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 ..read more

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 planni ..read more

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 ..read more

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 ..read more

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 vid ..read more

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 ..read more

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: 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 o ..read more

Despite the ongoing chip shortage, I’ve secured a batch of processors for more adapters. At the moment I’ve also built enough stock to last for a little while. So currently I have about 50 qty adapters including a few with analog inputs. I have more boards and ICs but want to conserve my parts. From what I saw, there won’t be a relief of chip shortage until a year from now, i.e. May 2023. I’ve maintained the price of $49 (sometimes $45) for the last decade by absorbing the cost of parts etc. I might be able to continue to do so if I get some help with assembly, such as getting a pick-and-plac ..read more

So the new revision is finally out! The processor is so small it took me extra time to make sure it’s in the right spot. The pitch between the small processor’s pads is 0.45mm or 0.018 inches so I can’t miss by half of that, usually 1/4 of the pitch, thus 0.0044 inches of tolerance, so less than 5 mils. The following shows how small the processor is. Overall it is 4mm (0.16 inches) wide (see E). Another change is the protection diode. To deal with constant shortage of various parts, I’ve added a surface-mount diode of the same type near the top right terminal block, the little black box. Thi ..read more

The above is an order of 9 adapters. So if you have received your order of SDI-12 USB adapters in a stack of boards, hope you will make good use of the M3 standoffs! I’ve been shipping bulk quantities of the adapters lately due to an increase of quantities per order. I thought, the anti-static bags are cheap but are waste once the adapter has been received. So if I could pack the adapters better, I may be able to ship more adapters with a more compact box. Also the standoffs are nice to have for anyone who will mount the adapters in boxes. If there has been any problems with this bulk packagi ..read more