Thats okay
It might not even be a serial/TTL connection but more than often when you see a stray chip with so few pins it's serves one of three purposes.
1) USB Controller
2) Serial/TTL buffer (chip that cleans up all the voltages for communications with external devices)
3) General power regulator/buffer (chip that cleans up, steps up or down the voltage a bit to get juice from a battery)
In the HH5 case, I believe that the USB is directly rigged to the main chip, so it's probably TTL :-/
*shrug*
I might bother to get one when I'm bored of getting loads of free devices from all over the show