Raspberry-Pi Rev 3
On the Raspberry-Pi 3 the auxilliary (or mini) UART port has been used to control the Bluetooth device. As a result all add-on cards which use the UART no longer work. For example xbee and other transmitters, RS485 and unfortunately also the gertbot. There are several threads about this:
SolutionI found that the following worked for me on the latest stretch image:
- Add to the /boot/config.txt file: "dtoverlay=pi3-disable-bt"
- Remove "console=serial0,115200 console=tty1" from the /boot/cmdline.txt file
Do NOT enable the UART using the Pi configuration GUI !!
For editing /boot/config.txt and /boot/cmdline.txt you need 'sudo' plus an editor (sudo nano /boot/config.txt, sudo nano /boot/cmdline.txt)
As this swaps the mini UART back to pins 14 & 15 on the GPIO connector, the Bluetooth functionality is lost.
Thus it is not possible to use gertbot and Bluetooth at the same time.
I have heard that some people managed to use the software (bit-bang) UART emulator on pins 14 & 15 alongside Bluetooth. Thus far I have not been able to get this working with the Gertbot. Probably because (Just as with e.g. xbee) the gertbot data is a packet oriented stream with no buffering and binary data and the gertbot driver changes the echo, cbreak tty settings.