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The ESP WiFi Shield: the best value for money and low energy consumption

The ESP WiFi Shield: the best value for money and low energy consumption

The body section simply contains the veritable request, while the header section contains the “HOST:” header, in our case. As an example, here is a request for weather conditions, that is carried out by sending the following: “GET /data/2.5/weather?id=3164699 HTTP/1.1 HOST:”

The request must be sent after that, obviously, we connected to the server by means of the instruction:  “AT+CIPSTART=”TCP”,””DEST_HOST””,”DEST_PORT”rn”

All of the examples have been tested with modules having a 09.02 firmware version, that turns out to be the most stable one, and the one that is free from bugs; at the moment there isn’t yet a final firmware version, and on the Internet it is possible to find even more recent versions, but that are yet to be tested. It is however possible to install a different firmware version, by means of a simple procedure that we will now describe. Among the files in this installment you will find a folder named firmware, that contains an executable file named ESP8266_flasher.exe, which is used in order to load a new firmware on the module; we already made a firmware version 09.02 available, that you will normally find installed in the ESP8266-01 modules.

Once the software has been started (it does not require installation), it is enough to specify a COM port to be used for the communication with the module and to open the .bin file; in order to know which serial to use, you may use the information provided by Arduino’s IDE when the Arduino board is connected. Please set the module in the communication mode with the PC and enable the module’s boot mode, by placing the GPIO0 line to ground by means of a jumper cable, afterwards please reboot the module by placing the CHPD line at a low level for a moment, even here a small jumper cable will be enough. After the reboot, the module will be set in boot mode, ready to receive the new firmware. Please click on the Download button, then, in order to activate the loading and wait for the operation to be concluded. Please use the AT+GMR command in order to verify if the module is operating correctly and which firmware version has been installed.


SD-Card Classification

There are different SD-Cards available for sale, and they may be distinguished because of the technology used, that evolved in the years, starting from the basic SD Card. Not all of them are compatible with the other ones, even though the manufacturer tend to generally keep the backward compatibility. The various types are described as follows, one by one.


SD capability, going from 128 MB to 2 GB.

Default Format: FAT16.

The SD cards operate in all the host devices supporting SD, SDHC or SDXC.



SDHClogoSD High Capacity (SDHC ™) is a SD ™ card, based on the SDA 2.0 specifics.

Capability going from 4GB to 32GB.

Default Format: FAT32.

Since SDHC operates in a different way from standard SD Cards, this new format is not compatible with the host devices supporting only the SD ones (128MB – 2GB). The greatest part of the readers and host devices that have been built after 2008 should be compatible with SDHC.

In order to guarantee the compatibility, please look for the SHDC logo on both the boards and the host devices (cameras, etc.).


SDXClogoCapacità SD Extended (SDXC ™) is a SD ™ card, based on the SDA 3.0 specifics.

The SDXC capabilities may vary from 64 GB to 2 TB.

Default Format: exFAT.

Since the SDXC uses a different file system – named exFAT – and since its functioning is different from the SD standard cards, this new format is not compatible with the host devices that only support the SD ones (128MB to 2GB). The greatest part of the host devices that have been built after 2010 should be compatible with the SDXC. In order to be sure of the compatibility, please look for the SDXC logo, both on the boards and on the host devices (cameras, etc.).

NOTE: card readers that are found inside laptops, starting from 2008 (and before) may NOT support the SDXC cards. The SDXC cards operate only in readers that are compatible with SDHC (not the SD readers) and if the computer’s operating system supports exFAT.


Having a SD available for the purpose of saving data enables us to create an interesting data logger that has the function of accessing the Internet network, in order to find useful information. In the case of a data logger, a surely important data is given by the date and time in which the data is saved; a function usually carried out by a RTC (Real Time Clock) that is interfaced with Arduino. Having the possibility to access Internet, it is easy to query a NTP server, in order to know the accurate date and time, without the need to execute any initial setting. A first simple test – in order to verify if anything works correctly – consists in inserting a SD card in the slot (a micro SD, to be accurate) and to execute the cardInfo.ino sketch, that is available among the system samples; please make sure that the SDCS jumper is in the D4 position. You may see from the images the answer displayed on the Serial Monitor, concerning a SD HC cat4 having 8GB and FAT32 formatted, that we used for our tests. With the ReadWrite.ino sample you may verify if the reading and writing function are working properly.


New firmware installation.

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