38K2 datasheet(109/358 Pages) RENESAS

109 / 358 page

FUNCTIONAL DESCRIPTION

Rev.2.00

Oct 15, 2006

page 90 of 130

38K2 Group

REJ09B0338-0200

HARDWARE

Multichannel RAM Operation Example

The multichannel RAM operation example is shown below.

This example shows the case that an external MCU uses the

38K2 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.

Fig. 131 Multichannel RAM operation example

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

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