The PicoCalc manual names the three ways builders break the kit, each behind a warning
A "Three ways to break it" chapter before Phase 1: the bare glass screen that cracks when the mainboard flexes (do the Pico swap with the board out of the case, on a padded surface, and tape the panel's edges with Kapton), the brass screw posts that snap out of the shell when a screw is forced, and the charge control that powering the core board's own USB-C bypasses (forum members measured cells at 4.46 V and 4.74 V after powering the Pico's port). Steps 1 and 2 and the day-to-day section now follow it. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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@@ -11,6 +11,7 @@ a radio in the meantime.
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- [Shopping list](#shopping-list)
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- [Before you start](#before-you-start)
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- [Three ways to break it](#three-ways-to-break-it)
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- [Phase 1 — Build the machine](#phase-1--build-the-machine)
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- [Step 1 — Assemble the PicoCalc](#step-1--assemble-the-picocalc)
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- [Step 2 — Swap the Pico for the Lyra](#step-2--swap-the-pico-for-the-lyra)
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@@ -124,6 +125,62 @@ program built for exactly that.
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---
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## Three ways to break it
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The PicoCalc is a kit, and its forum has a well-worn list of the ways people have damaged
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theirs. Three of them apply directly to this build. Read this section before you open the
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shell.
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> ⚠ **The screen is extremely fragile.** It is a bare glass panel with no frame of its own,
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> and when the case is closed it sits directly against the mainboard. Anything that flexes
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> the mainboard flexes the glass: pushing a board into the Pico socket, prying one out,
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> closing the shell with the screen not sitting square in its opening, or pressing a key
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> while the halves are being screwed together. Forum members have cracked screens doing
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> each of those, and the swap in [Step 2](#step-2--swap-the-pico-for-the-lyra) is the
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> classic one — pressing a new board into the socket with the mainboard still in the case
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> is enough on its own.
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> ([Before replacing the Pico](https://forum.clockworkpi.com/t/before-replacing-the-pico-read-this-to-avoid-cracked-screen/16666),
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> [Avoid breaking your screen](https://forum.clockworkpi.com/t/avoid-breaking-your-screen/18805))
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>
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> What to do instead:
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>
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> - **Never push a board into the socket, or pull one out, with the mainboard in the case.**
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> Unplug the display's ribbon cable (the FPC) from the mainboard, lift the mainboard out,
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> and do the swap on a flat, padded surface — a folded microfibre cloth is ideal. Ease a
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> board out a little at each end in turn, never by levering one end.
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> - **Secure the screen with Kapton tape** along its edges so it cannot shift in the
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> opening while you work and while the case is closed. Kapton is the right tape: thin,
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> it stays put, and it peels off cleanly. Don't use anything that sets hard.
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> - **Before the back goes on, check the screen sits flush and square** in the front half's
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> opening with no pressure on any corner. If the mainboard doesn't sit perfectly flush on
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> the front half, stop and find out why before you add the back.
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> - Handle the panel as little as possible, and keep your fingers off the keyboard while
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> closing the shell.
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> ⚠ **Don't overtighten the screws.** The shell's screw posts are brass inserts moulded
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> into plastic, and forcing a screw snaps the post out of the shell — a repair that needs
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> epoxy and never quite comes back
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> ([Broken screw thread](https://forum.clockworkpi.com/t/broken-screw-thread/20726)).
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> Turn each screw until it just seats, then stop. If a screw won't go in easily, the halves
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> aren't aligned, or something inside is in the way; more force is never the answer.
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> ⚠ **Never power the Lyra through its own USB-C while the batteries are in.** The
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> PicoCalc charges its cells only through the **mainboard's** USB-C port, under the control
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> of its power-management chip (an AXP2101). Power fed in through the core board's USB port
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> — the Pico's originally, the Lyra's now — arrives on the header's system-power pin and
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> bypasses that charge control. Forum members who powered the Pico's port directly measured
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> their cells at **4.46 V and 4.74 V** afterwards, well over the 4.2 V a lithium cell is
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> allowed to reach
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> ([New PicoCalc — battery charging](https://forum.clockworkpi.com/t/new-picocalc-battery-charging/22330)).
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> An overcharged cell is a fire risk, not just a worn one.
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>
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> Nothing in this guide needs the Lyra's USB-C: the serial console, charging and power all
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> use the mainboard's port on the side of the case, and the Wi-Fi dongle uses the 4-pin
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> socket on top of the Lyra. If you ever must plug the Lyra's USB-C into a PC — to
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> reflash it with Luckfox's tools, say — **take both batteries out first.**
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---
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## Phase 1 — Build the machine
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### Step 1 — Assemble the PicoCalc
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@@ -132,9 +189,12 @@ Follow ClockworkPi's own
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[assembly guidelines](https://github.com/clockworkpi/PicoCalc/blob/master/Clockwork_PicoCalc_Assembly_Guidelines.pdf)
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(a PDF in the [PicoCalc repository](https://github.com/clockworkpi/PicoCalc), which also
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has a wiki) to put the kit together: mainboard, screen, keyboard, speakers and shell. Insert your two
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18650 batteries, watching the `+`/`-` marks in the battery compartment. Be careful when you
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tighten the shell's screws near the display — a misaligned screen can crack under the
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screws, and you'll be opening the shell again in the next step regardless.
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18650 batteries, watching the `+`/`-` marks in the battery compartment.
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⚠ Two of the warnings in [Three ways to break it](#three-ways-to-break-it) apply here: tape
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the screen's edges with Kapton before you close the shell and check it sits square, and
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turn the screws only until they seat. You will open the shell again in the next step, so
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there is no reason to make the screws tight now.
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Power it on once with the **stock Pico still in place**. You should see the stock BASIC
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firmware boot on the screen, and the keyboard should respond. This confirms the screen,
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@@ -144,20 +204,28 @@ Power it back off.
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### Step 2 — Swap the Pico for the Lyra
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Remove the back of the shell with the hex key. Lift the Raspberry Pi Pico straight out of
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its socket — **keep it**, you're not damaging or discarding it, just setting it aside.
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Remove the back of the shell with the hex key.
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⚠ **Do the swap with the mainboard out of the case.** This is the step that cracks screens
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(see [Three ways to break it](#three-ways-to-break-it)). Unplug the display's ribbon cable
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from the mainboard, lift the mainboard out, and lay it on a padded surface. Only then ease
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the Raspberry Pi Pico out of its socket, a little at each end in turn — **keep it**, you're
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just setting it aside.
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If your Luckfox Lyra has SPI NAND on board (a "Lyra B"), erase it first — the boot ROM
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otherwise ignores the SD card entirely and boots the on-board flash instead. See
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[Calculinux's hardware requirements page](https://calculinux.org/getting-started/hardware-requirements/)
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for how.
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Seat the Lyra into the same socket the Pico came out of, in the same orientation — its USB-C
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port should line up with the cutout in the back of the shell where the Pico's USB port used
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to be. Press it down fully; a Lyra that isn't fully seated won't boot.
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Seat the Lyra into the same socket the Pico came out of, in the same orientation — its
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USB-C port at the end where the Pico's USB port was, so it lines up with the cutout in the
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back of the shell. Press it down fully with the mainboard still on the padded surface; a
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Lyra that isn't fully seated won't boot. Then reconnect the ribbon cable and set the
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mainboard back into the front half, checking the screen sits square before anything is
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screwed down.
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You should see the Lyra's USB-C port sitting flush in the back-panel cutout, with no rocking
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or gap at either end of the board.
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You should see the Lyra sitting flat on the socket with no gap at either end, and, once
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the mainboard is back in, its USB-C port centred in the back-panel cutout.
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Leave the back off for now. The microSD card goes into the **Lyra's own slot** in
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[Step 4](#step-4--write-the-image-to-the-microsd), and that slot is easier to reach with the
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@@ -699,6 +767,10 @@ mostly useful for isolating a wiring problem.
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## Day-to-day
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**Charging.** Only through the mainboard's USB-C port on the side of the case. ⚠ Never
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through the Lyra's own USB-C at the back — see
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[Three ways to break it](#three-ways-to-break-it).
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**Powering off.** Shut down cleanly rather than pulling the batteries:
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```bash
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