Motorola USB08 - page 66

Designer Reference Manual USB08 Evaluation Board
66 Universal Serial Bus (USB) Interface MOTOROLA
Universal Serial Bu s (USB) Interface
configured as an IN or as an OUT endpoint. The reference design uses
this endpoint as an OUT endpoint, to do data transfers to the MCU.
Table 4-2 provides an overview of the endpoint configuration.
Some adjustments in the control registers of the USB module are
necessary for the configuration of the endpoints. While EP0 is always
active as a control endpoint, the bit ENABLE1 in control register 3
(UCR3) has to be set to activate the endpoint EP1. Likewise, the bit
ENABLE2 has to be set for activation of the endpoint EP2.
However, the activation of the endpoints EP1 and EP2 takes place not
in the initialization routine initUSB(), but only after the devi ce receives a
USB reset.
Table 4-2. MC68HC908JB8 Endpoint Configuratio n
Endpoint Type Direction Function
EP0 Control IN/OUT Device configuration
EP1 Interrupt IN Data transfer to the host
EP2 Interrupt OUT(a)
a. Alternatively as IN configurable, this option is not used here.
Data transfer to the device
Bit 7654321Bit 0
Read: TX1ST 0
OSTALL0 ISTALL0
0
PULLEN ENABLE2 ENABLE1
Write: TX1STR
Reset:00000000
= Unimplemented
Figure 4-2. USB Control Register 3 (UCR3)