MC9S08JM16 Datasheet, PDF (307/386 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Device Controller (S08USBV1)
Table 17-12. ERRSTAT Field Descriptions (continued)
Field
1
CRC5
0
PIDERR
Description
CRC5 Interrupt Enable — Setting this bit will enable CRC5 interrupts.
0 Interrupt disabled
1 Interrupt enabled
PIDERR Interrupt Enable — Setting this bit will enable PIDERR interrupts.
0 Interrupt disabled
1 Interrupt enabled
17.3.9 Status Register (STAT)
The STAT reports the transaction status within the USB module. When the MCU receives a TOKDNE
interrupt, the STAT is read to determine the status of the previous endpoint communication. The data in
the status register is valid only when the TOKDNEF interrupt flag is asserted. The STAT register is actually
a read window into a status FIFO maintained by the USB module. When the USB module uses a BD, it
updates the status register. If another USB transaction is performed before the TOKDNE interrupt is
serviced, the USB module will store the status of the next transaction in the STAT FIFO. Thus, the STAT
register is actually a four byte FIFO which allows the microcontroller to process one transaction while the
serial interface engine (SIE) is processing the next. Clearing the TOKDNEF bit in the INTSTAT register
causes the SIE to update the STAT register with the contents of the next STAT value. If the next data in the
STAT FIFO holding register is valid, the SIE will immediately reassert the TOKDNE interrupt.
7
6
5
4
3
2
1
0
R
ENDP[3:0]
IN
ODD
0
0
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 17-12. Status Register (STAT)
Table 17-13. STAT Field Descriptions
Field
Description
7–4
ENDP[3:0]
Endpoint Number — These four bits encode the endpoint address that received or transmitted the previous
token. This allows the microcontroller to determine which BDT entry was updated by the last USB transaction.
0000 Endpoint 0
0001 Endpoint 1
0010 Endpoint 2
0011 Endpoint 3
0100 Endpoint 4
0101 Endpoint 5
0110 Endpoint 6
MC9S08JM16 Series Data Sheet, Rev. 2
Freescale Semiconductor
307