DLP2010NIR: Connect to Android smartphone via USB

Benjamin Zaiser

Part Number: DLP2010NIR

I have implemented an Android app which communicates with the DLP NIRscan Nano via Bluetooth LE. It is working fine, but unfortunately it takes a long time to transfer the scan results - especially if you want to do several individual scans in a row.

That's why I'm currently trying to connect the device via an USB OTG cable to the Android smartphone. I can successfully connect to the device via USB but it is unclear how to read or write data.

What I have understood so far:

the device provides two endpoints: one with IN direction and one with OUT direction.
both endpoints have interrupt type, that's why I need to communicate asynchronously (see https://developer.android.com/reference/android/hardware/usb/UsbRequest.html) by using queue() and requestWait() methods.
based on the documentation the device is using HID 1.1 to exchange commands. An example project would be the Missile Launcher: https://github.com/aosp-mirror/platform_development/blob/master/samples/USB/MissileLauncher/src/com/android/missilelauncher/MissileLauncherActivity.java which is using
- UsbRequest#queue()
- sendCommand() which is calling mConnection.controlTransfer(0x21, 0x9, 0x200, 0, message, message.length, 0);
- requestWait() to wait until a response is available. But this is not working as well. Also changing the sendCommand to int transfer = mConnectionRead.controlTransfer(0xA1, 0x01, 0x00, 0x01, message, message.length, 0); doesn't work (transfer = -1), see Using Android to Communicate with a USB HID Device

When I want to read e.g. the Tiva version information, I thought it will work like the code mentioned below. The specification of the device: http://www.ti.com/lit/ug/dlpu030g/dlpu030g.pdf see page 83

Why is it not working? I never get any response from the sensor.

Do I have to use controlTransfer? Is the data packet wrong? Is it possible at all to connect the scanner via USB to an Android smartphone?

Any help appreciated :-)

Thanks Ben

Looks like there is a bug in this board, because I cannot add my source code.
You can find the source code here: https://stackoverflow.com/questions/49748315/ti-dlp-nirscan-nano-connect-to-android-smartphone-via-usb

over 6 years ago

0 Sreeram Subramanian over 6 years ago

TI__Prodigy 575 points

Hi Ben,
In the ByteBuffer (data) you are passing to request.queue(), make the first byte as 0 followed by the bytes you want to send. The first byte is the report number that is needed by the Windows/Linux drivers. This byte is consumed by the driver and not sent to the device. Please let us know if this resolves the issue you are facing.

Best Regards,
Sreeram

0 Benjamin Zaiser over 6 years ago in reply to Sreeram Subramanian

Prodigy 20 points

Hi Sreeram,

Thanks for your info. In the UsbPacket#toByteArray() method (see https://stackoverflow.com/questions/49748315/ti-dlp-nirscan-nano-connect-to-android-smartphone-via-usb) I'm already setting the first byte as 0x00, see

byte[] header = new byte[] {
                0x00,
                flags,
                (byte) sequence,
                dataLength[0],
                dataLength[1],
                commandByte,
                groupByte
        };

Also tried to set it like this:

byte[] header = new byte[] {
                0x00,
                0x00,
                flags,
                (byte) sequence,
                dataLength[0],
                dataLength[1],
                commandByte,
                groupByte
        };

But it is still not sending any response :-(

Thanks
Ben

0 Sreeram Subramanian over 6 years ago in reply to Benjamin Zaiser

TI__Prodigy 575 points

Ah I see.
Is it possible that your dataLength{0] and [1] bytes are sent in the reverse order or the CommandByte and GroupByte also going in the reverse order? The best way would be to compare the byte traffic from Windows application and Linux application with a USB analyzer if you have one.

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DLP2010NIR: Connect to Android smartphone via USB