GARETH HALFACREE’S
Hobby tech
The latest tips, tricks and news in the world of computer hobbyism,
from Raspberry Pi, Arduino, and Android to retro computing
R
egular readers will remember the
launch of the BBC micro:bit (see
Issue 154), a low-cost education-
focused microcontroller board that formed
the centre of a revived computer literacy
programme at the nation’s oldest broadcaster.
The rather clunkily named BBC Doctor Who
HiFive Inventor Coding Kit is not, surprisingly, a
new BBC micro:bit pack, but an entirely new
device – based unabashedly on its seemingly
departed predecessor.
Like the micro:bit, the HiFive Inventor – put
together by SiFive – has two front-facing
tactile buttons and an LED matrix, as well
as an accelerometer, magnetometer and
thermometer as embedded sensors. The spec
has had a bit of an upgrade though: the 5x5 red
LED matrix of the BBC micro:bit is now a 6x8
RGB matrix; the radio now supports Bluetooth
4.2, Bluetooth Low Energy (BLE) and Wi-Fi; and
there’s a real light sensor, rather than relying on
a hack with the LEDs.
There’s also a new processor. The heart of
the amusingly hand-shaped board is a SiFiveFE310, which packs two 32-bit
150MHz processor cores based on
the free and open-source RISC-V
instruction set architecture.
There’s also 64KB of static
RAM (SRAM) and 512KB of
QSPI flash.
The FE310 isn’t the only
processor though. Flipping
over the Inventor reveals an NXP
Kinetis K22F with an Arm Cortex-M4 core,
which handles the micro-USB interface and
debugging. Next to that is a bulky Espressif
ESP32-SOLO-1 module, which provides
802.11b/g/n Wi-Fi and Bluetooth, while
bringing across its own single-core Xtensa
processor – and considerably more SRAM and
flash than you’ll find on the main board itself.
This piecemeal approach, which feels like
it exists to make up for shortcomings in the
FE310 chip and suggests the whole board
may have been better off just running from
the ESP32, is extended to the edge connector
at the base. It duplicates the BBC micro:bit’sversion pin-for-pin, but only based on the
original design. The indentations that help
crocodile clips stay in place, for example, which
were added to the latest BBC micro:bit revision,
are nowhere to be seen – the same goes for
the new touch sensor and microphone.
There’s a simple explanation for this. The
HiFive Inventor is actually the SiFive HiFiveREVIEW
BBC Doctor Who HiFive
Inventor Coding Kit
CUSTOMISATION / HOBBY TECH
It’s not hard to see the BBC micro:bit’s
influence in the HiFive Inventor’s design,
despite the hand-shaped PCB