster.io/porrey/etape-f4b457 (:) 12″ eTape Liquid Level Sensor + extras – AdaFruit US$40 adafruit.com/product/464 (:) Porrey Mcp3008 Source Code github.com/porrey/IoT/tree/master/source/… (:) YouTube eTape Liquid Level Sensor on MCP3008 (Win Visual Studio) – 2015sep12 youtube.com/… – tlfong01 4 hours ago
  • hi tlfong01, thanks for reply. I am not using C#. I am using python with the adafruit library. Here is my github: github.com/sktrinh12/tip_novus/tree/master/eTape_sensor . It works fine when using a T-cobbler and the breadboard; but the leds don’t turn on and the voltage is not right when I hook up this ez-pi connect board – Spencer Trinh 3 hours ago
  • Thanks for the clarification. If you are using AdaFruit python library, then there should be no big deal. Most likely it is just a careless wiring mistake, or an intermittently poor contact problem. Perhaps I should check your github python library later. Cheers. PS – I remember I saw your breakout board a couple of times in other forums. It is easy for newbies to misinterpret the tracing and short or open pins. – tlfong01 3 hours ago
  • is there a good method to try to troubleshoot? How would i test if there is a short ? – Spencer Trinh 2 hours ago
  • Ah the standard method for both newbies, ninjas, and hobbyist/industrial/medical/military/NASA grade professionals is the following: (1) Get a multi-meter use the “connected/disconnected” option to test all point to point resistance: near zero resistance would sound a beep, otherwise LCD screen show our of range resistance. (2) Use big resistance option to check resistance value of physical/electrical “neighoubring” points, which should read big resistance, say over one mega ohm. Of course the two test points might have other circuits connected. So smaller resistance might be OK. / to cont, . – tlfong01 1 hour ago
  • (3) Might also be useful to test points witch should pull up to Vcc or ground (usually 4k7 to 10k). Now you need a schematic to check that out. Actually there are other tests. For example, for MCP3008, you might need to use SPI “loopback” tests (search this forum for spi loopback programs), .. Ah lunch time. See you later. – tlfong01 1 hour ago
  • (4) I forgot to add that to do open/short testing using a mult-meter, you MUST POWER OFF!!!. (5) You might also need to use mult-meter to do voltage check. This time you should use the DC voltage 10V DC or similar range, and see if the voltage level of “some” points are Vcc or Ground level. Power on this time of course. WARNING – No guarantee no nothing won’t meltdown or blow up, but then your dirt cheep US$5 multi-meter might also have a fuse to save its life! – tlfong01 1 hour ago
  • You python program using linear regression algorithm is a bit newbie scary. For troubleshooting, you may like to try a simple bare bone MCP3008 ADC python program for reference, such as this one: raspberrypi.stackexchange.com/questions/99550/…. – tlfong01 4 mins ago   Edit
  • In case you find the above answer “blurred”, because of too many down votes, you might try to read this “clear” version: penzu.com/p/e800ce64. – tlfong01 18 secs ago   Edit
.END

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