7641 datasheet(314/385 Pages) RENESAS

314 / 385 page

Rev.2.00

Aug 28, 2006

page 35 of 108

7641 Group

REJ09B0336-0200

APPENDIX

3.3 Notes on use

•Use the transfer instructions such as LDA and STA to set the registers: USB interrupt status

registers 1, 2 (addresses 005216, 005316); USB endpoint 0 IN control register (address 005916); USB

endpoint x IN control register (address 005916); USB endpoint x OUT control register (address

005A16). Do not use the read-modify-write instructions such as the SEB or the CLB instruction.

When writing to bits shown by Table 32 using the transfer instruction such as LDA or STA, a value

which never affect its bit state is required. Take the following sequence to change these bits

contents:

(1) Store the register contents onto a variable or a data register.

(2) Change the target bit on the variable or the data register. Simultaneously mask the bit so that

its bit state cannot be changed. (See to Table 3.3.1.)

(3) Write the value from the variable or the data register to the register using the transfer instruction

such as LDA or STA.

•To use the AUTO_SET function for an IN transfer when the AUTO_SET bit is set to 1, set the FIFO

to single buffer mode.

Table 3.3.1 Bits of which state might be changed owing to software write

USB endpoint 0 IN control register

USB endpoint x (x = 1 to 4) IN control register

USB endpoint x (x = 1 to 4) OUT control register

Bit name

IN_PKT_RDY (b1)

DATA_END (b3)

FORCE_STALL (b4)

IN_PKT_RDY (b0)

UNDER_RUN (b1)

OUT_PKT_RDY (b0)

OVER_RUN (b1)

FORCE_STALL (b4)

DATA_ERR (b5)

Value not affecting state (Note)

“0”

“1”

“0”

“1”

Note: Writing this value will not change the bit state, because this value cannot be written to the bit by software.

(6) Others

•When the USB SOF Port Select Bit is “1”, the reference pulse of 83.3 ns (

φ = 12 MHz) is output

from the P70/SOF pin and synchronized with the SOF packet.

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