Usb Command Register (Uscom) - Freescale Semiconductor MPC850 User Manual

USB Registers
Table 32-9 describes the USEPn fields.
Bits Name
0–3 EPN Endpoint number. Defines the supported endpoint number assigned by the external host. Applies
only in slave mode; it is ignored in host mode.
4–5 — Reserved, should be cleared.
6–7 TM Transfer mode
00 Control
01 Interrupt
10 Bulk
11 Isochronous
8–9 — Reserved, should be cleared.
10 MF Enable multiframe. Allows loading of the next transmit packet into the FIFO before the previous
packet finishes transmitting. Should be cleared unless the endpoint is configured for isochronous
transfers or is configured as a host (endpoint 0 only).
0 The transmit FIFO may hold only one packet.
1 The transmit FIFO may hold more than one packet.
11 RTE Retransmit enable. Should be cleared for endpoints configured for isochronous transfers.
0 No retransmission.
1 Enable automatic frame retransmission. Frame is retransmitted if a transmit error occurs (time-out).
Note: May be set only if the transmit packet is contained in a single buffer. Otherwise, retransmission
should be handled by software intervention.
12– THS Transmit handshake. Applies in slave mode only.
13 00 Normal handshake.
01 Ignore IN token.
10 Force NAK handshake. Not allowed for control endpoint.
11 Force STALL handshake. Not allowed for control endpoint.
14– RHS Receive handshake. Applies in slave mode only.
15 00 Normal handshake.
01 Ignore OUT token.
10 Force NAK handshake. Not allowed for control endpoint.
11 Force STALL handshake. Not allowed for control endpoint.

32.7.4 USB Command Register (USCOM)

The USB command (USCOM) register, shown in Figure 32-10, is used to start USB
transmit operation.
Bit 0
Field STR
Reset
R/W
Addr
Figure 32-10. USB Command Register (USCOM)
Table 32-9. USEPn Field Descriptions
1 2
FLUSH
MPC850 Family User's Manual
Description
3 4
—
0000_0000
R/W
0xA02
5 6
EP
7