MURMULATOR2

src/CMakeLists.txt

@@ -100,6 +100,10 @@ set(zxspectrum_ear_in_pio
   ${CMAKE_CURRENT_LIST_DIR}/zx_ear_in.pio
 )
 
+set(zxspectrum_pwm_pio
+  ${CMAKE_CURRENT_LIST_DIR}/pwm.pio
+)
+
 add_subdirectory(hdmi)
 add_subdirectory(picomputer)
 add_subdirectory(vga)

src/ZxSpectrumAudio.cpp

@@ -1,13 +1,48 @@
 #include "ZxSpectrumAudio.h"
 #include "hardware/gpio.h"
 #include "hardware/clocks.h"
+#include "pico/printf.h"
 
 #ifndef INITIAL_VOL
 #define INITIAL_VOL 0x100
 #endif
 static uint32_t _vol = INITIAL_VOL;
 
-#if !defined(PICO_HDMI_AUDIO) && !defined(PICO_AUDIO_I2S)
+#if defined(PICO_PIO_PWM_AUDIO) 
+
+#include "pwm.pio.h"
+static uint pwm_audio_sm = 0;
+
+// Write `period` to the input shift register
+void pio_pwm_set_period(PIO pio, uint sm, uint32_t period) {
+    pio_sm_set_enabled(pio, sm, false);
+    pio_sm_put_blocking(pio, sm, period);
+    pio_sm_exec(pio, sm, pio_encode_pull(false, false));
+    pio_sm_exec(pio, sm, pio_encode_out(pio_isr, 32));
+    pio_sm_set_enabled(pio, sm, true);
+}
+
+void init_pio_pwm_audio() {
+
+  gpio_init(SPK_PIN);
+  gpio_set_dir(SPK_PIN, GPIO_OUT);
+
+  uint offset = pio_add_program(PICO_AUDIO_PWM_PIO, &pwm_program);
+  printf("Loaded PWM PIO at %u\n", offset);
+  pwm_audio_sm = pio_claim_unused_sm(PICO_AUDIO_PWM_PIO, true);
+  printf("Chosen %d for PWM PIO State machine\n", pwm_audio_sm);
+  pwm_program_init(PICO_AUDIO_PWM_PIO, pwm_audio_sm, offset, SPK_PIN);
+  pio_sm_set_clkdiv(PICO_AUDIO_PWM_PIO, pwm_audio_sm, 2.0);
+  pio_pwm_set_period(PICO_AUDIO_PWM_PIO, pwm_audio_sm, 1024);
+  printf("Finish configuring PWM PIO\n");
+}
+
+// Write `level` to TX FIFO. State machine will copy this into X.
+inline void pio_pwm_set_level(PIO pio, uint sm, uint32_t level) {
+    pio_sm_put_blocking(pio, sm, level);
+}
+
+#elif !defined(PICO_HDMI_AUDIO) && !defined(PICO_AUDIO_I2S)
 #include "pico/time.h"
 // PWM Audio stuff
 #define ZX_AUDIO_BUF_SIZE_BITS 7
@@ -249,8 +284,9 @@ bool __not_in_flash_func(zxSpectrumEarReady)() {
 }
 
 void zxSpectrumAudioInit() {
-
-#if defined(PICO_AUDIO_I2S)
+#if defined(PICO_PIO_PWM_AUDIO)
+  init_pio_pwm_audio();
+#elif defined(PICO_AUDIO_I2S)
   init_is2_audio();
 #elif defined(PICO_HDMI_AUDIO)
   init_hdmi_audio();
@@ -280,15 +316,21 @@ void zxSpectrumAudioInit() {
 }
 
 void __not_in_flash_func(zxSpectrumAudioHandler)(uint32_t vA, uint32_t vB, uint32_t vC, int32_t s, uint32_t buzzer, bool mute) {
-#if defined(PICO_HDMI_AUDIO) || defined(PICO_AUDIO_I2S)
+#if defined(PICO_PIO_PWM_AUDIO)
+  const int32_t l = vA + vC + vB + s - (128*3);
+  const int32_t v = __mul_instruction(_vol, 60);
+  const int32_t lr = __mul_instruction(v, l) >> (8 + 6);
+  const int32_t k = lr + 512;
+  pio_pwm_set_level(PICO_AUDIO_PWM_PIO, pwm_audio_sm, k < 0 ? 0 : k > 1024 ? 1024 : k);
+#elif defined(PICO_HDMI_AUDIO) || defined(PICO_AUDIO_I2S)
   uint32_t ll, rr;
   if (mute) {
     ll = rr = 0;
   }
   else {
-    const uint32_t l = (vA << 1) + vB + s + 128;
-    const uint32_t r = (vC << 1) + vB + s + 128;
-    const uint32_t v = _vol << 4;
+    const int32_t l = (vA << 1) + vB + s - (128*3);
+    const int32_t r = (vC << 1) + vB + s - (128*3);
+    const int32_t v = __mul_instruction(_vol, 60);
     ll = (__mul_instruction(v, l) >> 8) & 0xffff;
     rr = (__mul_instruction(v, r) >> 8) & 0xffff;
   }
@@ -330,7 +372,10 @@ uint32_t zxSpectrumAudioGetVolume() { return _vol; }
 void zxSpectrumAudioSetVolume(uint32_t vol) { _vol = vol; }
 
 bool __not_in_flash_func(zxSpectrumAudioReady)() {
-#if defined(PICO_HDMI_AUDIO)
+#if defined(PICO_PIO_PWM_AUDIO)
+  return !pio_sm_is_tx_fifo_full(PICO_AUDIO_PWM_PIO, pwm_audio_sm);
+  // return !(PICO_AUDIO_PWM_PIO->fstat & (1u << (pwm_audio_sm + PIO_FSTAT_TXFULL_LSB)));
+#elif defined(PICO_HDMI_AUDIO)
   return get_write_size(&dvi0.audio_ring, true) > 0;
 #elif defined(PICO_AUDIO_I2S)
   return is2_audio_ready();

src/ZxSpectrumMenu.cpp

@@ -519,13 +519,13 @@ ZxSpectrumMenu::ZxSpectrumMenu(
   };
 
   onPaint([](PicoPen *pen) {
-#ifdef MURMULATOR    
-     pen->printAt(0, 0, false, "ZX Spectrum 48K/128K by fruit-bat on MURMULATOR");
+#ifdef ZX_PLATFORM
+     pen->printAtF(0, 0, false, "ZX Spectrum 48K/128K by fruit-bat on %s", ZX_PLATFORM);
 #else
      pen->printAt(0, 0, false, "ZX Spectrum 48K/128K by fruit-bat");
 #endif
-     pen->printAtF(0, 1, false, "on %s Pico Pi at %3.1fMhz", PICO_MCU, (float)clock_get_hz(clk_sys) / 1000000.0);
-     pen->printAtF(0, 2, false, "Menu System version %d.%d", ZX_VERSION_MAJOR, ZX_VERSION_MINOR);
+     pen->printAtF(0, 1, false, "Build: %s", __DATE__);
+     pen->printAtF(0, 2, false, "CPU: %s @%3.1fMhz", PICO_MCU, (float)clock_get_hz(clk_sys) / 1000000.0);
 
      pen->printAt(0, SZ_FRAME_ROWS-1, false, "F1 to exit menu");
      pen->printAt(SZ_FRAME_COLS-14, SZ_FRAME_ROWS-1, false, "ESC to go back");

src/hdmi/CMakeLists.txt

@@ -417,8 +417,8 @@ set(zxspectrum_murmulator_hdmi_nespad_defines
 )
 
 set(murmulator_common_defines
+  ZX_PLATFORM="MURMULATOR"
   # Set up the DVI output to match the MURMULATOR board
-  MURMULATOR
   PICO_CORE1_STACK_SIZE=0x400
   DVI_DEFAULT_SERIAL_CONFIG=pimoroni_demo_hdmi_cfg
   DVI_VERTICAL_REPEAT=2
@@ -552,8 +552,8 @@ set(zxspectrum_murmulator2_hdmi_nespad_defines
 )
 
 set(murmulator2_common_defines
+  ZX_PLATFORM="MURMULATOR2"
   # Set up the DVI output to match the MURMULATOR board
-  MURMULATOR
   DVI_CUSTOM_CONFIG
   DVI_DEFAULT_SERIAL_CONFIG=murmulator2_hdmi_cfg
   PICO_CORE1_STACK_SIZE=0x400
@@ -572,23 +572,24 @@ set(murmulator2_common_defines
   # Use the alternate volume map
   AY8912_ALT_VOL_MAP  
   # Tape audio in
-  EAR_PIN=22
+  #EAR_PIN=22
   # Enable the PS/2 keyboard
   USE_PS2_KBD
   PS2KBD_CLK2_DAT
 )
 
 set(murmulator2_pwm_audio_defines
-  # Speaker pin audio
+  # Speaker pin audio (@270MHz)
+  PICO_PWM_AUDIO_FREQ=45000
+  PICO_AUDIO_PWM_PIO=pio1
+  PICO_PIO_PWM_AUDIO
   SPK_PIN=10
-  # Buzzer audio out
-  # BZR_PIN=10
   # STEREO AY audio
-  AY8912_ABC_STEREO
+#  AY8912_ABC_STEREO
   # Left chanel audio out
-  AY8912_A_PIN=9
+#  AY8912_A_PIN=9
   # Right chanel audio out
-  AY8912_C_PIN=11
+#  AY8912_C_PIN=11
 )
 
 set (zxspectrum_murmulator2_i2saudio_defines
@@ -631,6 +632,10 @@ foreach(target
     ${zxspectrum_audio_i2s_pio}
   )
 
+  pico_generate_pio_header(${target} 
+    ${zxspectrum_pwm_pio}
+  )
+
   # create map/bin/hex file etc.
   pico_add_extra_outputs(${target}) 
  

src/pwm.pio

@@ -0,0 +1,32 @@
+;
+; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+;
+; SPDX-License-Identifier: BSD-3-Clause
+;
+
+; Side-set pin 0 is used for PWM output
+.pio_version 0 // only requires PIO version 0
+
+.program pwm
+.side_set 1 opt
+
+    pull noblock    side 0 ; Pull from FIFO to OSR if available, else copy X to OSR.
+    mov x, osr             ; Copy most-recently-pulled value back to scratch X
+    mov y, isr             ; ISR contains PWM period. Y used as counter.
+countloop:
+    jmp x!=y noset         ; Set pin high if X == Y, keep the two paths length matched
+    jmp skip        side 1
+noset:
+    nop                    ; Single dummy cycle to keep the two paths the same length
+skip:
+    jmp y-- countloop      ; Loop until Y hits 0, then pull a fresh PWM value from FIFO
+
+% c-sdk {
+static inline void pwm_program_init(PIO pio, uint sm, uint offset, uint pin) {
+   pio_gpio_init(pio, pin);
+   pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
+   pio_sm_config c = pwm_program_get_default_config(offset);
+   sm_config_set_sideset_pins(&c, pin);
+   pio_sm_init(pio, sm, offset, &c);
+}
+%}

src/vga/CMakeLists.txt

@@ -255,7 +255,7 @@ target_compile_definitions(ZxSpectrumPicoMiteVGA_640x480x60Hz PRIVATE
 # ZX MURMULATOR
 #========================================================
 set(ZX-MURMULATOR_VGA_defines
-  MURMULATOR
+  ZX_PLATFORM=MURMULATOR
   # Configure the SPI sd card to use SPI0
   SDCARD_PIN_SPI0_CS=5
   SDCARD_PIN_SPI0_SCK=2
@@ -348,7 +348,7 @@ target_compile_definitions(ZX-MURMULATOR_VGA_I2S_AUDIO_720x576x50Hz PRIVATE
 # ZX MURMULATOR2
 #========================================================
 set(ZX-MURMULATOR2_VGA_defines
-  MURMULATOR
+  ZX_PLATFORM=MURMULATOR2
   # Configure the SPI sd card to use SPI0
   SDCARD_PIN_SPI0_CS=5
   SDCARD_PIN_SPI0_SCK=6
@@ -382,15 +382,15 @@ set(ZX-MURMULATOR2_VGA_defines
 
 set(ZX-MURMULATOR2_VGA_PWM_Audio_defines
   # Speaker pin audio
-  SPK_PIN=10
+  SPK_PIN=9
   # Buzzer audio out
   # BZR_PIN=10
   # STEREO AY audio
   AY8912_ABC_STEREO
   # Left chanel audio out
-  AY8912_A_PIN=9
+  AY8912_A_PIN=11
   # Right chanel audio out
-  AY8912_C_PIN=11
+  AY8912_C_PIN=10
 )
 
 set (ZX-MURMULATOR2_VGA_I2S_Audio_defines