PM_G-1: scrolling boot splash (model name) + transient BPM flash on tempo nudge

The splash doubles as a liveness/pixel-map check (if 'PM-G1 GRID' reads correctly,
the firmware booted and the LED mapping is right). The BPM flash makes X/Y tempo
nudges visible from any view (previously invisible in Grid/Pendulum).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pico-scroll/app.py

@@ -272,6 +272,11 @@ DIGITS = {
     '4': (5, 5, 7, 1, 1), '5': (7, 4, 7, 1, 7), '6': (7, 4, 7, 5, 7), '7': (7, 1, 2, 2, 2),
     '8': (7, 5, 7, 5, 7), '9': (7, 5, 7, 1, 7),
 }
+# 3x5 uppercase letters + marks for the boot splash (scrolls the model name "PM-G1 GRID")
+LETTERS = {
+    'P': (7, 5, 7, 4, 4), 'M': (5, 7, 7, 5, 5), 'G': (7, 4, 5, 5, 7), 'R': (7, 5, 7, 6, 5),
+    'I': (7, 2, 2, 2, 7), 'D': (6, 5, 5, 5, 6), '-': (0, 0, 7, 0, 0), ' ': (0, 0, 0, 0, 0),
+}
 
 # ============================== APP ==============================
 class App:
@@ -301,8 +306,9 @@ class App:
         self.rep = None; self.end = None               # per-track playback flow: rep=cycles, end=stop|next|+/-N goto
         self.continue_on = False; self._advance = False
         self._next_pending = None; self._seam_t = 0
-        self.view = 0                                  # 0 = Grid, 1 = Pendulum, 2 = BPM (button B cycles)
+        self.view = 0                                  # 0 = Grid, 1 = Pendulum, 2 = BPM (button A-hold cycles)
         self._beatflash = 0; self._beatflash_off = 0
+        self._bpm_flash = 0                            # while set, render() briefly shows the BPM view (so X/Y nudges are visible in any view)
         self._beat_ns = 60_000_000_000 // self.bpm
         self._note_buf = bytearray([0x90, 0, 0])
         self._clock_byte = bytes([0xF8]); self._start_byte = bytes([0xFA]); self._stop_byte = bytes([0xFC])
@@ -531,6 +537,7 @@ class App:
         if v != self.bpm:
             self.bpm = v; self._beat_ns = 60_000_000_000 // v
             self._rebuild_dur_all(); self.dirty = True
+            self._bpm_flash = time.monotonic() + 0.7      # flash the tempo so the nudge is visible even in Grid/Pendulum
             self._sync_broadcast("bpm=%d" % v)
     def goto(self, i):
         was = self.running
@@ -708,10 +715,35 @@ class App:
         if lvl == 1: return max(8, BRIGHTNESS // 4)         # normal
         if lvl == 3: return max(3, BRIGHTNESS // 16)        # ghost
         return 0
+    def _splash(self, text):
+        # Scroll text across the matrix once at boot, right-to-left, as a 3x5 font on rows 1..5.
+        # Doubles as a liveness + pixel-map check: if "PM-G1 GRID" reads correctly, the firmware
+        # booted and the LED mapping is right.
+        cols = []
+        for ch in text:
+            g = DIGITS.get(ch) or LETTERS.get(ch.upper()) or LETTERS.get(' ')
+            for cx in range(3):
+                c = 0
+                for ry in range(5):
+                    if g[ry] & (1 << (2 - cx)): c |= (1 << ry)
+                cols.append(c)
+            cols.append(0)                              # 1px gap between glyphs
+        n = len(cols); m = self.mtx; off = -16
+        while off < n:
+            m.clear()
+            for x in range(17):
+                ci = x + off
+                if 0 <= ci < n:
+                    c = cols[ci]
+                    for ry in range(5):
+                        if c & (1 << ry): m.set(x, ry + 1, BRIGHTNESS)
+            m.show(); time.sleep(0.05); off += 1
     def render(self):
         self.mtx.clear()
-        if self.view == 2: self._render_bpm()
+        v = self.view
-        elif self.view == 1: self._render_pendulum()
+        if v != 2 and self._bpm_flash and time.monotonic() < self._bpm_flash: v = 2   # transient tempo readout
+        if v == 2: self._render_bpm()
+        elif v == 1: self._render_pendulum()
         else: self._render_grid()
         self.mtx.show()
     def _render_grid(self):
@@ -927,6 +959,8 @@ class App:
         boot = time.monotonic()
         try: os.stat("/trial"); committed = False
         except OSError: committed = True
+        try: self._splash("PM-G1 GRID")               # boot banner (scrolls once); wrapped so a splash bug never blocks the app
+        except Exception: pass
         next_frame = 0.0
         while True:
             try:
@@ -940,6 +974,9 @@ class App:
                     self._sync_broadcast_full()
                 if self.running and tnow >= next_frame:      # keep pendulum/playhead moving even with no input
                     self.dirty = True; next_frame = tnow + 0.04
+                if self._bpm_flash:                          # keep rendering through the tempo flash, then one frame to revert
+                    if tnow >= self._bpm_flash: self._bpm_flash = 0
+                    self.dirty = True
                 if self.dirty:
                     self.dirty = False; self.render()
                 time.sleep(0.0005)