Sawppy: Raspberry Pi 4B
Yesterday, we put a little work into tightening up all the joints on Star (our family’s Sawppy Rover build). After a reasonably long test drive of about 30 miutes, there were not discernable issues with loose set screws on the wheel and steering shafts.
Not having to tune up drive parts afforded me some time in the evening to replace the Arduino Nano-based Joystick control board we’d been using. The new Raspberry Pi 4B/2GB board had just arrived this week, so this was the perfect opportunity.
Powering it Up
Powering the Raspberry Pi after installation in the Rover was pretty simple. I already have a DC/DC Buck Convertor powering the Arduino board. It takes the LiPo battery power from the 2S battery pack (ranging 7.4-8.4V), and steps it down to a voltage acceptable to the control circuitry.
I just needed to make sure the output was set to 5V for the Raspberry Pi, and connect it to GPIO pins 1 (5V), and 3 (GND) on the Raspbbery Pi. It booted as soon as I turned on the power, and there were no under-volt issues reported in the system logs.
Before powering the board up on the rover, I needed to do some intial setup at my desk. It would have been difficult to get a monitor and keyboard hooked up to the rover chassis so I could run the first commands to enable SSH, join the WiFi network, etc.
I’d hoped to power it at my desk from my MacBook’s charger, but because the USB-C connector on the RPi 4 is non-conforming, it didn’t work with any of the USB-C to USB-C cables I have. So I had to rob a wall wart power supply from another running Raspberry Pi in my office to get it started.
Once I’d sorted out power, everything else was a breeze. Using the
command, I set the keyboard locale, WiFi settings, changed the hostname to the
somewhat whimsicle name “star-rover”, and so on.
The only other minor hiccup I had was that I tried to configure it to connect to my 5GHz network, but that doesn’t appear to be supported. But since my router is Dual-Band, I just used the regular 4Ghz SSID and everything was good to go.
Connecting the BusLinker Board
The last thing I needed to do for physical hardware setup was connect to the Micro-USB port on the LewanSoul BusLinker board.
It’s using a CH431 USB-UART chip onboard, which is supported by the Raspberry Pi OS without any additional drivers.
The only challenge I had here, was actually finding a short enough USB cable that wouldn’t be awkwardly-long.
I have plenty of little Micro USB cables around, but many came with devices that only need it to charge a battery, and a lot of these only have 2 wires attached to the connector to make them cheaper. Very few of these actually have any marking to indicate that they don’t support data, so it took some trial-and-error to pick the right cable.
But once I had the right one, the BusLinker connecting showed up in
lsusb -t so I knew all was good to go.
I have some chores to do today before I can pick up where I left off, but I plan to install the original interface that was used by Sawppy Rover.