Tag Archives: DS1307

Walltech SmartWatch tick-tocks with Atmel

After successfully designing and extensively documenting the open source OLED Watch (v 4.2), Walltech founder John Wall has moved on to version 6.0 of the Atmel-powered smartwatch.


The latest wearable device is built around the FemtoduinoBLE, which features an ATmega32u4 microcontroller (bootloaded as an Arduino Leonardo) paired with a BlueGiga Bluetooth 4.0 low energy module to link devices and receive notifications.

The newest Walltech also boasts a 1.5-inch full color OLED display as well as an on-board microSD card slot.

“A step up from the monochrome .96′ OLED display of v4.2, this screen also consumes very little power thanks to the OLED technology behind it and can show beautiful images that will be the GUI for the smart watch,” John explained in a recent blog post.

“Now that there’s an SD card on board, I can use fancy graphics and make it look professional and keep the code to the MCU, enabling more to be coded instead of storing images too.”

In addition, says the designer, the DS1307 and accompanying regulator make an appearance again, with the same battery charging IC from the previous model powering up the 500mah lithium ion battery.

“To make selections, there will be a surface mount three-way navigation switch in the top right that you can flick up, down and push in to make selections and scroll through faces and apps,” he added.

Interested in learning more? You can check out John’s completed OLED Watch (v 4.2) here and the Walltech Smart Watch v6.0 introductory blog post here.

Interfacing with Adafruit’s Atmel-powered Trinket

Bits & Pieces recently covered a project by a Maker named Pocketmoon who wanted to demonstrate just how many components can be hung off Adafruit’s 3.3v ATtiny85-powered Trinket.

Today, we’re going to be taking a closer look at constructing a Trinket RGB shield clock, courtesy of the Adafruit crew. 

According to Adafruit’s Mike Barela, the project was inspired by a forum member who asked if the Trinket can be interfaced with an RGB LCD shield, which was originally designed to link with more “classic” Arduino boards using a standard shield pin layout.

“Obviously the shield cannot stack onto Trinket but with four wires, the display shield can hook up to a Trinket project well. This is accomplished as both use the I2C or two-wire bus to communicate,” Barela explained in detailed tutorial.

 “As a further demonstration, the Adafruit I2C based DS1307 real-time clock module is used to display the time and date. The display shield’s buttons allow for changing the hour in case of daylight savings time and toggle the backlight.”

Before kicking off the project, Makers will need to download three code libraries (TinyWireM, TinyRTClib, TinyAdafruit_RGBLCDShield) all optimized for Atmel’s ATtiny85 microcontroller (MCU) powering the Trinket. Next up? Modifying the Arduino IDE to work with Trinket by adding the hardware definition file, the avrdude.conf file, changing the ld.exe program (or download the preset Arduino 1.05 from Adafruit).

“Since we’re using I2C for the shield and real time clock, hookup is fairly straightforward,” said Barela.

“Don’t forget, I2C allows you to use multiple devices on two shared pins, perfect for when you don’t have a lot of pins like the Trinket.”

On the code side of things, Barela uses two programs are used to save space. The first, typically runs once (initialization) and sets the battery-backed DS1307 RTC, while the main code displays the clock value and polls the buttons. Meaning, if the up or down buttons are pressed, the value offset is incremented/decremented. This is added to the RTC clock time to form the hour.

“The combination of Trinket and the RGB LCD Shield is a good combination for display and input. There is enough code space to hook a number of sensors for real-time readout,” Barela concluded. “If you believe the shield form factor is not ideal, use of the LCD with the I2C backpack is a good combination. See the tutorial for the Trinket Ultrasonic Rangefinder as an example. If you want a more precise clock, you can swap the DS1307 for a Chronodot, it is code-compatible and ultra-precise!”

Interested in learning more? You can check out Adafruit’s detailed tutorial here.