Patrice Godard's Circuit Sculpture Is a Standalone or Peripheral LED Matrix, PCB-Free
Integrated Microchip ATtiny85 allows this sculpture to run as is, or it can be switched off in favor of an external microcontroller.
Software engineer and maker Patrice Godard has designed an addressable LED matrix with a difference: it uses through-hole parts arranged in a freestanding circuit sculpture.
"I like the game of patience that is building circuit-sculpture style circuits," Godard explains of the project. "I enjoy the planning, the trials and errors that often make the end result quite different from the plan. "I'm also a fan of the so-called SuperComputer Panel that BigClive has on some of his YouTube videos, and I recently made an Instructable with various software implementations of this blinking led panel. So I decided to combine both. I wanted the LED matrix to be autonomous and I had a [Microchip] ATtiny85 laying around. This is more than enough to run the software while being… tiny!"
LED matrices are nothing new, but their typical modern implementations rely on machine-positioned surface-mount LEDs on a PCB. Godard's version has no PCB at all: instead, through-hole LEDs have their legs bent and soldered to brass rods to form a stiff freestanding circuit hovering in mid-air.
Below the matrix itself are the other active components, likewise supported only by the brass rods that double as circuit traces: a Microchip ATtiny85 microcontroller, an Analog Devices MAX7221 LED driver, six diodes, four resistors, and two capacitors. A 3D-printed jig aided with assembly, and the entire sculpture rests on a base of wood.
"The ATtiny85 is driving the MAX7221 via SPI, using the LedControl library," Godard explains. "I wanted to be able to use the matrix with an external more powerful MCU [Microcontroller Unit] too, so I designed the SPI and CS connections so that they could be shared. This required diodes between the output of the MCUs and the inputs of the MAX7221, as well as pull-down resistors on the Max7221 inputs. [A] micro slider switch is used to power-off the ATtiny85 when an external MCU is used."
The project is documented in full, along with source code and 3D print files for the assembly jigs, on Instructables.