Drive the UI from your desk

Everything the keyboard can do, a command can do, and everything on the screen can be looked at remotely. That makes the Cardputer testable like a web page: act, look, repeat.

Keys

key up|down|left|right|select|back|home|del|tab|space
key a        # any single character: it is typed

Two things to know before you use them:

1. A name key does not know is select. key sleect presses Enter. A single character is typed as that character; anything else that is not a known name is treated as Enter. Check what you type.
2. A key that wakes a dark screen only wakes it. The device's power policy swallows the key press that turns the screen back on, as it does for the real keyboard: the first key after the screen went off does nothing else. Send key back (harmless) first, or keep the screen on with the normal and short commands below.

Fn combinations, modifiers and the compose key have no command: the arrows are key up|down|left|right, and key back is the back key (` on the device). Text is typed one character at a time.

Look before you press

Take a screenshot before any key that deletes, renames or installs. A blind sequence of key commands goes wrong the moment the screen is not where you think it is, and the screen is often not where you think it is: a Toast, a dialog that has not closed, a different App. A sequence that was meant to open a note once renamed real data instead.

scripts/rdbg.py key home          # to the Launcher
scripts/rdbg.py screenshot a.png  # look: is it the Launcher?
scripts/rdbg.py key down
scripts/rdbg.py key select
scripts/rdbg.py screenshot b.png  # look again before the next destructive step

• Prefer reading a state to assuming it: info, ls <folder>, cat <file>, irc dump, gnss status, lora status, wifi status, update status.
• Test on a scratch folder on the card, not on your real files.
• For anything that deletes (rm, a delete dialog), ls first and ls after.

Keep the screen on, and make timeouts short

short     # screen dims after 5 s, turns off after 10 s: to test the screen policy
normal    # back to 30 s and 60 s
burst     # five Toasts at once: to test notifications
sound on | sound off

Fake the inputs

Each of these puts something in, without the outside world:

Test the update path

An update that goes wrong is the case you most want to rehearse, and a Debug Build can make it go wrong on purpose:

update status                       # what the device runs, what failed here before, the daily check, heap
update check | update list          # look at the server: the latest release, or the last ten
update pretend v0.9.0               # take the running version to be v0.9.0: the latest release now counts as "new"
update damage cut 50000             # the next download is cut after 50000 bytes
update damage flip 100000           # ...or has the byte at offset 100000 damaged
update install v0.11.0 force        # try the install
update probe git.twis.la            # is that server's certificate accepted? (the two ISRG roots only)
update daily                        # forget today's daily check: it runs again at the next tick
update pretend off                  # back to the real version

• force is needed on a Debug Build. A plain update install <tag> answers Debug Build: update from the PC, because installing a release would replace the console with a build that has none. force is accepted only on a Debug Build, and only from the console.
• A damaged download must be refused cleanly: the Update Service checks the signature after the first 160 bytes and the image hash at the end, so a cut or a flipped byte must end in a refusal with nothing switched. Check info afterwards: both slots, and update: confirmed.
• An undamaged force install really installs the release, into the other slot. The Debug Build stays where it was until the next update overwrites it, and a Rollback returns to it, but think before you do it.
• The server is read by the device itself, with Wi-Fi up; the download is one TLS connection, about 52 KB of heap at its peak, so IRC steps aside (see the memory limit). status: heap in the stream shows it happen.

For crashes during Probation, see Crashes and Safe Mode.

Test a network change without losing the console

The Debug Console runs over the Wi-Fi you are about to change, which is the usual way to lock yourself out. A trial IP setting takes care of it:

wifi ip MyNet 10.39.39.50/24 10.39.39.1 try 60     # use this address for 60 s...
wifi ip keep                                       # ...and keep it, if you could still reach the device

If you do not send wifi ip keep in time, the device goes back to the previous setting by itself, and the console comes back with it. (A Debug Build command: try is not in release builds.)

Measure

info       # firmware, uptime, last start reason, heap now/lowest/largest block, chip temperature, Wi-Fi, SD faults, both app slots
tasks      # each task over the next second: state, priority, least free stack, CPU share; each core's load; main-loop passes
net        # bytes each network service has read and written since start

tasks takes a second to answer. A low number in the stack column is a risk (the System App shows it in the warning colour under 512 bytes). loop spin on|off (Debug Build) makes the main loop spin without resting, to compare load and radio noise. And the status: heap line every 10 seconds in the stream is the cheapest memory trace there is: watch it while you do the thing you suspect.

task             st   pri  stack   cpu% core
loopTask         R      1   1828    1.3 1
wifi             B     23   4072    0.7 0
debug            B      1   3088    0.5 -1
...
load: core 0 2 %, core 1 1 %
loop: 50 passes in the last second, chip 35.3 C

The System App shows the same, live, on the device.

Radio experiments

lora preset <name> and lora custom <MHz> <BW kHz> <SF> <CR> <sync hex> [preamble] change what the receiver listens to (receive only: the radio never transmits), lora sweep on [from] [to] [step] takes a survey, and lora noise test [gnss|quiet] (Debug Build) runs a Sweep under one changed condition at a time, with Wi-Fi off for a moment, to find what raises the noise floor. lora probe finds the radio and reports its chip, oscillator, antenna switch, interrupt line and noise floor. Details in the command reference.