Pocket Pad

The display driver includes a command to invert the display and I have included a facility to choose an inverted display in the Settings app. I am still undecided as to which setting is more readable, however after implementing the analog clock app shown below, I noticed some ghosting of the second hand with black on a white background which is not visible in the inverted display.

I had thought that having the clock display update every second might reduce battery life, however so far this has not been noticeable. The time to update the display for the second hand is 40ms so this represents only a 4% increase in CPU usage which is the only increase in power consumption. Unlike E-paper displays which take a lot of power to update but none when quiescent, the power used by these reflective displays is more or less constant.

Video shows creation and execution of the traditional Hello, World program. Executed first from Editor App and then as an App in its own right. Typing is painful as usually I use thumbs with this keyboard but to keep it in focus it had to be flat on a table. 

Monitor App

The Pocket Pad does not have any spare pins for peripherals, however, it does have bluetooth which can be used to connect to external devices and sensors.

I had already made a Seeed Studio XIAO NRF52840 based environment monitoring station with BMP280 (Atmospheric Pressure) and SCD41 (CO2, Humidity, Temp) sensors. This includes readings from its sensors in the bluetooth advertising broadcast message. The Pocket Pad Monitor App receives these sensor advertisements and can then connect to a selected device using its BLE UART service to access trend data stored on the device. The picture below shows the sensor device and Pocket Pad accessing the record of the last six days atmospheric pressure readings.

The observant reader will notice some slight discrepancies in readings - these are caused by a loss of precision in the readings included in the Bluetooth advertisement messages - and some inconsistent treatment of rounding in my software :-(

Further details of the environment monitor can be found in the Github repository here.