How to troubleshoot an SDI-12 adapter

January 11, 2025 Leave a comment

If your SDI-12 adapter isn’t “working”, don’t panic! The adapter has been tested with an actual SDI-12 sensor so it’s supposed to work. Go through the following steps to troubleshoot the adapter. As a matter of fact, DO the following step BEFORE you put any adapter to use for the first time!

1. Remove any sensors or external power connections from the adapter. Check for any physical damages on the USB port, the board, and terminals.

2. Plug the adapter into a windows computer, if the computer recognizes the adapter with a “USB plugged in” chime, and your device manager shows a serial port just appeared, proceed. Otherwise, the adapter is either damaged or the USB port may be damaged. If it shows a message saying an unrecognized device, the USB chip is damaged. The following is a screen shot of my device manager. The serial port COM15 wasn’t there before I plugged in my adapter. Opening the property of the port shows the manufacturer as FTDI (the USB chip). This confirms this step is successful.

3. While connected to PC, use putty (available in windows app store) or tera term and connect to the serial port you observe that appeared in step 2, with 9600 baud rate and 8 bit data, 1 bit start, 1 bit stop, no parity (default settings for many terminal programs), type in zI!, which is zee-EYE-! without hitting enter. If the adapter responds, then proceed. The following screen shot is the set up screen of PuTTY. Make sure you select the connection type as Serial and type in the correct serial port name and speed.

You won’t be able to see what you typed in (no local echo unless you turn on that feature) but you will see the response from the adapter as below. Your version of firmware may be different from 1.5.9 (159) though. If there is no response, the SDI-12 interface chip may have been damaged.

4. Close PuTTY connection. Disconnect the adapter from your computer. Connect a sensor that you know works (just tested to work). Reconnect the adapter to your computer and open PuTTY again. In the terminal program, issue ?! command. If the sensor responds with its address such as 1 in the following screen shot, the adapter works. You can follow up with an identification command 1I! that is 1-EYE-! and replace 1 with the address you see on screen after ?!. You may have to connect 12V to the adapter’s power input and select to use this power input with a jumper for certain sensors. Consult with your sensor’s manual for operating voltage. If there is no response from either ?! or the identification command, the SDI-12 chip may have a damaged data pin.

Before asking for some help, please test the adapter with the above procedure and tell me what you see. Try to avoid generic descriptions such as “failed” or “not working” and describe what you did and what you observe.

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July update

July 7, 2024 Leave a comment

Nearly everything I have been selling is low in stock or out of stock by the end of May, when I was pretty busy with projects so I decided to take some time off and build back up my stock. So now I have most of the adapters back in stock and will be building more of them this summer. So if you were looking to get some adapters but found out that it was out of stock, they should be in stock now and most are ready to ship.

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FloraPulse stem water potential sensor supported

March 2, 2024 Leave a comment

updated20slide20image

After some tests by Dr. Michael Santiago and myself, I can confirm that the FloraPulse stem water potential sensor is supported. One just needs a 1-second delay between SDI-12 commands. Here is a forum post:

https://liudresllc.com/community/supported-sensors/florapulse-stem-water-potential-sensors/#post-5

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Read analog voltages, digital ON/OFF, and pulse counts on SDI-12 adapters

February 15, 2024 Leave a comment

If you have read about my SDI-12 USB adapters, you might know that besides connecting SDI-12 sensors to a USB port for PC/raspberry pi, the adapter has an option to read basic 0-5V analog voltages, digital inputs, and count pulses. This extra feature comes as a 12-pole terminal block at the top of the adapter, allowing up to 4 analog inputs, or 4 digital inputs, or 4 pulse counters:

This option has been around for a number of years but has not been widely used. Most people purchase the basic adapter without this $10 option. So is this option useful for you? That depends on what you are planning to do. Say for instance, you have an analog sensor such as a temperature and relative humidity sensor that you want to read besides SDI-12 sensors, if 5mV to 10mV accuracy is good enough for you, then you can read your analog sensor with this option. Do you have a pulse sensor such as a tipping-spoon rain gauge or a flow meter? Then the pulse counter feature would help you integrate these sensors with ease. If you have digital ON/OFF or HIGH/LOW sensors that have 0-5V or 0-3.3V logic, you can read them too.

The easiest way to acquire these sensors is to get the ADI (analog digital input) feature with your purchase. For extra $10, you will have an adapter that comes with a 12-pole terminal with all 4 inputs tested. The best part is, reading these sensors is very easy, just like reading an SDI-12 sensor. This way you can treat an analog temperature sensor just the same way as an SDI-12 sensor. Here is an introductory video:

Here is a link to my online store. To select the option, drop down the selection menu and choose “Analog and digital input header”.

https://liudr.square.site/product/sdi-12-microusb-adapter/50?cs=true&cst=custom

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SDI-12 miniUART module – perfect for prototyping and embedded projects

February 1, 2024 2 Comments

Mini in hand

After some requests from customers, I have decided to design a small module that can help everyone prototyping and embedding SDI-12 in their own designs. Enter, mini (rewind! I should have posted this piece last year but forgot it was still in draft mode!)!

This mini module measures only 1″ by 1″ (2.54mm*2.54mm) and is a quarter the size of the regular adapter:

mini vs regular

The immediate advantage is you can easily place it on a breadboard for prototyping like this, with an ESP32 dev board:

mini with ESP32 dev board on breadboard

The size of the mini is designed so that there is one hole on the breadboard for each connection. Some dimensions in mm. Notice there are two mounting holes in case you wish to mount this on your circuit board securely:

mini dimensions

The relative locations of the 6-pin ICSP header, the bottom-right mounting hole, and the top right SDI-12 bus hole are unchanged from the regular board so I can still flash firmware on this board using my existing programmer!

Here is how I connected the module to my ESP32:

breadboard for mini

So I first put my ESP32 on the breadboard, with 5V connected to to top red and gnd to top blue. I also connected 3.3V to bottom red (not used) and gnd to bottom blue.

Then I connected 21 to 5V and 25 to gnd, both to top power strips. I also placed a 0.1″ jumper between 21e and 22e, another one between 24e and 25e. This is to make 22 5V and 24 GND, to match the module, and also keep the 22a-24a available to connect a TRS adapter to connect to an SDI-12 sensor.

Also, I connected 22j to gnd on bottom, and 23j (orange wire) to module TX3 which connects to my ESP32 serial port 1 RX, and 24j (yellow wire) to module RX which connects to my ESP32 serial port 1 TX.

mini with ESP32 dev board hooked up

Notice that because of the 0.1″ jumpers, my 22a is 5V and 24a is GND. The original pin on the module for this pin is NC or not connected, so you can jump GND to it with no issues. That also leaves 23a as SDI-12 signal. I then placed a TRS adapter in pins 22a-24a, with tip connecting to 22a (5V), ring connecting to 23a (SDI-12 signal), and 24a to GND:

mini with ESP32 dev board trs adapter and sensor

You can’t really see which pins I connected to ESP32 because my ESP32 dev board doesn’t have silk screen on top. I was using pin 13 for serial port 1 TX and pin 34 for serial port 1 RX. You can use what fits you.

If you want to use a raspberry pi pico instead of an ESP32, here is how I wired them together.

Here is a screen recording on my computer. You can see how I was reading from the mini module and SDI-12 sensors. It’s very similar with both pico and ESP32 dev boards because I am using micropython on them both.

Here is a link to my online store:

https://liudr.square.site/product/sdi-12-uart-mini-module/73?cs=true&cst=custom

This is the dedicated page for the module including instructions and more updates:

SDI-12 miniUART module

Dimensions:

miniUART module vs regular USB adapter

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Soldering practice kit

June 10, 2023 Leave a comment

Since many users of my adapters are learning IoT, arduino, raspberry pi, etc. I thought that I could help them learn some basic electronics skills such as soldering. Plus, I have many printed circuit boards that I no longer use. You only need one such board and some male header pins to learn how to solder anyway and you don’t really have random boards just lying around for practice. So here it is, a $2.49 investment in soldering practice:

1. One printed circuit board with many 0.1″ spacing holes

1. One row of 40-oin male break-away headers

1. One small cut sheet of blu-tack putty to hold parts to be soldered (I used a blob in the video but I’ll supply fresh ones cut from a sheet)

Here is a play list of how to solder on a printed circuit board:

The kit is now for sale on my square store:

https://liudr.square.site/product/soldering-practice-kit/74?cs=true&cst=custom

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Forum is online!

June 6, 2023 Leave a comment

After much consideration, I have invested in a wordpress-powered business website and started an online forum. To visit the forum, just click the “FORUM” tab or this address:

Forum

You can ask questions and read announcements from the forum. I’ll try to double-post on both forum/announce and blog. I hope the forum will serve both potential and existing users of my adapters so we can share questions/solutions.

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Video tutorials on raspberry pi + SDI-12 USB adapter

June 6, 2023 Leave a comment

It’s been a while since I have time to record more videos. So here’s a series of new videos on how to run the python code on a raspberry pi to log data from your SDI-12 sensors, from step 1 assuming a beginner’s skill level. I know that a raspberry pi 4B is hard to get or justify the high prices but you can use any raspberry pi for data logging, such as 3B or 3A, or 0 or 0W. So the point of logging data with a raspberry pi isn’t lost in the face of rpi 4B shortage. Read on if you want to know my trick to get yourself a latest raspberry pi to tinker with or play with your kids.

Here are the videos, in their own playlist:

These videos have been also added to my growing original playlist:

So if you really want your hands on a new raspberry pi so you can start tinkering in the summer but hate the high price, here is a “hack” to get one at a reasonable price. Here is straight from raspberrypi.com, the offerings:

You notice that there is a raspberry pi 400 computer kit? That is a keyboard-form factor raspberry pi 4B with 4GB RAM for 70USD! An equivalent raspberry pi 4B with 4G RAM is priced at 55USD but has been out of stock for 2 years! So grab yourself a raspberry pi 400 instead! You can learn raspberry pi right away! Now that most places selling this kit will sell you a 100USD kit that includes:

  • A power supply
  • A mouse
  • A microHDMI-to-HDMI cable
  • A 16GB microSD card loaded with the raspberry pi OS (may be 2yr old)
  • A printed book of the 4th edition of the beginner’s guide (highly recommend over the .PDF file)

In my opinion, especially if you are starting off with raspberry pi, or have a kid or two at home not knowing what to do with their summer time, grab the 100USD education kit! You may need to help them from time to time because some of the coding content could be hard but it’s a good brain exercise for adults as well! I’ve been doing this with my kid for a week or so and it’s been a blast, drawing snow flakes and regular and regular star polygons etc. using Python turtle from the book. I think I might have a chance to get my kid through Python this summer, finally!

So if you absolutely don’t want the above listed items (have too many of those already?) and just want the bare keyboard computer, go to digikey and get the 70USD module:

https://www.digikey.com/en/products/detail/raspberry-pi/SC0373/13282408

Make sure you get the US keyboard or whatever your native language keyboard is so you aren’t surprised by the extra symbols šŸ˜€

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Eureka Manta +35 water sensor tested

September 3, 2022 Leave a comment

One of the users of my adapters informed me that they have successfully tested the adapter with this sensor. This is a water sensor that does a lot: “turbidity, temperature, pH, conductivity, and dissolved oxygen sensors, with the option to add ORP and depth sensors” and quite a bit more, according to the manufacturer’s webpage:

https://www.waterprobes.com/product-page/trimeter/product-page/manta-35

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Q/A UART version adapters

August 10, 2022 Leave a comment

Q: I plan to integrate your adapters to my own controller, not a PC or raspberry pi USB port. Does your UART version adapter have all necessary resistors and no USB chip to interfere with the UART port? How do you make connection between the UART adapter and my own controller?

A: Yes, all necessary resistors are in place for the UART version of the adapter and the USB chip is not on the chip to interfere.
Here are some of the points:

  1. The adapter has a 6-pin header that is soldered underneath the adapter to avoid making jumper wires from being vertical, which takes extra space, or from going over the optional A/D header.
  2. The adapter requires 5V and GND to be supplied to it since it doesn’t have the 5V and GND from the USB connector. SDI-12 has 5V logic levels so the 5V supply.
  3. The 6-pin header has GND, TX_3V (back of board), 5V, RX, TX_5V, RST from left to right. This is where you power the adapter and connect to its serial port. RST is reset. Unless you want the option to reset the adapter, you can leave it disconnected. Reset is 5V logic.
  4. If your controller is 3.3V logic (ESP32, raspberry pi serial pins, rp2040 etc), connect your controller TX to adapter RX, then your controller RX to adapter TX_3V.
  5. If your controller is 5V logic (Arduino UNO, MEGA2560 etc), connect your controller TX to adapter RX, then your controller RX to adapter TX_5V.

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