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custom baud rates for PL2303TA/TB
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see https://lore.kernel.org/r/[email protected]
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@kai-morich
kai-morich committed May 11, 2021
1 parent 22a685e commit 2f23bdf
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Showing 4 changed files with 58 additions and 34 deletions.
6 changes: 4 additions & 2 deletions usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java
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Expand Up @@ -26,6 +26,7 @@
import com.hoho.android.usbserial.driver.FtdiSerialDriver;
import com.hoho.android.usbserial.driver.ProbeTable;
import com.hoho.android.usbserial.driver.ProlificSerialDriver;
import com.hoho.android.usbserial.driver.ProlificWrapper;
import com.hoho.android.usbserial.driver.SerialTimeoutException;
import com.hoho.android.usbserial.driver.UsbId;
import com.hoho.android.usbserial.driver.UsbSerialDriver;
Expand Down Expand Up @@ -323,11 +324,12 @@ public void prolificBaudRate() throws Exception {
};
usb.open();

int minBaudRate = ProlificWrapper.isDeviceTypeT(usb.serialPort) ? 6 : 46;
try {
usb.setParameters(45, 8, 1, UsbSerialPort.PARITY_NONE);
usb.setParameters(minBaudRate-1, 8, 1, UsbSerialPort.PARITY_NONE);
fail("baud rate to low expected");
} catch(UnsupportedOperationException ignored) {}
usb.setParameters(46, 8, 1, UsbSerialPort.PARITY_NONE);
usb.setParameters(minBaudRate, 8, 1, UsbSerialPort.PARITY_NONE);
usb.setParameters(384_000_000, 8, 1, UsbSerialPort.PARITY_NONE);
try {
usb.setParameters(384_000_001, 8, 1, UsbSerialPort.PARITY_NONE);
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8 changes: 8 additions & 0 deletions ...ialForAndroid/src/androidTest/java/com/hoho/android/usbserial/driver/ProlificWrapper.java
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@@ -0,0 +1,8 @@
package com.hoho.android.usbserial.driver;

public class ProlificWrapper {
public static boolean isDeviceTypeT(UsbSerialPort serialPort) {
ProlificSerialDriver.ProlificSerialPort prolificSerialPort = (ProlificSerialDriver.ProlificSerialPort) serialPort;
return prolificSerialPort.mDeviceType == ProlificSerialDriver.DeviceType.DEVICE_TYPE_T;
}
}
1 change: 0 additions & 1 deletion usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/util/UsbWrapper.java
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Expand Up @@ -21,7 +21,6 @@
import java.util.EnumSet;
import java.util.LinkedList;
import java.util.concurrent.Callable;
import java.util.concurrent.Executors;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
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77 changes: 46 additions & 31 deletions ...erialForAndroid/src/main/java/com/hoho/android/usbserial/driver/ProlificSerialDriver.java
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Expand Up @@ -35,7 +35,7 @@ public class ProlificSerialDriver implements UsbSerialDriver {
28800, 38400, 57600, 115200, 128000, 134400, 161280, 201600, 230400, 268800,
403200, 460800, 614400, 806400, 921600, 1228800, 2457600, 3000000, 6000000
};
private enum DeviceType { DEVICE_TYPE_01, DEVICE_TYPE_HX}
protected enum DeviceType { DEVICE_TYPE_01, DEVICE_TYPE_T, DEVICE_TYPE_HX}

private final UsbDevice mDevice;
private final UsbSerialPort mPort;
Expand Down Expand Up @@ -98,7 +98,7 @@ class ProlificSerialPort extends CommonUsbSerialPort {
private static final int STATUS_BUFFER_SIZE = 10;
private static final int STATUS_BYTE_IDX = 8;

private DeviceType mDeviceType = DeviceType.DEVICE_TYPE_HX;
protected DeviceType mDeviceType = DeviceType.DEVICE_TYPE_HX;
private UsbEndpoint mInterruptEndpoint;
private int mControlLinesValue = 0;
private int mBaudRate = -1, mDataBits = -1, mStopBits = -1, mParity = -1;
Expand Down Expand Up @@ -163,7 +163,7 @@ private void doBlackMagic() throws IOException {
vendorIn(0x8383, 0, 1);
vendorOut(0, 1, null);
vendorOut(1, 0, null);
vendorOut(2, (mDeviceType == DeviceType.DEVICE_TYPE_HX) ? 0x44 : 0x24, null);
vendorOut(2, (mDeviceType == DeviceType.DEVICE_TYPE_01) ? 0x24 : 0x44, null);
}

private void setControlLines(int newControlLinesValue) throws IOException {
Expand Down Expand Up @@ -253,25 +253,21 @@ public void openInt(UsbDeviceConnection connection) throws IOException {
}
}

if (mDevice.getDeviceClass() == 0x02) {
byte[] rawDescriptors = connection.getRawDescriptors();
if(rawDescriptors == null || rawDescriptors.length < 14) {
throw new IOException("Could not get device descriptors");
}
int usbVersion = (rawDescriptors[3] << 8) + rawDescriptors[2];
int deviceVersion = (rawDescriptors[13] << 8) + rawDescriptors[12];
byte maxPacketSize0 = rawDescriptors[7];
if (mDevice.getDeviceClass() == 0x02 || maxPacketSize0 != 64) {
mDeviceType = DeviceType.DEVICE_TYPE_01;
} else if(deviceVersion == 0x300 && usbVersion == 0x200) {
mDeviceType = DeviceType.DEVICE_TYPE_T; // TA
} else if(deviceVersion == 0x500) {
mDeviceType = DeviceType.DEVICE_TYPE_T; // TB
} else {
byte[] rawDescriptors = connection.getRawDescriptors();
if(rawDescriptors == null || rawDescriptors.length <8) {
Log.w(TAG, "Could not get device descriptors, Assuming that it is a HX device");
mDeviceType = DeviceType.DEVICE_TYPE_HX;
} else {
byte maxPacketSize0 = rawDescriptors[7];
if (maxPacketSize0 == 64) {
mDeviceType = DeviceType.DEVICE_TYPE_HX;
} else if ((mDevice.getDeviceClass() == 0x00)
|| (mDevice.getDeviceClass() == 0xff)) {
mDeviceType = DeviceType.DEVICE_TYPE_01;
} else {
Log.w(TAG, "Could not detect PL2303 subtype, Assuming that it is a HX device");
mDeviceType = DeviceType.DEVICE_TYPE_HX;
}
}
mDeviceType = DeviceType.DEVICE_TYPE_HX;
}
setControlLines(mControlLinesValue);
resetDevice();
Expand Down Expand Up @@ -315,34 +311,53 @@ private int filterBaudRate(int baudRate) {
}
/*
* Formula taken from Linux + FreeBSD.
*
* For TA+TB devices
* baudrate = baseline / (mantissa * 2^exponent)
* where
* mantissa = buf[10:0]
* exponent = buf[15:13 16]
*
* For other devices
* baudrate = baseline / (mantissa * 4^exponent)
* where
* mantissa = buf[8:0]
* exponent = buf[11:9]
*
* Note: The formula does not work for all PL2303 variants.
* Ok for PL2303HX. Not ok for PL2303TA. Other variants unknown.
*/
int baseline, mantissa, exponent;
int baseline, mantissa, exponent, buf, effectiveBaudRate;
baseline = 12000000 * 32;
mantissa = baseline / baudRate;
if (mantissa == 0) { // > unrealistic 384 MBaud
throw new UnsupportedOperationException("Baud rate to high");
}
exponent = 0;
while (mantissa >= 512) {
if (exponent < 7) {
mantissa >>= 2; /* divide by 4 */
exponent++;
} else { // < 45.8 baud
throw new UnsupportedOperationException("Baud rate to low");
if (mDeviceType == DeviceType.DEVICE_TYPE_T) {
while (mantissa >= 2048) {
if (exponent < 15) {
mantissa >>= 1; /* divide by 2 */
exponent++;
} else { // < 7 baud
throw new UnsupportedOperationException("Baud rate to low");
}
}
buf = mantissa + ((exponent & ~1) << 12) + ((exponent & 1) << 16) + (1 << 31);
effectiveBaudRate = (baseline / mantissa) >> exponent;
} else {
while (mantissa >= 512) {
if (exponent < 7) {
mantissa >>= 2; /* divide by 4 */
exponent++;
} else { // < 45.8 baud
throw new UnsupportedOperationException("Baud rate to low");
}
}
buf = mantissa + (exponent << 9) + (1 << 31);
effectiveBaudRate = (baseline / mantissa) >> (exponent << 1);
}
int effectiveBaudRate = (baseline / mantissa) >> (exponent << 1);
double baudRateError = Math.abs(1.0 - (effectiveBaudRate / (double)baudRate));
if(baudRateError >= 0.031) // > unrealistic 11.6 Mbaud
throw new UnsupportedOperationException(String.format("Baud rate deviation %.1f%% is higher than allowed 3%%", baudRateError*100));
int buf = mantissa + (exponent<<9) + (1<<31);

Log.d(TAG, String.format("baud rate=%d, effective=%d, error=%.1f%%, value=0x%08x, mantissa=%d, exponent=%d",
baudRate, effectiveBaudRate, baudRateError*100, buf, mantissa, exponent));
Expand Down

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