Product manual

Spinpoint M9TU-USB 3.0 Product Manual REV 1.0
41
USB INTERFACE AND USB COMMANDS
Table 6-3: PID Types
PIDs are divided into four coding groups: token, data, handshake, and special, with the first two transmitted
PID bits (PID<0:1>) indicating which group. This accounts for the distribution of PID codes.
6.3.2.3 Address Fields
Function endpoints are addressed using two fields: the function address field and the endpoint field. A function
needs to fully decode both address and endpoint fields. Address or endpoint aliasing is not permitted, and a
mismatch on either field must cause the token to be ignored. Accesses to non-initialized
The function address (ADDR) field specifies the function, via its address, that is either the source or destination
of a data packet, depending on the value of the token PID. As shown in Figure 6-15, a total of 128 addresses are
specified as ADDR<6:0>. The ADDR field is specified for IN, SETUP, and OUT tokens and the PING and
SPLIT special token. By definition, each ADDR value defines a single function. Upon reset and power-up, a
function’s address defaults to a value of zero and must be programmed by the host during the enumeration
process. Function address zero is reserved as the default address and may not be assigned to any other use.
Figure 6-15: ADDR Field