Hi, in the pH sensor wiki page there´s a sketch to calibrate the sensor. However, I think there´s an error in the lines:

analogBuffer[analogBufferIndex] = analogRead(SensorPin)/1024.0*VREF; //read the voltage and store into the buffer,every 40ms


voltage = avergearray(pHArray, ArrayLenth)*5.0/1024;

The value "1024" should be "1023". Please check ASAP.

Hi bulcheter,

Thanks for your prompt.

We read here is that the voltage value of the PH. The output is 0 ~ 1023. Read from the sensors voltage value, its range in 0 ~ 1023, the value into 1024 pieces and then multiplied by 5V. So the value is 1024 indeed.

Thanks anyway.
By aaronblock2016
Hi Admin,

I am looking for a better understanding of your product, the IO Expansion Shield for Arduino V5.0.

This product supports both xbee and rs485, and I'm wondering if it does translation between them. I would like to plug an xbee chip into this board, and then wire it up to an rs485 Modubs RTU. By doing to this, could I send signals to the modbus RTU over xbee, using this board alone as the interface?

Hi Admin,
I have bought 3 piece of "12V 168P Gear Motor with Encoder", part no FIT0397 on amazon "SparkyKit". I have download the datasheet of the motor "FIT0397_45PA27G-45ZYT75-1245.pdf" on the website. draw out the part base on the drawing. after the design, I purchase the motor, 3 unit. It take some time for the motor to ship out, so I start my base plate and other part fabricate.
When I received the motor, there is one piece having some issue, so I got it replace. But when start to assembly, I found that the motor cannot fit into the base plate. I check all parts..
Finally I came to know that the motor and the drawing attached on the website is different, 20mm each, all together 40mm out!! the whole of the base plate cannot be use!!! it cost me USD400.
Now the question is, how can your company publish a drawing on the website and the actual one I received is such a big different, 20mm??
The base plate cost me USD400, I cannot throw away, the motor I bought 3 pcs, can return??
All the parts I fabricate is base on the motor spec, if I change the motor, I have to throw away the parts??
Please Help!!!
I have placed an order with you on 7th and my order is still in pending. It is not even processed. I am working on tight time schedule. It would be great if you can get back to me on expected time for delivery

Order ID is 158165

Dear dfrobot,
I have 9 v battery installed at my nb-iot sim-7000E!
But again i have it stuck on "TURN ON SIM-7000"
I am with cyta at a testbed nb-iot for Cyta that is working with other nb devices.
But i believe for sim-7000e to turn on network is not a factor? OR is it?
If the test is successfull nicosia will be full of dfrobot sim7000e . I am the guy that will make the city clever :)
Please check asap.
With my very best regards
Hi Admin,

I've recently purchased the 800x1280 HDMI display and I'm having trouble getting it work.

I've tried it with a raspberry pi 4, a Khadas Vim3, a beaglebone black, a PC running Linux and MacOS. None of these are outputting anything to the display... it's getting power (the backlight turns on when it's plugged into the USB port on the device) but that's it.

Am I missing something with the setup or could the display be defective?