Initial import - audio output

.gitignore

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+/build/

.gitmodules

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+[submodule "src/vendor/pico-stdio-usb-simple"]
+	path = src/vendor/pico-stdio-usb-simple
+	url = https://github.com/mordae/pico-stdio-usb-simple

etc/regmap.py

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+from dataclasses import dataclass
+from fnmatch import fnmatch
+from sys import argv
+
+from lxml.etree import XML
+
+# List of <peri>.<register> patterns to mark as unsafe.
+UNSAFE: list[str] = [
+    "SIO.SPINLOCK[0-9]*",
+    "ADC.FIFO",
+    "SSI.*CR",
+    "SIO.DIV_QUOTIENT",
+    "SIO.DIV_REMAINDER",
+    "SIO.FIFO_RD",
+    "M0PLUS.SYST_CSR",
+    "I2C*.IC_CLR*",
+    "TIMER.TIME[HL]R",
+    "PIO*.RXF*",
+    "PPB.*",
+    "XIP.*",
+]
+
+
+def is_unsafe(peri: str, reg: str) -> bool:
+    for pattern in UNSAFE:
+        if fnmatch(f"{peri}.{reg}", pattern):
+            return True
+
+    return False
+
+
+with open(argv[1], "rb") as fp:
+    xml = XML(fp.read())
+
+
+@dataclass
+class Register:
+    name: str
+    offset: int
+    reset: int
+    read: bool
+    write: bool
+
+
+@dataclass
+class Peripheral:
+    name: str
+    base: int
+    regs: list[Register]
+
+
+peripherals: dict[str, Peripheral] = {}
+
+for peri in xml.cssselect("peripheral"):
+    if "derivedFrom" in peri.attrib:
+        orig = peripherals[peri.attrib["derivedFrom"]]
+        names = peri.cssselect("peripheral > name")
+        assert len(names) == 1
+
+        peripheral = Peripheral(name=names[0].text, base=orig.base, regs=orig.regs)
+        continue
+
+    names = peri.cssselect("peripheral > name")
+    assert len(names) == 1
+
+    bases = peri.cssselect("peripheral > baseAddress")
+    assert len(bases) == 1
+
+    base = int(bases[0].text, 16)
+    peripheral = Peripheral(name=names[0].text, base=base, regs=[])
+
+    for reg in peri.cssselect("peripheral > registers > register"):
+        names = reg.cssselect("register > name")
+        assert len(names) == 1
+
+        offsets = reg.cssselect("register > addressOffset")
+        assert len(offsets) == 1
+
+        resets = reg.cssselect("register > resetValue")
+        assert len(resets) == 1
+
+        accesses = reg.cssselect("access")
+        assert len(accesses) > 0
+
+        write = read = False
+
+        for access in accesses:
+            match access.text:
+                case "read-only":
+                    read = True
+
+                case "read-write":
+                    write = read = True
+
+                case "write-only":
+                    write = True
+
+                case mode:
+                    assert False, f"unknown access mode {mode!r}"
+
+        offset = int(offsets[0].text, 16)
+        reset = int(resets[0].text, 16)
+        register = Register(
+            name=names[0].text,
+            offset=offset,
+            reset=reset,
+            write=write,
+            read=read,
+        )
+        peripheral.regs.append(register)
+
+    peripherals[peripheral.name] = peripheral
+
+print(
+    """
+#include "regmap.h"
+
+struct reg_info regmap[] = {
+""".strip()
+)
+
+for peripheral in peripherals.values():
+    for register in peripheral.regs:
+        print("{ ", end="")
+        print(f"{hex(peripheral.base + register.offset)}, ", end="")
+        print(f"{hex(register.reset)}, ", end="")
+        print(f"{hex(register.reset)}, ", end="")
+        print(f'"{peripheral.name}", ', end="")
+        print(f'"{register.name}", ', end="")
+
+        if register.read:
+            print("1, ", end="")
+        else:
+            print("0, ", end="")
+
+        if register.write:
+            print("1, ", end="")
+        else:
+            print("0, ", end="")
+
+        if is_unsafe(peripheral.name, register.name):
+            print("1", end="")
+        else:
+            print("0", end="")
+
+        print(" },")
+
+print("{ 0, 0, 0, NULL, NULL, 0, 0, 0 },")
+print("};")

src/.clangd

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+CompileFlags:
+  CompilationDatabase: ../build

src/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.21)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+include($ENV{PICO_SDK_PATH}/pico_sdk_init.cmake)
+
+project(pdmtest)
+pico_sdk_init()
+
+add_executable(pdmtest main.c)
+
+add_subdirectory(vendor/pico-stdio-usb-simple)
+
+target_link_libraries(
+  pdmtest
+  pico_stdio_usb_simple
+
+  pico_divider
+  pico_multicore
+  pico_stdlib
+  pico_util
+  hardware_adc
+  hardware_pwm
+  hardware_divider
+  hardware_dma
+  hardware_pio
+  hardware_timer
+  hardware_vreg
+)
+
+target_compile_definitions(pdmtest PRIVATE
+	PLL_SYS_REFDIV=1
+	PLL_SYS_VCO_FREQ_HZ=1584000000
+	PLL_SYS_POSTDIV1=6
+	PLL_SYS_POSTDIV2=2
+	SYS_CLK_HZ=132000000
+)
+
+pico_add_extra_outputs(pdmtest)
+
+set_property(TARGET pdmtest PROPERTY C_STANDARD 23)
+target_compile_options(pdmtest PRIVATE -Wall -Wextra -Wnull-dereference)
+target_compile_definitions(pdmtest PUBLIC PICO_MAX_SHARED_IRQ_HANDLERS=8u)
+target_compile_definitions(pdmtest PUBLIC PICO_STDIO_ENABLE_CRLF_SUPPORT=1)
+target_compile_definitions(pdmtest PUBLIC PICO_STDIO_DEFAULT_CRLF=1)
+
+target_include_directories(pdmtest PRIVATE include)
+
+#pico_set_binary_type(pdmtest no_flash)
+#pico_set_binary_type(pdmtest copy_to_ram)

src/main.c

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+#include <pico/stdlib.h>
+#include <pico/stdio_usb.h>
+
+#include <hardware/pwm.h>
+
+#include <stdio.h>
+
+#define IR_BIAS_PIN 3
+#define IR_RX_PIN 6
+#define IR_FB_PIN 7
+
+#define HP_GND_PIN 13
+#define HP_LEFT_PIN 14
+#define HP_RIGHT_PIN 15
+
+#define HP_GND_SLICE 6
+#define HP_GND_CHAN PWM_CHAN_B
+
+#define HP_LR_SLICE 7
+
+#define HP_PWM_RATE (16 * 48 * 1000)
+#define HP_PWM_SCALE (SYS_CLK_HZ / HP_PWM_RATE)
+#define HP_PWM_MID (HP_PWM_SCALE / 2)
+
+int main()
+{
+	stdio_usb_init();
+
+	for (int i = 0; i < 30; i++) {
+		if (stdio_usb_connected())
+			break;
+
+		sleep_ms(100);
+	}
+
+	printf("\nWelcome to PDM Test!\n");
+
+	gpio_disable_pulls(HP_GND_PIN);
+	gpio_disable_pulls(HP_LEFT_PIN);
+	gpio_disable_pulls(HP_RIGHT_PIN);
+
+	gpio_set_function(HP_GND_PIN, GPIO_FUNC_PWM);
+	gpio_set_function(HP_LEFT_PIN, GPIO_FUNC_PWM);
+	gpio_set_function(HP_RIGHT_PIN, GPIO_FUNC_PWM);
+
+	gpio_set_drive_strength(HP_GND_PIN, GPIO_DRIVE_STRENGTH_2MA);
+	gpio_set_drive_strength(HP_LEFT_PIN, GPIO_DRIVE_STRENGTH_2MA);
+	gpio_set_drive_strength(HP_RIGHT_PIN, GPIO_DRIVE_STRENGTH_2MA);
+
+	/* LR at 48 kHz */
+	pwm_config pc = pwm_get_default_config();
+	pwm_config_set_clkdiv_int(&pc, 1);
+	pwm_config_set_phase_correct(&pc, false);
+	pwm_config_set_wrap(&pc, HP_PWM_SCALE - 1);
+	pwm_init(HP_LR_SLICE, &pc, false);
+
+	/* GND at high rate, 50:50 for virtual ground */
+	pwm_config_set_wrap(&pc, 1);
+	pwm_init(HP_GND_SLICE, &pc, false);
+	pwm_set_chan_level(HP_GND_SLICE, HP_GND_CHAN, 1);
+
+	/* Start at 50:50. */
+	pwm_set_both_levels(HP_LR_SLICE, HP_PWM_MID, HP_PWM_MID);
+
+	/* Start both */
+	pwm_set_enabled(HP_GND_SLICE, true);
+	pwm_set_enabled(HP_LR_SLICE, true);
+
+	while (true) {
+		for (int i = 0; i < 50; i++) {
+			sleep_us(2272);
+			pwm_set_both_levels(HP_LR_SLICE, HP_PWM_MID + 1, HP_PWM_MID + 1);
+
+			sleep_us(2272);
+			pwm_set_both_levels(HP_LR_SLICE, HP_PWM_MID - 1, HP_PWM_MID - 1);
+		}
+
+		for (int i = 0; i < 55; i++) {
+			sleep_us(2020);
+			pwm_set_both_levels(HP_LR_SLICE, HP_PWM_MID + 1, HP_PWM_MID + 1);
+
+			sleep_us(2020);
+			pwm_set_both_levels(HP_LR_SLICE, HP_PWM_MID - 1, HP_PWM_MID - 1);
+		}
+
+		sleep_ms(500);
+	}
+}

src/vendor/pico-stdio-usb-simple

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+Subproject commit 0897a68ac3ca865715368ce824f49275222ed57e