Hello,
I am new to this Group, this is my first post.
I would like to use two DT-06 WiFi-TTL-s on my project, one transmitting and the other receiving ASCII characters. The receiving DT-06 would output the data to an Arduino Nano, which will process it and drive a stepper motor to a predetermined angle that corresponds to the received character. It works fine when I input ASCII from my PC to the Nano.
I have 3 pieces of DT-06, complete with a web server. Tested all 3 units, they show up on my cellphone with an interface where I could change Baud rate, etc. The documentation inclines that they are ready for data communication and they would work as a wireless modem. My problem is that when I connect the USB to serial interface from the PC, the TX pin of the DT-06 is sourcing too much current and my USB to serial interface cannot pull the TX pin any lower than 2.8V. This is confirmed by looking at the wave form on a scope. All 3 boards I have, behave the same way. The Vcc to DT-06 is 5V and the USB to serial interface is of the 3.3V version. What I am seeing is typical when an input has a hard internal pullup due to configuration problem and this is what prompts me to ask.
My question to the experts on the Forum who have used DT--06 in this way is: Do I need to flash an application to the DT-06 to be able to use it as a wireless modem?
Apologies if this is the wrong Forum, but I could not find any similar DT-06 H/W description here or on the web. The data sheet only mentions a 22Ohm internal resistor in series with the pins.
Please have a look through the forum instructions posted in "How to get the best out of this forum", linked at the head of every forum category.
Forum members need to see links to the product pages or data sheets for all the devices you are using and a wiring diagram (hand drawn is preferred, with all pins, parts and connections clearly labeled).
Also state which Arduino you are using -- there are half a dozen versions called "Nano"
I wonder if you trying to connect I/O pins on a 5V Arduino to I/O pins on a 3.3V device without using logic level shifters.
If you have Tx connected to Tx and Rx connected to Rx it will do what you are saying. Tx always connects to Rx, and it is not a party line. If it is wired this way post an annotated schematic showing exactly how you wired it and include links to the hardware items technical information. Please follow @jremington advice and follow the forum instructions.
Also explain how you determined it is drawing high current.
To @gilshultz: It is not clear from the DT-06 Manual whether the device is DTE or DCE. If the device is a 'DCE' then the data I want to transmit has to be connected to 'Transmit Data TXD' and if it is DTE then it goes to 'Receive Data RXD'. At first, I connected the data to 'TXD' of the DT-06, thinking that "this is the data I want to 'transmit' ". Indeed, this was a problem. The high current draw was obvious when I looked at the collector of Q2 with a scope. The level was about 3.2V without sending data to it. With data, Q2 was only able to pull the 'Data out' pin down to about 2.9V, hence the determination that there must have been high current sourced by the pin in question.
Connecting the data from the Level converter to the 'RXD' pin of the DT-06 resulted in excellent waveform at Q2 collector. Please see attached schematics. Wireless RS232 port extender.pdf (195.4 KB)
I have two more DT-06's and replaced both the transmitting and receiving modules. None of the modules is producing any data output on the 'TXD' pin (RX TEST POINT) of the DT-06 receiver module and all three produce a nice webpage that I can access at 192.168.4.1.
So, my original question remains the same: Do I need to flash an application to the DT-06 to make it work?
Thanks for reading it!
The "UserManualFor DT-06" does not make clear the function of pins named TXD and RXD pins. They are just two GPIO pins, and their actual usage depends on what firmware is uploaded to the DT-06. See data sheet excerpt (image) below.
The data sheet for the "DB-06 WiFi/RS232" module is also not helpful with regard to nature of TX and RX. The documentation you have linked is very poorly written (or translated) and is incomplete. I can't make much sense of any of it and suggest that you contact the seller for the details.
Note: the picture of the DB-06 states I/O level 3.3V. You MUST use logic level shifters to connect I/O pins on a 5V Arduino to I/O pins on a 3.3V module. Failure to do so can damage both connected devices, and at the very least. will almost always lead to malfunction.
Thanks @jremington, I agree that the Manual is poorly written. I was hoping that the unit is ready for wireless RS232 transfer as-is because it does have a built-in webserver. If the S/W Developer comes this far, then why not make the unit fully functional. If I have to get an API from the Manufacturer and have to write code for it, then might as well find another WiFi RS232 extender.
Correct on the level shifter, that's what the circuit is doing. It also flips the logic level from standard RS232 to positive TTL logic.
I hope that someone will confirm that an app needs to be flashed on the unit to make it work, or points me to another solution.
Regards,
You should NOT assume that RS232 inverted logic levels or voltages are used with the DT-06. That adapter is for legacy RS232 serial devices that utilize +/- 12V logic.
Or is there such an antique in your project that you forgot to mention? If not, and you connected it to the DT-06, then the DT-06 I/O pin circuitry may have been destroyed.
Why have you not posted the requested circuit diagram?
It is not that I forgot to mention the legacy RS232, it is clearly shown on the schematic. Yes, I have such an old antique item in my junk box, but this is besides the point. Let us settle with the fact that the signal going into the DT-06 does have the proper 3.3V swing, where 3.3V is logic 1 and 0V is logic 0.
The point I am trying to get across, is that I cannot get the DT-06 going, never mind the legacy USB232 Plus1.
Here is an update concerning my post about DT-06 module not working. The high current draw on the RX pin was due to my swapping of TX/RX pins. It was an easy fix and the unit's web server was working fine. Communication between two modules still did not work. Searching the web did not yield any useful and detailed description on how to establish a UART-like communication between the two units.
My brother is a Network Engineer and we managed to solve the problem. The solution we came up with is detailed in the attached document. We hope that it might just help others who had similar issues. The setup uses a WiFi Router to increase the range. Unit to unit direct connection does not have the range I need for my application. DT-06 pair configuration.pdf (907.6 KB)
