/// <summary>
/// Command RHA2000-EVAL board to manually step the analog MUX to the next amplifier channel.
/// This is only used for electrode impedance checking.
/// </summary>
public void ChannelStep()
{
// The RHA2000-EVAL board is controlled by sending one-byte ASCII command characters over
// the USB interface. The 'N' character commands the board to manually step the analog MUX
// to the next amplifier channel. This command is only used for electrode impedance checking.
UInt32 numBytesWritten = 0;
Byte[] myChars = { 78, 115 }; // 'N' = step to next channel (impedance check mode)
if (running)
{
myChars[1] = 83;
}
FTDI.FT_STATUS ftStatus = ftdiDeviceA.Write(myChars, 2, ref numBytesWritten);
// Purge receive buffer.
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Could not write to Intan USB device");
throw e;
}
}
/// <summary>
/// Command RHA2000-EVAL board to enable amplifier fast settle.
/// </summary>
public void SettleOn()
{
// The RHA2000-EVAL board is controlled by sending one-byte ASCII command characters over
// the USB interface. The 'F' character commands the board to enable amplfier fast settle.
UInt32 numBytesWritten = 0;
Byte[] myChars = { 70, 115 }; // 'F' = fast settle on
if (running)
{
myChars[1] = 83;
}
FTDI.FT_STATUS ftStatus = ftdiDeviceA.Write(myChars, 2, ref numBytesWritten);
// Purge receive buffer.
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Could not write to Intan USB device");
throw e;
}
}
/// <summary>
/// Command RHA2000-EVAL board to disable impedance check mode.
/// </summary>
public void ZCheckOff()
{
// The RHA2000-EVAL board is controlled by sending one-byte ASCII command characters over
// the USB interface. The 'Z' character commands the board to disable impedance check mode.
UInt32 numBytesWritten = 0;
Byte[] myChars = { 122, 115 }; // 'z' = impedance check off
if (running)
{
myChars[1] = 83;
}
FTDI.FT_STATUS ftStatus = ftdiDeviceA.Write(myChars, 2, ref numBytesWritten);
// Purge receive buffer.
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Could not write to Intan USB device");
throw e;
}
}
/// <summary>
/// Command RHA2000-EVAL board to start streaming amplifier data to PC.
/// </summary>
public void Start()
{
FTDI.FT_STATUS ftStatus;
// Purge receive buffer
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
// The RHA2000-EVAL board is controlled by sending one-byte ASCII command characters over
// the USB interface. The 'S' character commands the board to start streaming amplifier
// data to the PC.
UInt32 numBytesWritten = 0;
Byte[] myChars = { 83 }; // 'S' = start data transfer
ftStatus = ftdiDeviceA.Write(myChars, 1, ref numBytesWritten);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Could not write to Intan USB device");
throw e;
}
// Resync to channel 0.
this.ResyncA();
running = true;
dataJustStarted = true;
}
/// <summary>
/// Search for the '001111xx' byte that designates the end of a 16-channel data packet.
/// </summary>
/// <returns>Number of bytes we skipped trying to get back in sync.</returns>
public int ResyncA()
{
bool inSync = false;
FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK;
byte[] resyncBuffer = new byte[1];
Debug.WriteLine("Resync #" + resyncCount.ToString());
resyncCount++;
int resyncBytes = 0;
while (inSync == false)
{
// Wait until the desired number of bytes have been received.
UInt32 numBytesAvailable = 0;
while (numBytesAvailable < 1)
{
ftStatus = ftdiDeviceA.GetRxBytesAvailable(ref numBytesAvailable);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Failed to get number of USB bytes available to read");
throw e;
}
}
// Now that we have the amount of data we want available, read it.
UInt32 numBytesRead = 0;
ftStatus = ftdiDeviceA.Read(resyncBuffer, 1, ref numBytesRead);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("USB read error");
throw e;
}
resyncDataBufferA[resyncBytes] = resyncBuffer[0];
resyncBytes++;
// Are we back in sync?
if ((resyncBuffer[0] & 0xfc) == 0x3c)
{
inSync = true;
}
}
return(resyncBytes);
}
/// <summary>
/// Command RHA2000-EVAL board to stop streaming amplifier data to PC.
/// </summary>
public void Stop()
{
// The RHA2000-EVAL board is controlled by sending one-byte ASCII command characters over
// the USB interface. The 's' character commands the board to stop streaming amplifier
// data to the PC.
UInt32 numBytesWritten = 0;
Byte[] myChars = { 115 }; // 's' = stop data transfer
FTDI.FT_STATUS ftStatus;
ftStatus = ftdiDeviceA.Write(myChars, 1, ref numBytesWritten);
// Purge receive buffer.
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Could not write to Intan USB device");
throw e;
}
running = false;
}
/// <summary>
/// Check to see if there is at least 30 msec worth of data in the USB read buffer.
/// </summary>
/// <param name="plotQueue">Queue used for plotting data to screen.</param>
/// <param name="saveQueue">Queue used for saving data to disk.</param>
public IntanUsbData ReadUsbData()
{
// Note: Users must call CheckForUsbData periodically during time-consuming operations (like updating graphics)
// to make sure the USB read buffer doesn't overflow!
FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK;
const UInt32 numBytesToRead = 36000; // 36000 / (3 bytes/sample x 16 channels x 25 kS/s) = 30 msec of data
// It seems that the FTDI read buffer is slightly less than 64000 bytes
// in size, so we must read from the buffer before it overflows. However,
// if we read a small number of bytes at a time, data transfer is slow.
// Empirically, waiting for 36000 bytes seems to work well.
UInt32 numBytesReadA = 0;
ftStatus = ftdiDeviceA.Read(readDataBufferA, numBytesToRead, ref numBytesReadA);
if (numBytesReadA != numBytesToRead)
{
throw new IntanUsbException("Data out of sync!!");
}
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("USB read error");
throw e;
}
// The following section of code reads and parses a block of data from the RHA2000-EVAL board.
// A complete sequence of single A/D samples from all 16 amplifiers uses 16 x 3 = 48 bytes in
// the following three-byte format (MSB is on the left; LSB is on the right):
//
// Byte 1: 1 ADC6 ADC5 ADC4 ADC3 ADC2 ADC1 ADC0
// Byte 2: 1 ADC13 ADC12 ADC11 ADC10 ADC9 ADC8 ADC7
// Byte 3: 0 0 CH3 CH2 CH1 CH0 ADC15 ADC14
//
// ADC0 through ADC 15 comprise the 16-bit A/D converter sample from a particular amplifier
// channel. (ADC15 is the MDB; ADC0 is the LSB.) The A/D full-scale range is 2.5V. The "zero"
// level of RHA2000 amplifiers is around 1.225V, although this can vary from one channel to another
// due to built-in offset voltages. The use of a software high-pass filter is recommended to
// remove these offsets (see the RHA2000 series datasheet for more information). With the RHA2000
// gain of 200 taken into account, each A/D step corresponds to an electrode-referred voltage of
// (2.5V/200)/(2^16) = 0.19073 microvolts.
//
// CH0 through CH3 encode information that varies with the channel number. The following table
// shows the values for these bits depending on the channel:
//
// Amplifier Channel CH3 CH2 CH1 CH0
// 0 0 0 0 0
// 1 0 0 0 AUX1
// 2 0 0 0 AUX2
// 3 0 0 0 AUX3
// 4 0 0 0 AUX4
// 5 0 0 0 AUX5
// 6 0 0 0 AUX6
// 7 X X X X
// 8 X X X X
// 9 X X X X
// 10 X X X X
// 11 X X X X
// 12 X X X X
// 13 X X X X
// 14 X X X X
// 15 1 1 1 1
//
// AUX1 through AUX6 are bits corresponding to the Port J3 auxiliary TTL inputs shown in the
// RHA2000-EVAL datasheet. Any bits listed as 'X' are not specified and should not be used.
// Note that channels 0 and 15 are unambiguously marked (0000 and 1111, respectively). It is
// recommended that interface software first watch for a byte that begins with '001111xx'.
// This must correspond to byte 3 of channel 15. The next 48 bytes will comprise a complete
// 16-channel data frame starting with channel 0 and proceeding through channel 15.
//
// Each amplifier channel is sampled at 25 kS/s, which gives a data rate of 25,000 x 16 x 3 =
// 1.2 MByte/s.
//
// In our experience, the FTDI USB interface chip on the RHA2000-EVAL occasionally drops bytes
// (though this seems to depend on the exact USB interface card used in the PC), requiring any
// interface software to frequently look for a '001111xx' byte at the end of each 48-byte data
// frame to ensure synchronization is maintained. When sync is lost, the software must search
// for this byte again.
// Are we out of sync due to a dropped byte over the USB link? If so, resync.
if ((readDataBufferA[35999] & 0xfc) != 0x3c) // look for '001111xx' byte
{
// for (int j = 0; j < 36000; j++)
// {
// if ((readDataBufferA[j] & 0xfc) == 0x3c)
// {
// Debug.WriteLine("readDataBufferA[" + j + "] = 0x3C.");
// break;
// }
// }
int i = 0;
int index = 0;
int numExtraBytes = this.ResyncA();
Debug.WriteLine("Resync " + numExtraBytes + " bytes.");
int indexError = 47 + 48;
while ((readDataBufferA[indexError] & 0xfc) == 0x3c)
{
indexError += 48;
}
Debug.WriteLine("indexError = " + indexError);
// Duplicate previous sample to 'patch' missing or erroneous data
for (i = indexError - 47; i < indexError + 1; i++)
{
readDataBufferA[i] = readDataBufferA[i - 48];
}
for (i = indexError - 47 + 48; i < 36000 - numExtraBytes; i++)
{
readDataBufferA[i] = readDataBufferA[i + numExtraBytes];
}
for (i = 36000 - numExtraBytes; i < 36000; i++)
{
readDataBufferA[i] = resyncDataBufferA[index++];
}
}
// Parse data (see comments above for description of 3-byte data packet)
int indexA = 0;
byte byte1, byte2, byte3;
for (int i = 0; i < 750; i++)
{
auxFrame[i] = 0;
for (int channel = 0; channel < 16; channel++)
{
byte1 = readDataBufferA[indexA++];
byte2 = readDataBufferA[indexA++];
byte3 = readDataBufferA[indexA++];
if (channel == 1)
{
auxFrame[i] += (UInt16)(1 * (int)((byte3 & 0x04) >> 2));
}
else if (channel == 2)
{
auxFrame[i] += (UInt16)(2 * (int)((byte3 & 0x04) >> 2));
}
else if (channel == 3)
{
auxFrame[i] += (UInt16)(4 * (int)((byte3 & 0x04) >> 2));
}
else if (channel == 4)
{
auxFrame[i] += (UInt16)(8 * (int)((byte3 & 0x04) >> 2));
}
else if (channel == 5)
{
auxFrame[i] += (UInt16)(16 * (int)((byte3 & 0x04) >> 2));
}
else if (channel == 6)
{
auxFrame[i] += (UInt16)(32 * (int)((byte3 & 0x04) >> 2));
}
dataRaw[channel, i] = 0.1907F * (16384.0F * Convert.ToSingle(byte3 & 0x03) +
128.0F * Convert.ToSingle(byte2 & 0x7f) + Convert.ToSingle(byte1 & 0x7f)) - 6175.0F; // 6175 = 1.235 V offset divided by 200, expressed in microvolts
}
}
if (dataJustStarted)
{
for (int channel = 0; channel < 16; channel++)
{
dataState[channel] = dataRaw[channel, 0];
dataDelay1[channel] = dataRaw[channel, 0];
dataDelay2[channel] = dataRaw[channel, 0];
notchDelay1[channel] = dataRaw[channel, 0];
notchDelay2[channel] = dataRaw[channel, 0];
}
dataJustStarted = false;
}
// Apply software first-order high-pass filter
// (See RHA2000 series datasheet for desciption of this algorithm.)
const double FSample = 25000.0; // ADC sample rate, in Hz
float filtA = (float)(Math.Exp(-2.0 * Math.PI * fHPF / FSample)); // A
float filtB = 1.0F - filtA; // B = 1 - A
for (int channel = 0; channel < 16; channel++)
{
dataState[channel] = filtA * dataState[channel] + filtB * dataRaw[channel, 0];
if (enableHPF)
{
dataFrame[channel, 0] = dataRaw[channel, 0] - dataState[channel];
}
else
{
dataFrame[channel, 0] = dataRaw[channel, 0];
}
for (int i = 1; i < 750; i++)
{
dataState[channel] = filtA * dataState[channel] + filtB * dataRaw[channel, i];
if (enableHPF)
{
dataFrame[channel, i] = dataRaw[channel, i] - dataState[channel];
}
else
{
dataFrame[channel, i] = dataRaw[channel, i];
}
}
}
// Apply software notch filter
// (See RHA2000 series datasheet for desciption of this algorithm.)
const double NotchBW = 10.0; // notch filter bandwidth, in Hz
// Note: Reducing the notch filter bandwidth will create a more frequency-selective filter, but this
// can lead to a long settling time for the filter. Selecting a bandwdith of 10 Hz (e.g., filtering
// out frequencies between 55 Hz and 65 Hz for the 60 Hz notch filter setting) implements a fast-
// settling filter.
float d = (float)Math.Exp(-1.0 * Math.PI * NotchBW / FSample);
float b = (1.0F + d * d) * (float)Math.Cos(2.0 * Math.PI * fNotch / FSample);
float a = 0.5F * (1.0F + d * d);
float b0 = a;
float b1 = a * (-2.0F) * (float)Math.Cos(2.0 * Math.PI * fNotch / FSample);
float b2 = a;
float a1 = -b;
float a2 = d * d;
for (int channel = 0; channel < 16; channel++)
{
dataNotch[channel, 0] = b2 * dataDelay2[channel] + b1 * dataDelay1[channel] + b0 * dataFrame[channel, 0] - a2 * notchDelay2[channel] - a1 * notchDelay1[channel];
dataNotch[channel, 1] = b2 * dataDelay1[channel] + b1 * dataFrame[channel, 0] + b0 * dataFrame[channel, 1] - a2 * notchDelay1[channel] - a1 * dataNotch[channel, 0];
for (int i = 2; i < 750; i++)
{
dataNotch[channel, i] = b2 * dataFrame[channel, i - 2] + b1 * dataFrame[channel, i - 1] + b0 * dataFrame[channel, i] - a2 * dataNotch[channel, i - 2] - a1 * dataNotch[channel, i - 1];
}
}
for (int channel = 0; channel < 16; channel++)
{
dataDelay2[channel] = dataFrame[channel, 748];
dataDelay1[channel] = dataFrame[channel, 749];
notchDelay2[channel] = dataNotch[channel, 748];
notchDelay1[channel] = dataNotch[channel, 749];
}
if (enableNotch)
{
return(new IntanUsbData(dataNotch, auxFrame));
}
else
{
return(new IntanUsbData(dataFrame, auxFrame));
}
}
// public methods
/// <summary>
/// Attempt to open RHA2000-EVAL board connected to USB port.
/// </summary>
/// <param name="firmwareID1">Board ID number (1 of 3)</param>
/// <param name="firmwareID2">Board ID number (2 of 3)</param>
/// <param name="firmwareID3">Board ID number (3 of 3)</param>
public void Open(ref int firmwareID1, ref int firmwareID2, ref int firmwareID3)
{
// Open FTDI USB device.
UInt32 ftdiDeviceCount = 0;
FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK;
// Create new instance of the FTDI device class.
ftdiDeviceA = new FTDI();
// Determine the number of FTDI devices connected to the machine.
ftStatus = ftdiDeviceA.GetNumberOfDevices(ref ftdiDeviceCount);
// Check status.
if (!(ftStatus == FTDI.FT_STATUS.FT_OK))
{
IntanUsbException e = new IntanUsbException("USB Setup Error: Failed to get number devices");
throw e;
}
// If no devices available, return.
if (ftdiDeviceCount == 0)
{
IntanUsbException e = new IntanUsbException("No valid USB devices detected");
throw e;
}
// Allocate storage for device info list.
FTDI.FT_DEVICE_INFO_NODE[] ftdiDeviceList = new FTDI.FT_DEVICE_INFO_NODE[ftdiDeviceCount];
// Populate our device list.
ftStatus = ftdiDeviceA.GetDeviceList(ftdiDeviceList);
// There could be a status error here, but we're not checking for it...
// The Intan Technologies RHA2000-EVAL board uses an FTDI FT2232H chip to provide a USB
// interface to a PC. Detailed information on this chip may be found at:
//
// http://www.ftdichip.com/Products/ICs/FT2232H.htm
//
// The FT2232H supports two independent FIFO channels. The channel used by the RHA2000-EVAL
// board is factory-configured with the name "Intan I/O board 1.0 A". (FTDI provides software
// routines to open device by its name.)
ftStatus = ftdiDeviceA.OpenByDescription("Intan I/O Board 1.0 A");
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Intan USB device A not found");
throw e;
}
// Set read timeout to 5 seconds, write timeout to infinite
ftStatus = ftdiDeviceA.SetTimeouts(5000, 0);
// There could be status error here, but we're not checking for it...
this.Stop();
// Purge receive buffer
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
// Check board ID and version number
//
// The RHA2000-EVAL board is controlled by sending one-byte ASCII command characters over
// the USB interface. The 'I' character commands the board to return a 3-byte ID/version
// number.
UInt32 numBytesWritten = 0;
Byte[] myChars = { 73 }; // 'I' = request board ID and version number
ftStatus = ftdiDeviceA.Write(myChars, 1, ref numBytesWritten);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Could not write to Intan USB device");
throw e;
}
const UInt32 numBytesToRead = 3;
// Wait until the desired number of bytes have been received.
UInt32 numBytesAvailable = 0;
while (numBytesAvailable < numBytesToRead)
{
ftStatus = ftdiDeviceA.GetRxBytesAvailable(ref numBytesAvailable);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("Failed to get number of USB bytes available to read");
throw e;
}
}
// Now that we have the amount of data we want available, read it.
UInt32 numBytesRead = 0;
ftStatus = ftdiDeviceA.Read(readDataBufferA, numBytesToRead, ref numBytesRead);
if (ftStatus != FTDI.FT_STATUS.FT_OK)
{
IntanUsbException e = new IntanUsbException("USB read error");
throw e;
}
firmwareID1 = Convert.ToInt32(readDataBufferA[0]);
firmwareID2 = Convert.ToInt32(readDataBufferA[1]);
firmwareID3 = Convert.ToInt32(readDataBufferA[2]);
Debug.WriteLine("Board ID: " + readDataBufferA[0] + " " + (Convert.ToInt32(readDataBufferA[1])).ToString() + " " + (Convert.ToInt32(readDataBufferA[2])).ToString());
this.ZCheckOff();
this.SettleOff();
// Purge receive buffer.
ftdiDeviceA.Purge(FTDI.FT_PURGE.FT_PURGE_RX);
dataJustStarted = true;
}