38K2 Datasheet, PDF (89/151 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K2 Group
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.
CPU
Program ROM
➂ Activating
➁ Notice of receive completion
External MCU bus
External bus interface
Multichannel RAM
Peripheral functions
USB
➃ FIFO read of received data
by External bus interface
➀ FIFO write of received data
by USB
USB bus
(USB host)
Fig. 131 Multichannel RAM operation example
Rev.3.00 Oct 15, 2006 page 89 of 147
REJ03B0193-0300