The apps and the firmware ship together this time. Update both.
Six times the battery, with the radio still on
Reading with your phone connected drew 44 milliamps. It now draws 7. On
the X3's 650 mAh battery that is about 15 hours of reading before, and
about 90 hours now.
The stock Arduino system libraries for this chip ship with power
management compiled out, and no application code can turn it on. So we
rebuilt them. Three steps got us there, and each one was measured on the
bench.
| Step | Reading, phone connected |
|---|---|
| Stock libraries (0.6.6 and earlier) | 44 mA |
| Radio modem sleep | 23 mA |
| Processor frequency scaling, 40 MHz floor | 16 mA |
| Light sleep with Bluetooth still alive | 7 mA |
The radio used to cost about 25 mA on its own, more than half the total,
because its controller never slept between connection events. It now costs
about 3. You keep notifications and position sync while you read, which
used to cost you the radio entirely.
The device sleeps only while your phone is connected, never while
charging, never during a transfer, and never with a computer attached. A
phone cannot open a new connection into a sleeping device, so while your
phone is away the device wakes for a few seconds at a time to let it back
in.
Measured on the X3, which has a battery gauge. The X4 has none, so it has
no measured figure, but it runs the same chip and radio.
More room to work
The chip has 400 KB of memory and no virtual memory to fall back on.
| Where | 0.6.6 | 0.7.0 |
|---|---|---|
| Reading, connected, free | 14.3 KB | 46-48 KB |
| Reading, largest single block | 7.1 KB | 36.9 KB |
| Home screen, connected, free | 25.7 KB | 58.8 KB |
This is why big books stopped rendering blank pages, and why the reader no
longer drops your phone connection to find room. A Wi-Fi transfer also
hands the radio back to Bluetooth without a reboot now.
Faster
The bookshelf opens at once. The device used to open every book on the
card to draw the shelf. On a full shelf, pressing BOOKS from inside a book
took about 3.5 seconds. The device now keeps a small index of what it
found, so the same press takes about 0.8 seconds. Measured on an X4 with
24 books.
The index looks after itself. It is rebuilt if it is missing or damaged,
it survives a card that fills up mid-write, and a damaged book cannot
spoil it. The first press after this update is slow once, while the index
is built.
Page turns on the X4 are 21 percent quicker, at 594 ms against 752.
The chapter menu opens at once, and lists your book's real chapters.
Sleep
Your device naps instead of dying. After five minutes of quiet it
naps. The screen keeps showing your priorities, the phone link stays up,
and a short press of the power button brings your screen back. After an
hour of quiet it turns off, and never while charging. The off screen is
the nap screen inverted, so you can tell them apart across the room.
Both times are yours. Settings > Sleep sets the nap between two and
thirty minutes, and the off between fifteen minutes and four hours. Either
can be turned off.
While it naps, the screen follows your phone. A new priority, a
workout, or a new event redraws it quietly.
Reading
Hyphenation. Books rebuilt on the phone break lines properly.
Footnotes. On a page with a mark, the menu offers the note. One press
jumps there and the BOOKS key brings you back.
Look up a word. Menu > Look up moves a box word by word. Press GO for
the dictionary. Copy the dictionary to the device first, from Settings >
Reading on the phone. It is English and 8.5 MB, and the device needs Wi-Fi
to take it.
Highlight a paragraph. Menu > Highlight marks the paragraph you are
on. A connected phone gets each highlight as you make it.
Choose whether the radio stays on while you read. Menu > Radio while
reading offers Auto, Always and Never. Auto is the default. It keeps the
radio on unless the battery is at or below 20 percent.
The end of a book. A Finished screen with the time you spent, Mark
finished, and the next book waiting. Finished books move to their own
shelf, on the device and on the phone.
A footer you choose. It shows nothing, the page, the percent, or the
time left in the chapter.
These reading features need a prepared book. Hyphenation, footnotes,
highlights and word lookup all come from a book your phone built. A book
copied straight onto the card still reads, but it does not get them. Sync
the book again and it gains them.
Sync
Syncing happens in place. The screen no longer jumps to a transfer
page. A bar takes over the bottom of the screen while a sync runs, and the
device comes back to the same spot afterwards.
A book the card cannot read is skipped. It is left off both listings
and a download of it is refused, so a damaged file can no longer stall a
sync.
Deleting stays done. A book deleted on the device does not come back
on the next sync.
Wi-Fi
Test a network from the device. Each saved network now has a Test this
network row. The device joins, gets an address, waits for your phone to
knock, and comes back with one sentence telling you what happened.
Forget a place that blocked you. Some networks stop the phone and the
device from seeing each other. The apps remember such a place and go
straight to the device's hotspot there for twelve hours. You can clear
that memory from the app, under Device Wi-Fi.
Stability
A watchdog catches a stuck loop. The busiest task got more room. A radio
that goes quiet restarts itself. If the device ever freezes it records
where it was stuck, into memory the reset button does not clear, and
writes a report to the card on the next start.
Display, on the X4
Two panel faults fixed: a sleep screen that flashed and vanished, and a
screen change that could leave the previous screen mixed into the new one
after a fast key press.
Known and not fixed
Deleting a book from the device leaves its cover file behind on the card.
Harmless litter.
A book the device cannot read still appears in the device's own list and
says "Couldn't open this book" when you open it. The phone hides it, so
the two disagree. It fails safely. There is still no way to delete such a
file from the device.
A book taken from the Press keeps the file name of its source, which can
be ugly. Cosmetic only.
Install
Browser, easiest. Open https://www.flowe.ink/flash in Chrome or Edge,
plug in USB-C, and press Update Flowe. It keeps your pairing and your
books.
microSD card. Download flowe-firmware.zip, copy update.bin to the root
of the card, put the card back, then hold the left side button and power
together until the update screen appears.
One file works on both the Xteink X3 and X4. The firmware detects your
device.
Apps
Update both in the same week. The apps and this firmware share a page
layout, and a book built by the new app hides its last lines on older
firmware.