Building a Mini 7-Segment Clock (V2)

Kevin Rye recently re-designed his already impressive Mini 7-Segment Clock using an SMD version (instead of 28-pin DIP) of the ATmega328 microcontroller (MCU) and a custom PCB.

“I moved the switches a little off-center to the right and shuffled everything else around in order to fit the SMD ATmega,” Rye explained in a recent blog post.

“I rotated the ATmega 45 degrees. I think chips look cooler when they’re rotated, but in all seriousness, it is easier to run a trace from one side of the board to the far side of the chip when it’s rotated.”

Rye also moved most of the (PCB) text from the front to the back. However, with the exception of the ICP and FTDI headers, the board layout remained the same.

 After receiving his new PCBs, Rye decided to kick off a limited test of his new design.

“I didn’t want to put the whole thing together and find out that it didn’t work, [so] I decided to only solder in the ATmega, the 16MHz crystal, and the supporting caps and resistors – just enough so I could test loading the bootloader onto the ATmega and upload a sketch,” said Rye.

“I configured my Arduino Uno (ATmega328) as an ISP and attached the Mini Clock’s 6-pin ICP header to the Arduino via a ribbon cable and some jumpers. I then jumped into the Arduino IDE and burned the bootloader for an Uno.”

After successfully running the bootloader, Rye connected the FTDI adapter and uploaded the blink sketch, jamming an LED into the PCB and watching the LED blink. Last, but certainly not least, Rye validated the ICP and FTDI functions and soldered in the rest of the components.

Interested in learning more about version two of Kevin’s Mini 7-Segment Clock? You can check out his detailed project blog post here and download the source files here.

LED SMD firefly built around an ATtiny85

A Maker by the name of Tyson has created an “electronic firefly” built around Atmel’s popular ATtiny85 microcontroller (MCU) and a custom PCB.

Additional project components include:

• (2) 12 pf 0805 capacitors
• (1) 100 kOhm 1206 resistor (for reset line)
• (1) 1 MOhm 1206 resistor (for LED discharge)
• (1) CR2032 battery holder (BC2032-E2 at Digi-Key)
• (1) CR2032 battery
• (1) Clear Orange 5mm LED (754-1271 at Digi-Key)
• (1) 32 kHz crystal (535-9166-1 at Digi-Key)
• (1) 8 to 12 oz Mason Jar
• 2-3 oz sand

Before kicking off, Tyson reviewed Karl Lunt’s asynchronous fireflies project, with the overall goal of simulating intermittent blinking in low-light conditions like a firefly.

“Using the existing project, I did need to modify a few things. First off, I was using an ATtiny85 instead of the ATtiny13a, as well as an external clock,” Tyson explained in a recent blog post.

“Luckily, the external clock only required a few fuses to be set as far as programming went and a couple load capacitors to allow it to be used with the MCU. The ATtiny85 required a few code changes because the output port for the LED and mux for ADC had to be changed among other registers.”

In terms of the PCB, Tyson used photo paper for the print and Eagle to create the necessary traces. He then soldered on the ATtiny85 and set the appropriate clock speed.

Interested in learning more about building LED fireflies with Atmel’s ATtiny85 MCU? You can check out HackADay’s coverage here, the project’s blog page here and the source/board schematics here.