Further to our posts on the ESP-01 we now have developed a ESP-01 based star system model where we have a central server and soft access point that generates a WiFi network . We have clients that are also based on other ESP-01 modules that can connect to this network ( as many as needed to a reasonable extent). This system now allows us to build a star system of WiFi modules that can be used to sense/control devices connected to the individual modules. More to follow. Please visit the Signal Processing Group Inc. website for more information about us and other articles of interest.
We continue to develop more and more applications using the ESP-01. Connect to the Network and become an access point for other clients to connect to. A key part of this understanding was the successful inclusion of the header file ESP8266Wifi.h. This file was creating errors in program compilation until we finally understood how to stop these from occurring. Once that was done the process of developing applications became a little easier. The issue we are grappling with now is the provision of the power supply in the case of a standalone battery powered application. We will be reporting on that in subsequent posts. Please visit the Signal Processing Group Inc. website for more technical information.
Here is another interesting finding from our experiments with the ESP-01. We got stuck on a number of files whenever the file had ESP8266WiFi.h in it. While compiling the error was “Error compiling for board generic ESP8266 Module”, After some frustrating days we found ONE fix that seemed to work. This is to go to the “tools” menu in the Arduino IDE and make sure that the Debug port is “Serial” and the debug level is “WiFi”. At least that seemed to work for us. More ESP-01 blog posts to come as we work our way to a better understanding of this product. Please visit the Signal Processing Inc. website for more technical info.
The ESP-01 is a very small RF / uC module capable of WiFi operation standalone, or as part of an embedded system. It is very popular and we decided to take a look at it and it proved a fascinating study so far.
However, it is not easy to use and will frustrate a person unless that person has a lot of patience. There is a lot information about it available on the web, both textual and Video but in most cases this can only be used peripherally as the ESP-01 can be difficult to manage and use.
The software component of this product is the Arduino IDE which is a big help. Here are our observations after a few days of experimenting with the ESP – 01. (1). You have to get a good programmer so that programming will not be that painful. I have been using a standard programmer, i.e. a USB to TTL ( and vice versa) device that is both cheap and freely available. See the picture below.
However it is important to modify its physical construction somewhat. (a) Connect a switch between the GPIO0 pin and ground because the programming will require that configuration and the programmer does not provide it. (2) Connect the CH_PD pin to VCC. (3) Connect a pushbutton switch from RESET to GND. This is important. When programming the GPIO0 switch has to be in the GND position and the RESET pin must be pulsed.
Beyond this the programming is quite painful and one must be prepared for many failures and frustrating days. What we want to do is try to journal as much as we can in this blog to help.
A simple way to estimate delta sigma parameters of number of bits and oversampling rate etc. is presented in this brief paper on the Signal Processing Group Inc., website. Please visit and check under the ” complementary” menu item.
The bridged T attenuator was described in an earlier post. This calculator can be used to calculate the resistor values for it quickly and efficiently. Please visit the Signal Processing Group Inc., website and the “complementary” menu and find the calculator.
The bridged T attenuator is another simple attenuator with some advantages such as simplicity of implementation and control of attenuation levels by simply changing a resistor value or making it continuously variable. Please visit the Signal Processing Group Inc. website and click on the “complementary” menu item and select the bridged T attenuator topic to read more about this attenuator.
The resistors for pi type asymmetric attenuators can be calculated using the javascript calculator available in the Signal Processing Group Inc., website under the complementary menu item. Please visit the website for the calculators and more technical information.
As mentioned in a prior post the pi attenuator can also be used in an asymmetric configuration where the I/O impedances are quite different. In this case we need to use the asymmetric form of the attenuator. Please visit the Signal Processing Inc. website and look up the information on the asymmetric pi pad ( attenuator) under the complementary menu item.
Another important and useful network that is used extensively is the pi type symmetric attenuator. It has equal I/O impedances and presents its terminal impedances in shunt. Please visit the Signal Processing Group Inc., website for more information on this very useful network and its design equations.
