Cannot Read Bytes from an FTDI Serial I2C to Android Eclipse Java app

Question

I have an FTDI UMFT201XB (I2C serial USB Interface) connected to an android 4.2 tablet through a OTG cable. The FTDI is connected to a PIC MCU. I have run the example TN-147 from FTDI and the device is recognized correctly.

I have modded the TN-147 example to read 12 bytes that the MCU has send to UMFT201XB.

The code is:

public void ReNew() {
        byte [] databuf = new byte[5] ;
        byte [] databuf1 = new byte[20];
        device_time=0;
        databuf1[0]= 0x64;
        databuf1[2]= 0x64;
        databuf[0]= 0x09;


        if(ftdid2xx.createDeviceInfoList(Device_ControlFragmentContext) <= 0)
            return;
        ftDevice = ftdid2xx.openByIndex(Device_ControlFragmentContext, 0);

        if (ftDevice == null) {
            Toast.makeText(Device_ControlFragmentContext, "Not supported device",Toast.LENGTH_SHORT).show();
            } else {
                //ftDevice.setLatencyTimer((byte)240);
                ftDevice.purge((byte) (D2xxManager.FT_PURGE_TX | D2xxManager.FT_PURGE_RX));
                ftDevice.setBitMode((byte)0x33 , (byte)0x20);
                iavailable1 = ftDevice.getQueueStatus();
                ftDevice.write(databuf , 1);
                ftDevice.restartInTask();
                iavailable2 = ftDevice.getQueueStatus();
                lenght_ = ftDevice.read(databuf1,iavailable2);
                iavailable3 = ftDevice.getQueueStatus();
                ftDevice.setBitMode((byte)0x32 , (byte)0x20);
                ftDevice.close();

                device_time=databuf1[0]+databuf1[1]+databuf1[2]+databuf1[3]+databuf1[4]+databuf1[5]+databuf1[6]+databuf1[7]+databuf1[8]+databuf1[9]+databuf1[10]+databuf1[11]+databuf1[12]+databuf1[13]+databuf1[14]+databuf1[16]+databuf1[17]+databuf1[18]+databuf1[15]+databuf1[19];
                DEVICE_TIME.setText(String.valueOf(device_time));
                days_view.setText(String.valueOf(iavailable1));
                hours_view.setText(String.valueOf(iavailable2));
                minutes_view.setText(String.valueOf(iavailable3));
                seconds_view.setText(String.valueOf(lenght_));
                SYSTEM_TIME.setText(String.valueOf(593));
        /////////////////////////////////////////////////////////////////////////////////           
    }
    ftDevice.close();

    }

My problem is that on execution, device_time = 200 (dec), iavailable1 = 00, iavailable2 = 12(Dec), and iavailable3 = 12(Dec).

Obviously, the 200 came from

databuf1[0]= 0x64;
databuf1[2]= 0x64; 

The ftDevice.read(databuf1,iavailable2) does not fetch any bytes to databuf1. And the available bytes remains 12(Dec) (iavailable3 = 12).

Please help.

Answer 1

I had a similar problem. Try moving the read portion to a different thread. It worked for me when I passed the FT_Device to an AsyncTask's doInBackground() method that read in the bytes.