Krok User Guide

What you need

• A Krok (a LilyGo T5 E-Paper S3 Pro with Krok installed), or your own T5 E-Paper S3 Pro to install Krok on.
• A microSD card, FAT32, 4 to 32 GB. Maps, tracks and settings live on it.
• A USB-C cable that carries data, not only charge.
• A 2.4 GHz Wi-Fi network with a password (WPA or WPA2 Personal). Krok cannot use 5 GHz networks, hotel or café sign-in pages, or company networks that ask for a user name. A phone hotspot works.

Charging

Plug USB-C into a charger or a computer. A bolt appears in the battery icon at the top right while it charges. A full charge lasts several days of normal hiking use with the screen mostly still; it lasts much less if the GPS is set to Often or the front light is on.

Hold Krok with the screen facing you.

The microSD slot is on the right edge under PWR.

The screen is also a touch screen: tap a row to open it. A row turns black for an instant when your tap is taken; the new page follows.

Lock. Hold BOOT for a little over a second (1.2 s). A small padlock appears at the top. While locked, touch and the function button do nothing, so Krok can ride in a pocket. Hold BOOT again to unlock, or hold BOOT while waking from sleep to unlock right away.

Skip this section if your Krok came with the software installed.

1. Open gokrok.com/flash in Chrome or Edge on a computer. (Safari and Firefox cannot talk to USB devices.)
2. Connect the board with the USB-C data cable.
3. Click Install, choose the port that appears, and confirm. Choose Erase the first time. The install takes about two minutes. Do not unplug the board.
4. If no port appears: hold BOOT, press and release RST, then release BOOT. The board is now waiting for an install; click Install again. After the install, press RST once.
5. The page then offers to connect Wi-Fi: pick your network and type its password on the computer. Krok saves it.
6. Next, choose your maps on the page: click the squares around where you hike, or drop a GPX file of a planned route and the page selects the squares it crosses. Click Send to Krok. Krok downloads them by itself over Wi-Fi.

Not yet tried on a production unit: steps 5 and 6.

The first time Krok starts with no maps on its card it opens Setup. Every row is optional, and BOOT leaves Setup at any time. You can open it again later from Settings > About > Setup.

About map squares. Maps come in squares of half a degree, about 55 km north to south. Each is one file of up to 16 MB. Download the squares you need before you leave signal; the map itself works with no connection at all. Map near me sends the server only the name of the square, never your position.

If a map says "Queued - try later", that square had not been built yet. The server is building it; try again in an hour.

Home lists Map, Trails, Utils, Library, File transfer and Settings. With the radio on, Group appears after Library.

The top line on every page shows the time on the left and, on the right, the battery, then the satellite count, a padlock while locked, a Wi-Fi mark while connected, and LR while the radio is on.

Open Map. Your position is a circle when you stand still and an arrow when you walk, pointing the way you move. North is always up.

• Zoom: + and − at the upper right. The square under − puts you back in the middle of the screen.
• Look around: drag the map. While your finger moves you see a dot grid; lift it and the map is drawn at the new place. The function button brings you back to your position.
• Where am I now: a short press of the function button. Krok updates your position quickly for the next two minutes.
• Leave the map: short BOOT.

No position yet. Until the GPS has a position, Map shows the sky: the satellites heard, their strength and how long it has been looking. The first position outdoors can take a few minutes, longer under trees or in a canyon. It is faster after that.

How Krok saves battery. You do not choose a mode. After two minutes without touching it, Krok checks your position every 30 seconds instead of every second; while you walk with it unlocked, it stays quick. Left still for 15 minutes, it shows Sleep at the top and sleeps with the map on the screen. Press BOOT to wake it.

Settings > GPS changes this: Often updates every second (uses more battery), Auto is the default, Saver checks every 5 minutes.

On the map, tap Start at the bottom. The bar shows the time and the distance; with a trail open it also shows the elevation. Tap the two bars on the left to Pause, then Resume or Finish. Buttons on the bar answer touch only, so a pocket press cannot end a walk.

Finish shows distance, climb, time and points. Save keeps the walk; Delete removes it. Walks are GPX files in /tracks on the card.

If you stand still for 20 minutes while recording, Krok pauses the walk for you. If the battery reaches 3 %, it finishes and saves the walk.

Trails lists the GPX files in /tracks: your walks and any route you copy there. Pick one to see its distance, climb and time, then Show on map to draw it as a dashed line. Profile shows its elevation; drag along it to read any point. While a trail is shown, the first row of Trails is Hide.

Library opens the Survival guide and any books in /books (.txt or .md). Upload those from File transfer; each book can be up to 4 MB. The guide starts with emergencies. Tap the magnifier to search it.

In a page: tap the right third to turn forward, the left third to go back, the middle for text size. The function button also turns forward. BOOT leaves. Krok remembers your place.

The guide is general information, not a substitute for training or for calling for help. In an emergency, call your local emergency number or use a satellite messenger if you carry one.

Clock, Temperature (the battery's temperature over 24 hours, not the air), List (a packing list you can tick off and edit, also editable from File transfer) and Legend (what every map symbol means).

File transfer puts Krok on Wi-Fi so a browser can manage its card: download maps, copy GPX routes and books (.txt or .md) in and walks out, delete maps, tracks and books, and edit the list.

• Join: Krok joins your Wi-Fi. The screen shows an address; open it in a browser on the same network.
• Hotspot: Krok makes its own network. Its name, password and a QR code are on the screen.

A short press of BOOT closes File transfer.

Settings > About > Check for updates joins your saved Wi-Fi, then:

• installs a newer survival guide (a few MB, kept on the card);
• offers a newer Krok version. It installs into a spare slot, checks the download's signature first, and restarts. If the new version does not start properly, Krok goes back to the previous one by itself.

Krok will not update while a walk is recording or the battery is below 30 % off the charger.

Offline: download firmware.bin and firmware.sig from the releases page, copy them onto the card as /update/fw.bin and /update/fw.sig, then Settings > About > Install from card.

Without a licence Krok runs in trial: everything works, for as long as you like, with one map square. Uploaded tracks, recording, the guide, the radio and the tools are not limited.

To unlock more maps, open Settings > About > Licence and scan the QR code with your phone, or follow the link on the install page while the board is plugged in. After payment the licence arrives the next time Krok checks for updates; it is also in your receipt e-mail as license.key, which you can copy to /config/ on the card.

The licence belongs to your board and is checked on the board itself. Krok never needs the internet to keep it.

Settings > Turn off draws the map with Off at the top and cuts the battery. Press PWR to turn on. Krok will not turn off while charging, while a walk is recording or paused, or during a file transfer; the row says why.

Sleep (section 6) costs very little and keeps your walk; turning off costs nothing and restarts Krok fresh.

• Krok is a navigation aid. Carry a paper map and a compass where it matters, and know how to use them. GPS can be wrong or absent.
• Map data © OpenStreetMap contributors, available under the Open Database Licence. Elevation from USGS 3DEP and Copernicus DEM.
• Krok includes epdiy (LGPL-3.0), the Arduino-ESP32 core (LGPL-2.1), Monocypher (CC0) and QRCode (MIT). The releases page has their notices and the files needed to relink Krok with a modified epdiy or core.
• Your position is not sent anywhere. Walks stay on your card.
• Hardware. The T5 E-Paper S3 Pro is made by LilyGo. A pre-flashed Krok is that unmodified board, bought, checked, loaded with software and maps, and forwarded to you as a service. Hardware warranty and certification are LilyGo's.