Here’s a new chip from FTDI which brings a nice little feature to the USB-to-serial converter family: charging detection. That means that it is capable of detecting when a battery charger is connected. What does that actually mean? The top of the datasheet gives you the short version, but let’s look at the investigation [Baoshi] undertook to test the full extent of this particular feature. We agree with him that the listed capability leaves those in the know with a lot of questions:
USB Battery Charger Detection. Allows for USB peripheral devices to detect the presence of a higher power source to enable improved charging.
Obviously the chip will be able to tell when a charger is connected, alerting the device when it’s time to start lapping up the extra milliamps. But what type of chargers will actually trigger the detection circuit? After rigging up the test circuit shown above he ran through several scenarios: connected directly to the PC USB port, via externally powered and non-powered USB hubs, and with multiple wall wart chargers. Full results of the tests are included in the post linked above.
[via Dangerous Prototypes]
[Hans Peter] wanted to move away from using full Arduino boards in his projects. One of the components he rarely used after the development stage is the USB hardware. Once the firmware is flashed to the chip he didn’t need it any longer. So he tried his hand with some really small SMD parts by building this USB to serial Arduino programmer.
The chip he went with isn’t the FTDI part we’re used to. Instead of using an FT232RL, he opted for its smaller cousin the FT230x. This chip doesn’t fully implement the communications protocol of the 232, but it does work with AVRdude and that’s all that really matters. Above you can see [Hans'] creation next to the official Arduino USB-to-serial programmer. He used the same connection scheme, but went with an edge connector for the USB instead of using a mini-B jack.
It’s pretty impressive to see his prototyping work with the 16-pin QFN package. He soldered it dead-bug style to a couple of SIL pin headers in order to test it on a breadboard. The first board he assembled was too loose in the USB port, but he added some tape to the back to make it thicker, and coated the edge connector traces with a bit of solder and that did the trick.