HoHCI-BikeSteering/Assets/Scripts/Sensors/ANT/PowerMeterReceiver.cs

using System.Collections.Generic;
using ANT_Managed_Library;
using UnityEngine;

namespace Sensors.ANT
{
    /*

    Frequencies such as 4.06 Hz (ANT+ Heart
Rate) and 4.005 Hz (ANT+ Bike Power) will
periodically “drift” into each other, or into
other channel periods that may be present
in the vicinity. During this overlap, channel
collisions may occur as the radio can only
service channel at a time. 
*/

    public struct PowermeterSensorData
    {
        public int InstantaneousPower; // the instantaneous power in watt
        public int InstantaneousCadence; // crank cadence in RPM if available ( 255 indicates invalid)
        public float CrankTorque;
    }

    public class PowerMeterReceiver
    {
        private readonly Dictionary<int, int> sameEventCounter = new Dictionary<int, int> {{0x10, 0}, {0x12, 0}};

        private readonly Dictionary<int, int> updateEventCount = new Dictionary<int, int> {{0x10, 0}, {0x12, 0}};
        private AntChannel backgroundScanChannel;
        private AntChannel deviceChannel;
        private byte[] pageToSend;

        private int previousAccumulatedTorqueValue;
        private int previousTorqueEventCount;
        private PowermeterSensorData sensorData;

        public PowerMeterReceiver()
        {
        }

        public PowerMeterReceiver(int deviceID)
        {
            DeviceID = deviceID;
        }

        public int DeviceID { get; }
        public bool Connected { get; private set; }
        public List<AntDevice> ScanResult { get; private set; }
        public PowermeterSensorData SensorData => sensorData;

        public void StartScan()
        {
            Debug.Log("Looking for ANT + power meter sensor");

            AntManager.Instance.Init();
            ScanResult = new List<AntDevice>();
            backgroundScanChannel = AntManager.Instance.OpenBackgroundScanChannel(0);
            backgroundScanChannel.onReceiveData += ReceivedBackgroundScanData;
        }


        private void ReceivedBackgroundScanData(byte[] data)
        {
            var deviceType = data[12]; // extended info Device Type byte

            switch (deviceType)
            {
                case AntplusDeviceType.BikePower:
                {
                    var deviceNumber = data[10] | (data[11] << 8);
                    var transType = data[13];
                    foreach (var d in ScanResult)
                        if (d.deviceNumber == deviceNumber && d.transType == transType) //device already found
                            return;

                    var foundDevice = new AntDevice();
                    foundDevice.deviceType = deviceType;
                    foundDevice.deviceNumber = deviceNumber;
                    foundDevice.transType = transType;
                    foundDevice.period = 8182;
                    foundDevice.radiofreq = 57;
                    foundDevice.name = "Powermeter(" + foundDevice.deviceNumber + ")";
                    ScanResult.Add(foundDevice);
                    if (deviceNumber == DeviceID)
                    {
                        Debug.Log($"Desired Power Sensor with id {deviceNumber} found!");
                        ConnectToDevice(foundDevice);
                    }
                    else
                    {
                        Debug.Log($"Power sensor ({deviceNumber}) found and added to ScanResult");
                    }

                    break;
                }
            }
        }

        private void ConnectToDevice(AntDevice device)
        {
            AntManager.Instance.CloseBackgroundScanChannel();
            var channelID = AntManager.Instance.GetFreeChannelID();
            deviceChannel = AntManager.Instance.OpenChannel(ANT_ReferenceLibrary.ChannelType.BASE_Slave_Receive_0x00,
                channelID, (ushort) device.deviceNumber, device.deviceType, device.transType, (byte) device.radiofreq,
                (ushort) device.period, false);
            Connected = true;
            deviceChannel.onReceiveData += Data;
            deviceChannel.onChannelResponse += ChannelResponse;

            deviceChannel.hideRXFAIL = true;
        }

        //Deal with the received Data
        private void Data(byte[] data)
        {
            if (data[0] == 0x10) // Standard Power-Only Main Data Page
            {
                if (data[1] == updateEventCount[0x10])
                    sameEventCounter[0x10]++;
                else
                    sameEventCounter[0x10] = 0;

                updateEventCount[0x10] = data[1];

                if (sameEventCounter[0x10] > 3)
                {
                    sensorData.InstantaneousPower = 0;
                    sensorData.InstantaneousCadence = 0;
                }
                else
                {
                    sensorData.InstantaneousPower = data[6] | (data[7] << 8);
                    sensorData.InstantaneousCadence = data[3];
                }
            }

            if (data[0] == 0x12) // Standard Crank Torque Main Data Page
            {
                Debug.Log($"Torque Data {data}");
                if (data[1] == updateEventCount[0x12])
                    sameEventCounter[0x12]++;
                else
                    sameEventCounter[0x12] = 0;

                updateEventCount[0x12] = data[1];

                if (sameEventCounter[0x12] > 3)
                {
                    sensorData.CrankTorque = 0;
                }
                else
                {
                    var accumulatedTorque = data[6] | (data[7] << 8);
                    float divisor = 32 * (updateEventCount[0x12] - previousTorqueEventCount);
                    if (divisor > 0)
                        sensorData.CrankTorque = (accumulatedTorque - previousAccumulatedTorqueValue) / divisor;
                    previousAccumulatedTorqueValue = accumulatedTorque;
                    previousTorqueEventCount = updateEventCount[0x12];
                }
            }
        }


        public void Calibrate()
        {
            Debug.Log("Sending : Manual Zero Calibration request");
            pageToSend = new byte[8] {0x01, 0xAA, 0x0FF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

            deviceChannel.sendAcknowledgedData(pageToSend);
        }

        private void ChannelResponse(ANT_Response response)
        {
            if (response.getChannelEventCode() == ANT_ReferenceLibrary.ANTEventID.EVENT_TRANSFER_TX_FAILED_0x06)
                deviceChannel.sendAcknowledgedData(pageToSend); //send the page again if the transfer failed
        }
    }
}