Add script for bring-up on Tiny Tapeout demo board

bring-up/tt_um_tiny_shader_mole99/__init__.py

@@ -0,0 +1 @@
+from .tt_um_tiny_shader_mole99 import main as run

bring-up/tt_um_tiny_shader_mole99/pio_spi.py

@@ -0,0 +1,59 @@
+# SPI using PIO, which is handy because you can use any pins.
+
+import rp2
+from machine import Pin
+
+@rp2.asm_pio(out_shiftdir=0, autopull=True, pull_thresh=8, autopush=True, push_thresh=8, sideset_init=(rp2.PIO.OUT_LOW,), out_init=rp2.PIO.OUT_LOW)
+def spi_cpha0():
+    out(pins, 1)             .side(0x0)
+    in_(pins, 1)             .side(0x1)
+
+@rp2.asm_pio(out_shiftdir=0, autopull=True, pull_thresh=8, autopush=True, push_thresh=8, sideset_init=(rp2.PIO.OUT_LOW,), out_init=rp2.PIO.OUT_LOW)
+def spi_cpha1():
+    pull(ifempty)            .side(0x0)
+    out(pins, 1)             .side(0x1).delay(1)
+    in_(pins, 1)             .side(0x0)
+
+class PIOSPI:
+
+    def __init__(self, sm_id, pin_mosi, pin_miso, pin_sck, cpha=False, cpol=False, freq=1000000):
+        assert(not(cpol))
+        if not cpha:
+            self._sm = rp2.StateMachine(sm_id, spi_cpha0, freq=2*freq, sideset_base=Pin(pin_sck), out_base=Pin(pin_mosi), in_base=Pin(pin_miso))
+        else:
+            self._sm = rp2.StateMachine(sm_id, spi_cpha1, freq=4*freq, sideset_base=Pin(pin_sck), out_base=Pin(pin_mosi), in_base=Pin(pin_miso))
+        self._sm.active(1)
+
+    @micropython.native
+    def write(self, wdata):
+        first = True
+        for b in wdata:
+            self._sm.put(b, 24)
+            if not first:
+                self._sm.get()
+            else:
+                first = False
+        self._sm.get()
+
+    def read(self, n):
+        return self.write_read_blocking([0,]*n)
+
+    @micropython.native
+    def readinto(self, rdata):
+        self._sm.put(0)
+        for i in range(len(rdata)-1):
+            self._sm.put(0)
+            rdata[i] = self._sm.get()
+        rdata[-1] = self._sm.get()
+
+    @micropython.native
+    def write_read_blocking(self, wdata):
+        rdata = bytearray(len(wdata))
+        i = -1
+        for b in wdata:
+            self._sm.put(b, 24)
+            if i >= 0:
+                rdata[i] = self._sm.get()
+            i += 1
+        rdata[i] = self._sm.get()
+        return rdata