A Kickstarter project is pitching a HAT add-on for the Raspberry Pi that provides a 2.7-inch E-paper display, as well as a battery backed real time clock.
For educators, one of the coolest things about the Raspberry Pi is the HDMI port, which let you easily plug in to a monitor. But for embedded gizmos, a more modest display is often more suitable. It doesn’t get much more modest than Percheron Electronics’s E-Paper HAT Display, a Raspberry Pi add-on board that drives a 2.7-inch, 264 x 176-pixel E-paper display from Pervasive Displays.
E-Paper HAT Display on a Raspberry Pi
(click image to enlarge)
Percheron is just shy of its $15,241 Kickstarter goal and has already sold out two early bird rounds. The E-Paper HAT Display is currently available for a low of 39 UK Pounds (about $57) or 69 Pounds ($101) for a two-pack. Shipments are due in September.
The board complies with the Raspberry Pi Foundation’s HAT (Hardware Attached on Top) stacking add-on board standard, which we recently saw in Pimeroni’s Explorer HAT IoT and motor control add-on. The HAT support extends to matching the “device tree configuration of the required GPIO pins by the HAT EEPROM,” says Percheron. One of the main benefits of using the HAT format is that it’s more compact and portable, and you avoid cable tangle.
Rear view of E-Paper HAT Display
(click image to enlarge)
The E-Paper HAT Display supports a wide variety of applications including a desk or wall clock, a weather station, or a Twitter feed display. The monochrome E-Paper display uses a fraction of the power of an LCD display, but cannot support video or fast animation. One advantage of the display is that the last message sent remains on the screen even if the power goes down, says Percheon.
The device supports 1.44-inch and 2-inch E-paper displays from Pervasive Displays in addition to the 2.7-inch display that is built into the HAT. The displays are rated for 0 to 50°C operating temperatures.
The PCB also includes Maxim Integrated’s DS3231 real time clock (RTC) with CR1220 lithium coin cell battery backup. The DS3231 is claimed to be accurate within three minutes per year. The RTC can generate an interrupt/alarm signal, as well as a 32KHz clock signal that can be connected with GPIO pins using solder pad links.
Pervasive Displays provides firmware via its open source RePaper.org project, which releases sample programs under Apache 2.0 license and publishes full documentation. RePaper also has starter kits for the Raspberry Pi, as well as BeagleBone, Arduino, and LaunchPad.
The firmware, which can be found at the RePaper GitHub repository, includes a low level C driver that interfaces to numerous hackable Python demo programs. For example, you can draw new images to the panel or partially redraw sections of the display using the Python Imaging Library (Pillow). RePaper offers text for a variety of fonts in various sizes.
Percheron Electronics’s lead developer is UK Raspberry Pi hacker Neil Matthews. He says he can be frequently found at Cambridge Raspberry Jams.
The E-Paper HAT Display from Percheron Electronics is available through May 10 on Kickstarter starting at 39 Pounds (about $57), or 69 Pounds ($101) for a two-pack and 180 Pounds ($264) for a five-pack. Shipments are due in August or September depending on the package. More information may be found at the E-Paper HAT Display Kickstarter page.