Fujitsu F2MC-16LX Hardware Manual page 322

16-bit microcontroller mb90330 series

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CHAPTER 13 USB FUNCTION

In both OUT- direction and IN- direction transfer, a USB device must perform processes in the following

1. It sets the total number of pieces of data to be transferred in the data counter register DDCT in DMA

and enables DMA with the DER register.

2. DMAE and DRQIE, are permitting set.

3. Once transfer has been completed, it sets µDMAC again with an interrupt due to the corresponding

interrupt factor in the DSR register of µDMAC and clear the flag if necessary, and returns from the

interrupt process.

*:EP1 to EP5 consists of the double buffers, it can be cleared only when one buffer that is not being

accessed is empty and data is read from another buffer being accessed (Automatic clear) and cannot be

cleared if one buffer that is not being accessed has data left to be read. It continuously enters the DRQ

interrupt process.

Figure 13.4-11 OUT Direction (Host PC → Device) Forwarding

Last OUT packet

Read PKS part of

DMA receive buffer

Read the rest of

DMA receive buffer