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transfer instructions. To write 7-byte data correctly, data must be written once by a longword
transfer instruction, once by a word transfer instruction, and once by a byte transfer instruction, or
data must be written three times by a word transfer instruction and once by a byte transfer
instruction.
To read data from the USB endpoint data register (UEDRno) on the receive side, the correct size
of data must be read. In this case, the data size is specified by the USB endpoint receive size data
register (UESZno).
To execute DMA transfer on data in the USB endpoint data register using the on-chip DMAC,
byte transfer musts be used. In word transfer, odd-byte data cannot be transferred. Word transfer is
thus disabled.
15.9.12 Restrictions for Software Standby Mode Transition
Before entering the software standby mode, disabled the SOF marker function and set the USB
module stop state as shown in figure 15.13. The UDC core must not be reset.
To access the USB module after software standby mode, cancel the USB module stop state and
wait for the USB operating clock (48 MHz) stabilization time as shown in figure 15.33.
Rev. 3.0, 10/02, page 530 of 686
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