working on speaker conversion

This commit is contained in:
Jorj Bauer 2020-07-09 20:31:51 -04:00
parent e17fb71d3d
commit 27e023f8ea
3 changed files with 94 additions and 25 deletions

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@ -1,13 +1,24 @@
#include <Arduino.h> #include <Arduino.h>
#include <softspi.h>
#include <TeensyThreads.h>
#include "teensy-speaker.h" #include "teensy-speaker.h"
#include "teensy-println.h"
#include "globals.h" #include "globals.h"
TeensySpeaker::TeensySpeaker(uint8_t pinNum) : PhysicalSpeaker() Threads::Mutex togmutex;
#define BUFSIZE 4096
EXTMEM uint32_t toggleBuffer[BUFSIZE]; // cycle counts at which state toggles
uint16_t headptr, tailptr;
uint32_t lastCycleCount, toggleAtCycle;
// How many cycles do we run the audio behind? Needs to be more than our bulk
// cycle count.
#define CYCLEDELAY 100
TeensySpeaker::TeensySpeaker(uint8_t sda, uint8_t scl) : PhysicalSpeaker()
{ {
toggleState = false; toggleState = false;
speakerPin = pinNum;
pinMode(speakerPin, OUTPUT); // analog speaker output, used as digital volume control
mixerValue = numMixed = 0; mixerValue = numMixed = 0;
} }
@ -15,24 +26,69 @@ TeensySpeaker::~TeensySpeaker()
{ {
} }
void TeensySpeaker::toggle(uint32_t c) void TeensySpeaker::begin()
{ {
toggleState = !toggleState; lastCycleCount = g_cpu->cycles;
toggleState = false;
mixerValue = (toggleState ? 0x1FF : 0x00); memset(toggleBuffer, 0, sizeof(toggleBuffer));
mixerValue >>= (16-g_volume); headptr = tailptr = 0;
// FIXME: this is one helluva hack
if (g_volume >= 8)
digitalWrite(speakerPin, toggleState ? HIGH : LOW);
//analogWrite(speakerPin, mixerValue);
} }
void TeensySpeaker::maintainSpeaker(uint32_t c, uint64_t runtimeInMicros) void TeensySpeaker::toggle(uint32_t c)
{ {
// Nothing to do here. We can't run the speaker async, b/c not Threads::Scope lock(togmutex);
// enough CPU time. So we run the CPU close to sync and hope that // Queue the speaker toggle time; maintainSpeaker will pick it up
// the direct pulsing of the speaker is reasonably close to on-time. toggleBuffer[tailptr++] = c; tailptr %= BUFSIZE;
}
void TeensySpeaker::maintainSpeaker(uint32_t c, uint64_t microseconds)
{
begin(); // flush! Hack. FIXME.
}
void TeensySpeaker::maintainSpeaker()
{
Threads::Scope lock(togmutex);
// This is called @ SAMPLERATE (8k, as of this writing) and looks for
// any transitions that have passed before sending data to the DAC.
// The idea is that this will be called fast enough for the given number
// of cycles that we run behind, so that the buffer can't overflow.
//
// at 8kHz, that means that .000125 seconds have passed since our last
// call; where the CPU has executed about 128 instructions in the same
// time. Therefore, it can't have toggled more than 128 times. We're
// also trying to stay 100 cycles "behind", so it's possible that we have
// 228 cycles difference between an event that just fired-and-queued,
// and where we need to catch up to in this loop.
// First, reconcile the "correct" toggleState. We pretend it's currently
// some time in the past, based on our cycle delay. In theory (as above),
// this shouldn't be more than about 228 cycles off (maybe slightly more,
// since we actually run cycles in batches).
uint32_t curTime = g_cpu->cycles - CYCLEDELAY;
// And then find any events that should have happened, accounting for them:
while (headptr != tailptr) {
if (curTime >= toggleBuffer[headptr]) {
toggleState = !toggleState;
headptr++; headptr %= BUFSIZE;
} else {
// The time to deal with this one has not come yet, so we're done for now
break;
}
}
// Now we can safely update the DAC based on the current toggleState
uint16_t v = (toggleState ? 0x1FF : 0x0);
uint8_t configbits =
(0 << 3) | // channel (A/B; A=0)
(0 << 2) | // buffered (no)
(1 << 1) | // gain (1 = 1x; 0 = 2x)
1; // keep channel active
uint8_t b = ((configbits << 4) | (v & 0xF00)) >> 8;
uint8_t b2 = (v & 0xFF);
spi_send(b);
spi_send(b2);
} }
void TeensySpeaker::beginMixing() void TeensySpeaker::beginMixing()

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@ -2,23 +2,25 @@
#define __TEENSY_SPEAKER_H #define __TEENSY_SPEAKER_H
#include "physicalspeaker.h" #include "physicalspeaker.h"
#include <MCP492X.h>
#define SAMPLERATE 8000
class TeensySpeaker : public PhysicalSpeaker { class TeensySpeaker : public PhysicalSpeaker {
public: public:
TeensySpeaker(uint8_t pinNum); TeensySpeaker(uint8_t sda, uint8_t scl);
virtual ~TeensySpeaker(); virtual ~TeensySpeaker();
virtual void begin() {}; virtual void begin();
virtual void toggle(uint32_t c); virtual void toggle(uint32_t c);
virtual void maintainSpeaker(uint32_t c, uint64_t runtimeInMicros); virtual void maintainSpeaker();
virtual void maintainSpeaker(uint32_t c, uint64_t microseconds);
virtual void beginMixing(); virtual void beginMixing();
virtual void mixOutput(uint8_t v); virtual void mixOutput(uint8_t v);
private: private:
uint8_t speakerPin;
bool toggleState; bool toggleState;
uint32_t mixerValue; uint32_t mixerValue;

View File

@ -38,6 +38,7 @@ TeensyUSB usb;
int cpuThreadId; int cpuThreadId;
int displayThreadId; int displayThreadId;
int maintenanceThreadId; int maintenanceThreadId;
int speakerThreadId;
int biosThreadId = -1; int biosThreadId = -1;
Bounce resetButtonDebouncer = Bounce(); Bounce resetButtonDebouncer = Bounce();
@ -109,7 +110,7 @@ void setup()
pinMode(SPEAKERPIN, OUTPUT); // analog speaker output, used as digital volume control pinMode(SPEAKERPIN, OUTPUT); // analog speaker output, used as digital volume control
println("creating virtual hardware"); println("creating virtual hardware");
g_speaker = new TeensySpeaker(SPEAKERPIN); g_speaker = new TeensySpeaker(18, 19); // FIXME abstract constants
println(" fm"); println(" fm");
// First create the filemanager - the interface to the host file system. // First create the filemanager - the interface to the host file system.
@ -176,12 +177,14 @@ void setup()
cpuThreadId = threads.addThread(runCPU); cpuThreadId = threads.addThread(runCPU);
displayThreadId = threads.addThread(runDisplay); displayThreadId = threads.addThread(runDisplay);
maintenanceThreadId = threads.addThread(runMaintenance); maintenanceThreadId = threads.addThread(runMaintenance);
speakerThreadId = threads.addThread(runSpeaker);
// Set the relative priorities of the threads by defining how long a "slice" // Set the relative priorities of the threads by defining how long a "slice"
// is for each (in 100uS "ticks") // is for each (in 100uS "ticks")
// At a ratio of 50:10:1, we get about 30FPS and 100% CPU speed. // At a ratio of 50:10:1, we get about 30FPS and 100% CPU speed.
threads.setTimeSlice(displayThreadId, 100); threads.setTimeSlice(displayThreadId, 100);
threads.setTimeSlice(cpuThreadId, 20); threads.setTimeSlice(cpuThreadId, 20);
threads.setTimeSlice(maintenanceThreadId, 1); threads.setTimeSlice(maintenanceThreadId, 1);
threads.setTimeSlice(speakerThreadId, 3); // guessing at a good value
} }
// FIXME: move these memory-related functions elsewhere... // FIXME: move these memory-related functions elsewhere...
@ -257,8 +260,16 @@ void biosInterrupt()
g_keyboard->maintainKeyboard(); g_keyboard->maintainKeyboard();
} }
//bool debugState = false; void runSpeaker()
//bool debugLCDState = false; {
uint32_t nextRuntime = 0;
while (1) {
if (micros() > nextRuntime) {
nextRuntime = micros() + ((float)1000000/(float)SAMPLERATE); // 125 uS per cycle @ 8k sample rate
((TeensySpeaker *)g_speaker)->maintainSpeaker();
}
}
}
// FIXME: how often does this really need to run? We can threads.yield() when we're running too quickly // FIXME: how often does this really need to run? We can threads.yield() when we're running too quickly
void runMaintenance() void runMaintenance()