Add audiobusio examples and fix simple test frequency

This also uses newer pin auto-init.

Author: tannewt

examples/pioasm_i2sout.py

@@ -0,0 +1,71 @@
+# SPDX-FileCopyrightText: 2021 Scott Shawcroft, written for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+
+import audiocore
+import audiopwmio
+import board
+import digitalio
+import array
+import time
+import math
+import rp2pio
+import adafruit_pioasm
+
+trigger = digitalio.DigitalInOut(board.D4)
+trigger.switch_to_output(True)
+
+# Generate one period of sine wav.
+length = 8000 // 440
+
+# signed 16 bit
+s16 = array.array("h", [0] * length)
+for i in range(length):
+    s16[i] = int(math.sin(math.pi * 2 * i / length) * (2 ** 15))
+    print(s16[i])
+
+program = """
+.program i2s_with_hold
+.side_set 2
+
+; Load the next set of samples
+                    ;        /--- LRCLK
+                    ;        |/-- BCLK
+                    ;        ||
+    pull noblock      side 0b01 ; Loads OSR with the next FIFO value or X
+    mov x osr         side 0b01 ; Save the new value in case we need it again
+
+    set y 14          side 0b01
+bitloop1:
+    out pins 1        side 0b10 [2]
+    jmp y-- bitloop1  side 0b11 [2]
+    out pins 1        side 0b10 [2]
+
+    set y 14          side 0b11 [2]
+bitloop0:
+    out pins 1        side 0b00 [2]
+    jmp y-- bitloop0  side 0b01 [2]
+    out pins 1        side 0b00 [2]
+"""
+
+assembled = adafruit_pioasm.assemble(program)
+
+dac = rp2pio.StateMachine(
+    assembled,
+    frequency=800000 * 6,
+    first_out_pin=board.D12,
+    first_sideset_pin=board.D10,
+    sideset_pin_count=2,
+    auto_pull=False,
+    out_shift_right=False,
+    pull_threshold=32,
+    wait_for_txstall=False,
+)
+
+trigger.value = False
+dac.write(s16)
+time.sleep(1)
+dac.stop()
+trigger.value = True
+
+print("done")

examples/pioasm_neopixel.py

@@ -28,8 +28,6 @@
 sm = rp2pio.StateMachine(
     assembled,
     frequency=800000 * 6,  # 800khz * 6 clocks per bit
-    init=adafruit_pioasm.assemble("set pindirs 1"),
-    first_set_pin=board.D12,
     first_sideset_pin=board.D12,
     auto_pull=True,
     out_shift_right=False,

examples/pioasm_pdm.py

@@ -0,0 +1,64 @@
+# SPDX-FileCopyrightText: 2021 Scott Shawcroft, written for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+
+import board
+import digitalio
+import array
+import time
+import rp2pio
+import adafruit_pioasm
+
+trigger = digitalio.DigitalInOut(board.D4)
+trigger.switch_to_output(True)
+
+# signed 16 bit
+s16 = array.array("H", [0] * 10000)
+
+# Capturing on the rising edge is the left PDM channel. To do right, swap the
+# side set values.
+#
+# push iffull means it'll push every 32 bits and noop otherwise. noblock causes
+# data to be dropped instead of stopping the clock. This allows the mic to warm
+# up before the readinto.
+program = """
+.program pdmin
+.side_set 1
+    in pins 1            side 0b1
+    push iffull noblock  side 0b0
+"""
+
+assembled = adafruit_pioasm.assemble(program)
+
+sm = rp2pio.StateMachine(
+    assembled,
+    frequency=24000 * 2 * 32,
+    first_in_pin=board.D12,
+    first_sideset_pin=board.D11,
+    auto_push=False,
+    in_shift_right=True,
+    push_threshold=32,
+)
+
+# Give the mic a bit of time to warm up (thanks to our noblock.)
+time.sleep(0.1)
+
+print("starting read")
+trigger.value = False
+# Clear the fifo to ignore old values and reset rxstall.
+sm.clear_rxfifo()
+sm.readinto(s16)
+# Capture rxstall quickly so we can hopefully tell if we dropped data. (We
+# definitely will at some point after readinto is done.)
+stalled = sm.rxstall
+trigger.value = True
+print("read done")
+
+if stalled:
+    print("missed samples")
+
+# These are raw one bit samples. audiobusio.PDMIn does an extra filtering step.
+# for v in s16:
+#     print(v)
+
+print("done")

examples/pioasm_simpletest.py

@@ -9,17 +9,16 @@
 
 squarewave = """
 .program squarewave
-    set pins 1 [1]  ; Drive pin high and then delay for one cycle
+    set pins 1      ; Drive pin high and then delay for one cycle
     set pins 0      ; Drive pin low
 """
 
 assembled = adafruit_pioasm.assemble(squarewave)
 
 sm = rp2pio.StateMachine(
     assembled,
-    frequency=80,
-    init=adafruit_pioasm.assemble("set pindirs 1"),
-    first_set_pin=board.LED,
+    frequency=1000 * 2,
+    first_set_pin=board.D13,
 )
 print("real frequency", sm.frequency)