Cypress EZ-USB Series 2100 - Manual (Page 5)

EZ-USB Series 2100
Enumeration and
ReNumeration
Anchor Chips’ proprietary
ReNumeration™ function is the
means by which the enhanced
8051 firmware is downloaded.
How It Works
Upon power-up or plug-in, the
EZ-USB chip automatically
enumerates as a default USB
device. This allows the USB core
to download 8051 code. The USB
core logic inside EZ-USB per-
forms this initial enumeration
and code download while holding
the 8051 in reset.
Once enumerated, the host PC
downloads 8051 code into
EZ-USB RAM over the USB
interface. (Anchor Chips supplies
the software tools to incorporate
the loader into any application).
The downloaded 8051 code
contains program, data, and
enumeration tables. Once loaded,
the EZ-USB core performs a
ReNumeration cycle to simulate a
USB disconnect and reconnect to
come back as a completely new
USB device.
This entire sequence of enumera-
tion, download and ReNum-
eration happens quickly (less
than a quarter of a second) and is
transparent to the user.