Project Background

During development / research for a project which needs more than 1 UART Port, the common replacement for the Raspberry Pi is the "Arduino MEGA". This is because the MEGA provides 4 UART's which can be used at the same time creating a multi UART device.

When using UART on the Raspberry Pi you are very limited on how you work around this limitation, but we also know that the Pi 3B has a built in WiFi & Bluetooth module. In the Raspberry Pi 3B the Bluetooth uses the only UART which further limits the use of the Pi.

Most solutions for External UART controllers come as a USB to UART converter, which takes up space and brings the design out of the Raspberry Pi's small form factor. To counteract all the limitations of the Raspberry Pi, we have built a board which simply connects through the Pins on the Raspberry Pi as usual, but include access to extra UART's without limiting the Pi any further or without a special image. Included is our own software which manages, controls, and watches the UART ports.

The software comes as a terminal program, and multiple GUI programs, each will report the port location for easy to use manageable hardware integration.

WHAT IS IT?

UART HAT is Add-on board for Raspberry Pi which provides one/ two/Four additional RS232 & TTL serial ports with flow control which are 3.3 V compatible in addition to the original Serial Port of Raspberry PI.

WHAT IS THE USE OF UART HAT?

As we know the Raspberry Pi only has one Serial Port with only one RX and TX, which is primarily used for Debugging and SSH. If we need to connect any serial devices to Raspberry Pi we have to disable debugging and then we need to connect our device. So if you need to connect up a UART device such as a GPS or GSM Modem, you cannot SSH or debug the Raspberry Pi with a serial connection. To overcome the all these problems we have came up with UART HAT which helps to Connects Multiple Serial Devices Like GPS, GSM Modem, Bluetooth 2.0/4.0 module , Arduino Pro Mini, Arduino serials and whole array of devices to Raspberry Pi main board without using the main RX, TX pins on the main board.

Serial Port device list

I2C to UART HAT board from 1 UART to 2 UART up to 8 UART

1. 2uart-Pi-Ze plug in Pi Zero

2. 2uart-Pi-Ze+2uart-232-485-m01 Module plug in Pi Zero

2uart-Pi-Ze-Li demo

3UART demo ( 2 - 2uart-Pi-Ze-Li,1 - Pi)

1. Arduino Mini Pro 2 Bluetooth 2.0 3. Bluetooth 4.0 BLE (Pi)

UART Pi Zero HAT plug in B+/ 2B / 3B

4UART products can use up to 8 UART in one Pi

4uart-ext board with 4uart-232-485-m01

1. 4 UART Pi (4 UART TTL output /HAT EEPROM) with Extension socket

1a. 4 x RS232 /4x RS485 Extension module

1b. 4x. RS232 Extension module

4 UART HAT demo

uart1, uart3, uart4  arduino mini Pro x3 Bps: 9600

uart2 bluetooth 2.0 x1 Bps: 38400

9UART demo  8 UART ( 2x 4 UART HAT )+ 1 UART Pi

Pi-UART-4-TTL ( 4 UART HAT ) Pi-UART-4-TTL ( 4 UART HAT ) Raspberry Pi 2B Pi-PSU ( Pridopia Pi Power Supply ) SIM908-C EVB 1.0 GPRS+GPS Module ( 2 UART ) ESP8266WiFi module ( 1 UART ) Bluetooth 2.0 ( 1 UART ) Pi-HAT-Lite GPS Module ( 1 UART ) Bluetooth 4.0 BLE ( 1 UART ) arduino mini Pro ( 1 UART  Pi ) arduino mini Pro ( 1 UART ) arduino mini Pro ( 1 UART )

1. SIM908-C EVB 1.0 GPRS (Port 8 bps 115200 )

2. SIM908-C EVB 1.0 GPS  ( Port 7 bps 115200 )

3. Bluetooth 2.0 ( Port 6 bps 38400 UART )

4. ESP8266WiFi module ( Port 5 bps 115200  )

I2C to UART HAT board from 1 UART to 2 UART up to 8 UART

 RS232 DB9 output example

Example 1

Needs 3 UART Signals to control 1 GPS board & GPRS, and GPS board.

Example 2   

GPRS connect to Pi UART & GPS connect to 1 UART HAT

Example 3 

Bluetooth 4.0 BLE ( 1 UART ) Bluetooth 2.0 BLE ( 1 UART ) ESP8266 WiFi Module ( 1 UART, Using Pi RX/TX Signal ) Pi-UART-2-TTL ( Provides 2 UART ) Raspberry Pi 2B Raspberry Pi-PSU ( Power Supply to boards )

1a,2a  GUI Interface for Serial Port Monitoring & Control

1. Cutecom Status for UART HAT Port 1 ( Bluetooth 4.0 BLE 9600 Baud )

2. Cutecom Status for UART HAT Port 2 ( Bluetooth 2.0 BLE 9600 Baud )

3. Cutecom Status for Pi UART ( ESP8266 WiFi Module 115200 Baud )

Use Raspbian Jessie Image
Version: May 2016 - Release Date 2016-05-10 Kernel Version : 4.4

Enable I2C & SPI, Disable Serial Console Port

Install Python SMBus and Cutecom;
sudo apt-get install python-smbus sudo apt-get install cutecom i2cdetect -y 1 ( and detect what address your chip is on )

Automatic Login for LightDM

Open a file browser or terminal and direct yourself towards /etc/lightdm/
Now backup the lightdm.conf to your desktop just incase things don't workout. Uncomment the lines;
autologin-user=USERNAME
autologin-user-timeout=0
Replace the USERNAME with your username ( pi or root )
Ctrl + X then Y to save in the nano editor Run the command so that the changes take effect;
dpkg-reconfigure lightdm Serial Interface / Control Panel

1. GUI Serial Port Interface / Control Panel
2. GPRS Cutecom Terminal ( SIM908 GPRS 115200 Baud, Pi UART )
3. GPS Cutecom Terminal ( SIM908 GPS 115200 Baud, I2C UART Port 2 )
4. GPS Cutecom Terminal ( HAB-Lite GPS Module 9600 Baud, I2C UART Port 1 )
5. Cutecom Shortcut
6. Java PiCom Serial Port GUI Shortcut
7. I2CDetect detecting 0x48 I2C UART Board

Serial GUI Control Panel
Control up to 8 Serial Ports

              Chip Address Location, Channel Number ( 1 / 2 ), TX and RX receive counter,

              and Serial port Location /dev/pts/X

Also provided is a terminal command mode to activate serial ports through a terminal / ssh.
You can also activate a serial port on boot up with the provided software.
Commands for starting the serial ports via command line;
./Pi8s -a ADDR -c CHANNEL -b BAUD -s DEVPTS
ADDR = Address of Serial Port e.g. 0x48, 0x49, 0x4C, and 0x4D
CHANNEL = Channel of serial Port ( 1 / 2 )
BAUD = Baud Rate for the Serial Port
DEVPTS = PICOM Service Number ( Will direct the filename to /dev/picomX where X = your number )

For example, To start a serial port from 0x49, on channel 2 with 115200 Baud run the following;
./Pi8s -a 0x49 -c 2 -b 115200 -s 1
This will activate the serial port and then set /dev/picom1 to your serial port location /dev/pts/X