H8SSLASH2218 datasheet(561/750 Pages) RENESAS

561 / 750 page

Section 14 Universal Serial Bus (USB)

Rev.6.00 Jun. 03, 2008 Page 513 of 698

REJ09B0074-0600

14.5.6

Bulk-In Transfer (Dual FIFOs) (Endpoint 1)

EP1 has two 64-byte FIFOs, but the user can transmit data and write transmit data without being

aware of this dual-FIFO configuration. However, one data write should be performed for one

FIFO. For example, even if both FIFOs are empty, it is not possible to perform EP1PKTE at one

time after consecutively writing 128 bytes of data. EP1PKTE must be performed for each 64- byte

write.

When transmitting data to the host by bulk-in transfer, first enable the EP1 FIFO empty interrupt

by writing 1 to EP1EMPTYE in UIER1. At first, both EP1 FIFOs are empty, and so an EP1 FIFO

empty interrupt is generated immediately. The data to be transmitted is written to the data register

using this interrupt. After the first transmit data write for one FIFO, the other FIFO is empty, and

so the next transmit data can be written to the other FIFO immediately. When both FIFOs are full,

EP1EMPTY is cleared to 0. If at least one FIFO is empty, UIFR1/EP1EMPTY is set to 1. When

ACK is returned from the host after data transmission is completed, the FIFO used in the data

transmission becomes empty. If the other FIFO contains valid transmit data at this time,

transmission can be continued.

When transmission of all data has been completed, write 0 to UIER1/EP1EMPTYE and disable

EXIRQ0 or EXIRQ1 interrupt requests.

H8S/2218 Scheda tecnica(PDF) 561 Page - Renesas Technology Corp