it is an LCD-Memory screen

LTPS tech made by JDI

http://www.j-display.com/product/pdf/LPM...

Garmin uses it on the Forerunner 920XT

in HOLD mode the screen still needs power, but a mere 0.13mW

for comparison in full refresh it takes 4.292mW

the battery holds 0.57Wh so it would hold the screen content for ~4384 hours or ~26 weeks

even at full refresh rate it would be running for ~5.5 days

but that is the display only, the MCU has to wake up to refresh the screen, the sensors need to be polled and the radio takes some power too.

But the screen itself is pretty much the lowest power option they could take :)

so there is no additional RAM on the PCB? just the 256k of the MCU?

that is on one hand a bummer and on the other hand a great thing

the FPGA is possibly used for motion detection stuff and the display to keep the MCU asleep while processing the data for said devices.

there is a Cypress touch screen controller and one from Atmel?