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Please visit my SDI-12 USB adapter page and click the Where to buy link if you would like to make a purchase. There any many ways to purchase and pay:

SDI-12 USB adapter

24 Responses to Buy

  1. Hello. With (20X4 Serial LCD keypad panel – Phi-panel). I can make a vt100 terminal. Some code written for it. I am interested in your products.


  2. Fabio says:

    Hello, i’m very interesting in Phi-2 shield 20X4 but i have a few dubt that ios the best choice for my progect. I would make a chronometer with many countdown and it must be precise at 1/100 of second. Your Phi-2 shield 20X4 use the DS1302 but i must have the DS3234. It’s possible to change the chip or the are other problem? Sorry i’m new in arduino world’s.
    Other dubt is: how many pin are free for use for over input/output?
    Is it possible to change the diplay and make a GLCD in future?
    How much cost the optional 24LC512 eeprom?
    Can i make my own chronometer programs run on my arduino and pass to phi2 only the diplay, menu, read and save parts?
    Many compliments for the work, i’m sorry for my bad english.

    • liudr says:


      Replacing the character LCD with GLCD will not be possible with the current shield. GLCD needs 13 arduino pins. Once you use a GLCD on an Arduino UNO, you don’t have many pins left for anything else (2 pins for program upload + 13 pins for GLCD so 15 pins used and 5 left for everything else).

      The DS3234 is on SPI bus, and DS1307 is on I2C bus so they can’t be swapped. You will need 4 pins to control this RTC, while you only need 2 for DS1307. Hope this helps.

    • liudr says:

      I just realized I only answered half of your questions:

      There are just a few free inputs/outputs left and they are documented on the documentation in a table.
      the 24LC512 is available at (it’s one of the biggest in the industry in US)
      Price is $2 but maybe there will be some expensive shipping charge for overseas delivery.

      I think if you want to run your own program and pass the display and menu etc to phi-2 shield, that is fine. If you really want to save pins (all shields use many pins), I suggest you get a serial LCD backpack (without the LCD) and connect to it via a software serial port (use 2 pins). Then it will report back to arduino what button is pressed and arduino can just Serial.print() info to the screen. Even phi_prompt library elements (text area, menu etc.) are embedded in the panel for easy use such as Serial.print(“Please select:\nItem 1\nItem 2\nItem 3\n~”), with a few more characters as special command will make the panel render a menu and it returns you which option the user selected, nice?—phi-panel/

      There is even a faceplate option for the serial backpack:
      serial backpack with face plate

  3. Igor says:

    Dr. Liu, I live in Croatia and I’m interested in backpack kit. Can I connect to this kit 16×2 and 20×4 LCD screen? Can you sell me just backpack kit? or pcb with programmed mcu?

  4. Moises says:

    Dr. Liu, we would like to purchase 100pcs can you offer us a better price? Please consider the shipping to Mexico. Regards

    • liudr says:

      Hi Moises,

      Thanks for your interest! I will email you so we can start a discussion on what hardware. Yes, I ship worldwide. When we are talking 100pcs, I will ship insured and with signature requirement so it will get to you safely.

  5. George says:

    Dr Liu, is an assembled version of Phi-2 available for sale with GPS module and EEPROM. I am not very good at soldering and would prefer to purchase an assembled unit. Also, I would need help with changing the code to only write GPS data to EEPROM when a button is pressed. Would this be covered by your Software Help – One Hour of Programming? Please reply to my email address.
    Thank you.

    • liudr says:


      Thanks for your message. I have one assembled Phi-2 shield with EEPROM and GPS connector and 20X4 display ready to ship. If you need a 16X2 display version, I will have to order the GPS connector and assemble it for you. The GPS module is this one, which is probably better if you purchased it yourself since I have only one and am currently using it.

      Here is the connector I put on the shield:

      If you want the assembled 20X4 display shield with the tiny GPS connector also soldered on + EEPROM, I can sell you one unit at $30 (shield kit) + $10 (assembly+connector) +$7 (shipping). International shipping just went up the past couple of weeks šŸ™

      The 16X2 version is cheaper, $24 (kit) +$10+$6 but its display area is limited. If you want Time, EEPROM space left/latitude/longitude/altitude etc. the 20X4 display is great for it.

      Regarding programming, do you want the GPS coordinates displayed on screen and then press a button to save the current values to EEPROM, maybe with a time stamp from the real time clock or the GPS time code (if you’re in UK, it makes more sense to you since GPS all uses Greenwich time)? I can certainly do that for you. With the raw materials I already have (several project code) I think I can write the program for you within an hour ($100).

      let me know what you think.

  6. Johannes says:

    Hi Dr. Liu,

    I would need 2-5 (would start with 2) of your assembled 16×2 phi-2 shields together with face-plates (like this:
    When do you expect them to be back in stock again?
    I would be happy if you could contact me by E-Mail.

    Thanks in advance and best regards,


  7. Jerome Cloutier says:

    Hi Dr. Liu,

    I am building a project, and would like to use your menu system to replace my ugly switch case coded menu, I use a 4*4 keypad with a I2C pcf8574 expander so that I don’t use up all my I/O’s. Can you please point me in the direction on how to modify your lib’s to use the inputs from the I2C keypad. If you could email me I would greatly appreciate it,


    • liudr says:


      I didn’t personally make this type of mod to my library system but you are welcome to try. With your I2C keypad, are you able to get the key press (or no key press) by calling a getKey() function just like the most popular keypad library? If yes, you may be able to create a class that inherits from keypad class or just clone a class from matrix_keypad class and replace its key sensing functions with your I2C keypad’s version. I don’t have your expander so I can’t test code for you. I can give you some help still.

      An alternative to my menu system and I2C keypad is my phi-panel system that have the menu system integrated on its on board processor. Take a look to see if it interests you šŸ™‚—phi-panel/

      Everything is done by serial port and arduino sending text messages to the panel. There are panels with integrated keypads and backpacks on LCDs to connect to matrix keypads etc.

  8. Paul says:

    Hi I’m new to this. I have a vibroplex semi-automatic bug. If I buy the Phi-2 with the code software preloaded from you can I wire my bug into the unit and sent code displayed on the LCD?

    • liudr says:

      If the vibroplex semi-automatic bug can be driven by 5V signals, then the speaker output can drive it. Otherwise, you need some transistor to drive the bug. What voltage will drive the bug?

  9. Bob Katz says:

    Dear Dr. Liu: Your blog is a great resource! I’m just getting started with Arduino, but in a previous life decades ago I was good at embedded assembly language programming of 6502 and 8051 and I know my hardware and 74-series logic, so I’m not a complete novice. :-).

    I’m not sure how else to contact you so I’m asking on your blog if you please. Do you have a cover available for the Serial 20X4 LCD keypad panel – Phi-panel? I’ve seen a photo on inMojo but can’t find it again. With button caps, a hole for the LCD…. Do you have any left that you made, available to sell? Thanks! Bob Katz.

  10. Pingback: Phi-shield revised and released | Liudr's Blog

  11. Jon says:

    Hi mr liu , Iā€™m in admiration of the work you have done! Big props! I am in need of some help and a complete novice when it comes to most technological things so please take it easy on me šŸ˜„ my mind thinks more mechanically as I can see how things work to understand them. Your usb adaptor seems like it may be the perfect solution to a project I am starting and would just like to ask some questions to make sure I make the correct purchase. Many thanks I appreciate and look forward to your response.

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