38K0 datasheet(89/328 Pages) RENESAS

89 / 328 page

FUNCTIONAL DESCRIPTION

Rev.2.00

Oct 05, 2006

page 72 of 112

38K0 Group

REJ09B0337-0200

HARDWARE

Multichannel RAM Operation Example

The multichannel RAM operation example is shown below.

This example shows the case that an external MCU uses the

38K0 group as a peripheral LSI (USB controller).

The following explains that the external MCU reads out the data

which is received via the USB.

➀ The data which is received via the USB is written into the multi-

channel RAM.

➁ Receive completion is propagated to the CPU.

➂ The external bus interface is activated owing to the CPU.

➃ (1) The external bus interface sets the data which is read from

the multichannel RAM into the internal data buffer.

(2) The external MCU reads out the data bus buffer of the exter-

nal bus interface.

(3) The above operation is repeated by the number of the re-

ceived bytes. After that, the data transfer is completed.

CPU

USB

External MCU bus

USB bus

(USB host)

Program ROM

Peripheral functions

External bus interface

Multichannel RAM

➂ Activating

➃ FIFO read of received data

by External bus interface

➀ FIFO write of received data

by USB

➁ Notice of receive completion

Fig. 101 Multichannel RAM operation example

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