Today some small news and infos about driving the Logitech G19 display stand-alone, some explanations about the Futaba MDM166A warning and an update of the XML Library. First of all, let’s start with the Logitech G19 display. I got one without the keyboard and started to get it running without the keyboard and USB hub. It is quite easy, as the display itself is just an slave device of the built in USB hub. The following picture shows the backside of the display PCB including the connector J11 on the left side.
The pinout of the connector J11
|1||Shield||shield of the USB cable|
|2||+5 V||5 V power supply (100 mA)|
|4||D+||USB Data +|
|6||D-||USB Data -|
|7||+3.3 V||3.3 V power supply (250 mA)|
The only difficulty is to get an additional 3.3 V power source. In the original keyboard, this supply was generated on the USB hub PCB, but I do not need it. So I just took an 3.3 fixed voltage LDO by ST (LD1117Axx33) as I got them nearby. The display PCB draws just about 200 mA current, so the voltage regulator was even getting warm in its DPAK case (without cooling – free wired). The 5 V power supply line draws up to 100 mA. I will not answer the question about driving the whole display over the USB. I think you should decide by yourself, as the USB host just draws about 100 mA to an unidentified device and I have not yet looked at the device descriptor about the requested current draw.
This takes me to the next issue of this post: the Futaba MDM166A. Some people misunderstood my last warning about the display. So I have to clarify some things:
1. The display itself is not defective, the is properly designed and still fully functional. The warning has nothing todo with a construction mistake or similar.
2. The display is anytime safe to use, when connecting USB (CN1) and another 5V power supply (CN2). For example: use it, as it was designed for: connect the USB connector (CN1) to your USB host device and connect the floppy power connector (CN2) to the computers power supply. Another possibility is to use an external 5 V power supply and connect it to the floppy power connector (CN2), when no computer power supply is available at the place of use.
3. You can connect the display just to one USB port with the delivered cable, but this is done at your own risk! The load is too heavy on startup and so it is not recommend. But yes, up to now, there is no damage to any USB host known. (This information was supplied by the german seller of these displays).
Summary: You can connect the display to just one USB host port, but at your own risk!. I am not responsible for any damage it may lead to.
And now coming to the last issue of this post, I have updated the XMLLib to version 1.104. The changes include some bug fixes on loading from empty streams, a wrong parameter decoration on TXMLNodeList.Delete() and adding the possibility to move an XML node to another position in the structure. The last change can be achieved by setting the parent property of the node or using the new Move() method. Warning: both ways do not check the target node, to be an sub node of the actual node to move. So you can get endless recursions! The actual version can be found at the project page as usual.