New i2c implementation, support up to 4 faderbanks with teletype 5.0

firmware/mock_hardware/common/i2c.c

@@ -18,7 +18,7 @@ int i2c_leader_rx(uint8_t addr, uint8_t* data, uint8_t l)
 {
     if (l == 2)
     {
-        uint16_t value = hardware_iiGetFollowerData(addr << 8 | last_port);
+        uint16_t value = hardware_iiGetFollowerData(addr, last_port);
         data[0] = value >> 8;
         data[1] = value & 0xFF;
     }

firmware/mock_hardware/mock_hardware_api.c

@@ -238,22 +238,28 @@ void hardware_setScreenBuffer(uint8_t* buf)
     screenBuffer = buf;
 }
 
-// TODO: make this generic for all followers somehow
-uint16_t faderbank[16];
+// TODO: make this generic to support more follower types
+uint16_t faderbank[64];
 
-void hardware_iiUpdateFollowerData(uint16_t key, uint16_t data)
+void hardware_iiUpdateFollowerData(uint8_t device, uint8_t param, uint16_t data)
 {
-    if (key >> 8 == 0x34)
+    // For now, only support 16 params each on devices 0x34-0x37
+    uint8_t offset = device - 0x34;
+    if (offset < 4 && param < 16)
     {
-        faderbank[key & 0xFF] = data;
+        uint8_t index = offset * 16 + param;
+        faderbank[index] = data;
     }
 }
 
-uint16_t hardware_iiGetFollowerData(uint16_t key)
+uint16_t hardware_iiGetFollowerData(uint8_t device, uint8_t param)
 {
-    if (key >> 8 == 0x34)
+    // For now, only support 16 params each on devices 0x34-0x37
+    uint8_t offset = device - 0x34;
+    if (offset < 4 && param < 16)
     {
-        return faderbank[key & 0xFF];
+        uint8_t index = offset * 16 + param;
+        return faderbank[index];
     }
     return 0;
 }

firmware/mock_hardware/mock_hardware_api.h

@@ -50,8 +50,8 @@ MOCK_API(void, hidConnect, ());
 MOCK_API(void, hidDisconnect, ());
 MOCK_API(void, hidMessage, (uint8_t key, uint8_t mod, bool held, bool release));
 
-MOCK_API(void, iiUpdateFollowerData, (uint16_t key, uint16_t data));
-MOCK_API(uint16_t, iiGetFollowerData, (uint16_t key));
+MOCK_API(void, iiUpdateFollowerData, (uint8_t device, uint8_t param, uint16_t data));
+MOCK_API(uint16_t, iiGetFollowerData, (uint8_t device, uint8_t param));
 MOCK_API(bool, iiPushMessage, (uint8_t addr, uint8_t* data, uint8_t length));
 MOCK_API(bool, iiPopMessage, (uint8_t* addr, uint8_t* data, uint8_t* length));
 

src/common/core/FirmwareManager.cpp

@@ -459,11 +459,11 @@ void FirmwareManager::hidMessage(uint8_t key, uint8_t mod, bool held, bool relea
     }
 }
 
-void FirmwareManager::iiUpdateFollowerData(uint16_t key, uint16_t value)
+void FirmwareManager::iiUpdateFollowerData(uint8_t device, uint8_t param, uint16_t value)
 {
     if (impl)
     {
-        impl->fw_fn_hardware_iiUpdateFollowerData(key, value);
+        impl->fw_fn_hardware_iiUpdateFollowerData(device, param, value);
     }
 }
 

src/common/core/iiBus.cpp

@@ -1,55 +1,62 @@
-#include "iiBus.h"
+#include "IIBus.h"
+#include "LibAVR32Module.hpp"
 
-iiFollowerData_t iiBus::FollowerData;
+#define FADERBANK_II_MAX_VALUE 16383
 
-void iiBus::Initialize()
-{
-    for (int device = 0x34; device <= 0x37; device++) 
-    {
-        for (int fader = 0; fader < 16; fader++)
-        {
-            iiBus::FollowerData.emplace(std::make_pair((device << 8) | fader, 0));
-        }
-    }
-}
+extern rack::plugin::Model* modelFaderbank;
 
-iiDevice::iiDevice(rack::Module* module)
-: _module(module)
+IIBus::IIBus(LibAVR32Module* leader)
+    : leader(leader)
 {
-    if (_module) 
-    {
-        _module->rightExpander.producerMessage = new iiCommand();
-        _module->leftExpander.producerMessage = new iiCommand();
-    }
 }
 
-void iiDevice::setAddress(uint8_t address)
+bool IIBus::isFollower(rack::Module* module)
 {
-    _address = address;
+    // Only faderbanks participate in II right now
+    return module != nullptr && module->model == modelFaderbank;
 }
 
-void iiDevice::updateFollowerData(uint8_t id, uint16_t data)
+void IIBus::step()
 {
-    const auto record = iiBus::FollowerData.find((_address << 8) | id);
-    if (record != iiBus::FollowerData.end()) 
+    if (leader == nullptr)
     {
-        record->second.store(data, std::memory_order_relaxed);
+        return;
     }
-}
 
-void iiDevice::transmit(const iiCommand& msg)
-{
-    if (_module) 
+    // let's tentatively define a bus as an unbroken chain of II-supporting
+    // modules directly attached to either the left or right of the leader.
+
+    // scan the "bus" for eligible modules, starting to the leader's left
+    std::vector<rack::Module*> followers;
+    auto module = leader->getLeftExpander().module;
+    while (isFollower(module))
     {
-        if (_module->rightExpander.producerMessage)
-        {
-            *(reinterpret_cast<iiCommand*>(_module->rightExpander.producerMessage)) = msg;
-            _module->rightExpander.messageFlipRequested = true;
-        }
-        if (_module->leftExpander.producerMessage)
+        followers.push_back(module);
+        module = module->getLeftExpander().module;
+    }
+
+    // flip the order, so we can prioritize left-to-right
+    if (followers.size() > 1)
+    {
+        std::reverse(followers.begin(), followers.end());
+    }
+
+    // scan to the leader's right
+    module = leader->getRightExpander().module;
+    while (isFollower(module))
+    {
+        followers.push_back(module);
+        module = module->getRightExpander().module;
+    }
+
+    // gather params from all followers
+    for (size_t follower = 0; follower < std::min(static_cast<size_t>(4), followers.size()); follower++)
+    {
+        for (uint8_t fader = 0; fader < std::min(16, followers[follower]->getNumParams()); fader++)
         {
-            *(reinterpret_cast<iiCommand*>(_module->leftExpander.producerMessage)) = msg;
-            _module->leftExpander.messageFlipRequested = true;
+            float voltage = followers[follower]->params[fader].getValue();
+            uint16_t value = static_cast<uint16_t>(voltage / 10.0 * FADERBANK_II_MAX_VALUE);
+            leader->firmware.iiUpdateFollowerData(follower + 0x34, fader, value);
         }
     }
-}
+}

src/common/core/iiBus.h

@@ -6,40 +6,24 @@
 #include <unordered_map>
 #include <atomic>
 
-#define MAX_II_DATA_BYTES 8
-
-// i2c devices cannot wait on each other. Even if the Rack engine is using multiple threads,
-// a leader and follower may be executing on the same thread. 
-// Since the leader will block waiting on a request for data from a follower, we need to 
-// have the data ready in advance. Therefore all followers must continuously update a data
-// structure accessible to the leader with all data the leader could possible request. 
-
-// cheapo concurrent data structure for time-travelling follower data
-typedef std::unordered_map<uint16_t, std::atomic<uint16_t>> iiFollowerData_t;
-
-struct iiBus {
-    static void Initialize();
-    static iiFollowerData_t FollowerData;
-};
-
-// TODO: send commands from follower over Rack expander bus
-struct iiCommand
+struct LibAVR32Module;
+
+// Notes on the work-in-progress implementation of II (monome ecosystem i2c):
+//
+// An i2c module cannot wait for a response to messages. Even if the Rack engine is
+// using multiple threads, a leader and follower may be executing on the same thread.
+//
+// Since the leader will block waiting on a request for data from a follower, we need to
+// have the data ready in advance. Therefore the bus must continuously maintain a data
+// structure accessible to the leader with all data the leader could possibly request.
+
+struct IIBus
 {
-    // 7-bit I2C address
-    uint8_t address;
-    uint8_t data[MAX_II_DATA_BYTES];
-    uint8_t length;
-};
-
-struct iiDevice
-{
-    iiDevice(rack::Module* module);
+    IIBus(LibAVR32Module* leader);
+    bool isFollower(rack::Module* module);
 
-    void setAddress(uint8_t address);
-    void updateFollowerData(uint8_t id, uint16_t data);
-    void transmit(const iiCommand& msg);
+    void step();
 
 protected:
-    rack::Module* _module;
-    uint8_t _address; 
-};
+    LibAVR32Module* leader;
+};

src/faderbank/FaderbankModule.cpp

@@ -1,7 +1,5 @@
 #include "FaderbankModule.hpp"
 
-#define FADERBANK_II_MAX_VALUE 16383
-
 struct FBFaderParam : rack::engine::ParamQuantity
 {
     std::string getDisplayValueString() override
@@ -37,9 +35,6 @@ void FaderbankModule::process(const ProcessArgs& args)
     for (unsigned i = 0; i < NUM_FADERS; i++)
     {
         outputs[i].setVoltage(params[i].getValue());
-
-        // float iiValue = params[i].getValue() / 10.0 * FADERBANK_II_MAX_VALUE;
-        // _iiDevice.updateFollowerData(i, static_cast<uint16_t>(iiValue));
     }
 }
 

src/faderbank/FaderbankModule.hpp

@@ -1,6 +1,5 @@
 #pragma once
 #include "rack.hpp"
-#include "iiBus.h"
 
 #include <map>
 

src/plugin.cpp

@@ -17,6 +17,7 @@
 using namespace rack;
 
 Plugin* pluginInstance;
+Model* modelFaderbank;
 
 void init(Plugin* p)
 {
@@ -33,7 +34,7 @@ void init(Plugin* p)
     Model* modelGrid64 = createModel<VirtualGridModuleTemplate<8, 8>, VirtualGridWidgetTemplate<8, 8>>("grid64");
     Model* modelGrid256 = createModel<VirtualGridModuleTemplate<16, 16>, VirtualGridWidgetTemplate<16, 16>>("grid256");
 
-    Model* modelFaderbank = createModel<FaderbankModule, FaderbankWidget>("faderbank");
+    modelFaderbank = createModel<FaderbankModule, FaderbankWidget>("faderbank");
 
     p->addModel(modelWhiteWhale);
     p->addModel(modelMeadowphysics);

src/teletype/TeletypeModule.cpp

@@ -33,7 +33,7 @@ struct TTParamQuantity : rack::engine::ParamQuantity
 
 TeletypeModule::TeletypeModule()
 : LibAVR32Module("teletype", "teletype4")
-, _iiDevice(this)
+, iiBus(this)
 , screenBuffer{}
 {
     // initialize screen with "engine stopped" message
@@ -89,15 +89,9 @@ void TeletypeModule::processInputs(const ProcessArgs& args)
         firmware.setGPIO(A00 + i, inputTriggers[i].isHigh());
     }
 
-    // for (const auto& [key, value] : iiBus::FollowerData)
-    // {
-    //     firmware.iiUpdateFollowerData(key, value.load(std::memory_order_relaxed));
-    // }
-
-    // iiCommand msg;
-    // while (firmware.iiPopMessage(&msg.address, msg.data, &msg.length))  {
-    //     _iiDevice.transmit(msg);
-    // }
+    // process II follower-to-leader input
+    // no support for leader-to-follower commands right now
+    iiBus.step();
 }
 
 void TeletypeModule::processOutputs(const ProcessArgs& args)

src/teletype/TeletypeModule.hpp

@@ -1,5 +1,5 @@
 #include "LibAVR32Module.hpp"
-#include "iiBus.h"
+#include "IIBus.h"
 
 #include "rack.hpp"
 
@@ -64,7 +64,7 @@ struct TeletypeModule : LibAVR32Module
     virtual uint8_t* getScreenBuffer() override { return screenBuffer; }
 
 protected:
-    iiDevice _iiDevice;
+    IIBus iiBus;
 
     uint8_t screenBuffer[128 * 64];
 };