UART pins in BCM mode are: 14, 15
UART pins in WiringPi are: 15, 16
UART is an asynchronous serial communication protocol, meaning that it takes bytes of data and transmits the individual bits in a sequential fashion.
Hello everyone. Today I found a very nice tutorial to enable UART (GPIO) serial on Raspberry Pi 3 and Pi Zero W. To summarize, here are the commands I did to enable serial (/dev/ttyS0) on. Most machines, even very small machines, still have a serial interface somewhere - the Raspberry Pi has two! A serial port provides a way of connecting devices together and provides a reasonably fast communication channel that can be used over a larger distance than most other connections such as USB.
Asynchronous transmission allows data to be transmitted without the sender having to send a clock signal to the receiver. Instead, the sender and receiver agree on timing parameters in advance and special bits called 'start bits' are added to each word and used to synchronize the sending and receiving units.
UART is commonly used on the Pi as a convenient way to control it over the GPIO, or access the kernel boot messages from the serial console (enabled by default).
It can also be used as a way to interface an Arduino, bootloaded ATmega, ESP8266, etc with your Pi. Be careful with logic-levels between the devices though, for example the Pi is 3.3v and the Arduino is 5v. Connect the two and you might conjure up some magic blue smoke.
Assuming you have WiringPi-Python installed, the following python example opens the Pi's UART at 9600baud and puts 'hello world'
Details
|
Turning off the UART functioning as a serial console
See the instructions here.
Setup Permission
You can determine the user PHP is running as with this command in a php page:
It will typcially be 'www-data'. All serial connections, virtual or physical, are owned by the 'dialout' group so if you add www-data to the dialout group your PHP scripts will be able to open/read/write the UART (or other serial devices). The following command will add the group to www-data.
You can confirm this with:
You now need to restart the RPi for the setting to take effect.
Transmit A String
Include this in a php page, load the page using a browser and you should see the data being sent out of the UART TX pin.
If you want to include variables:
We benefit hugely from resources on the web so we decided we should try and give back some of our knowledge and resources to the community by opening up many of our company’s internal notes and libraries through mini sites like this. We hope you find the site helpful.
Please feel free to comment if you can add help to this page or point out issues and solutions you have found, but please note that we do not provide support on this site. If you need help with a problem please use one of the many online forums.