TL's elektronik ting og sager
USB TTL WiFi HUB
This all-round HUB is made so it can be used for most of my projects where communication between the PCB's, WiFi network or USB (PC) is required. Almost all the PCB's I make have two standard TTL communication ports, an input and an output port. I have made it so it is a bit like a RS485 parallel bus, but just with TTL signals. These TTL signals are only to be used internally inside an enclosure to communicate between the various PCB's. Externally, the communication must be of a different type, e.g. USB, WIFI or a RS485 industry standard bus. High speed TTL signals are not usable for long distance communication. This HUB can be connected to all my PCB's with these ports and convert the data to either WiFi or USB.
For WiFi communication I use an ESP12 module which is configured as a MESH access point. This means that communication can take place wirelessly and that all data is transparent between all the modules on the bus. All devices can hear each other. The system is made so there is a Master (PCB or PC with special software) who is responsible for the overall communication. The master sends request commands to all the slaves on the network who then reply back if asked. In this way, all the modules can send data, one by one to the master. This kind of communication just requires that there is only ONE Master who controls it all, otherwise data collisions may occur. In some of my designs, if they are not running on a larger network, the master may be a main PCB, and in other cases it may be a special designed Windows program which is the master.
Here are the data sheets on the ICs I have used on the PCB
Here's the finished PCB.
Here's the PCB layout. It is a 4-layer FR4 and measures only 46x46mm. The ESP module is a type with an external antenna connector so it is possible to reach long distance communication.
Top layer - generel routing where it is possible.
Inner layer 1 - unbroken ground plane.
Inner layer 2 - unbroken power plane. 3.3Vdc.
Bottom layer - additional routing.
Here's the schematic for the HUB.
How to use the FT230XQ - just plug it in and a new virtual com port is popping up in the Windows Device Manager. Now ready to use. Nice and easy.
