h8s-2158 Renesas Electronics Corporation., h8s-2158 Datasheet - Page 219

• Manufacturer Part Number: h8s-2158
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

This LSI incorporates a RAM-FIFO unit (RFU). The RFU is activated by a request from the
peripheral modules and can transfer data between the peripheral modules and on-chip RAM. As
the RFU can specify the RAM address to be transferred by using a pointer that is updated for
every data transfer execution, the RAM specified area can be regarded as an FIFO. If an FIFO
full/empty or overrun error occurs according to pointer update, the RFU can acknowledge this
error to the peripheral modules. The peripheral modules request pointer reset and manipulation of
the temporary pointer in addition to data transfer.
A block diagram of the RFU is shown in figure 8.1.
8.1
RAMFU00A_000020020300
Bus master with priority higher than that of the CPU and DTC
Provides the RFU-ID to specific peripheral modules (SCI, USB, and MCIF) to specify the
peripheral modules to be manipulated by the RFU with ID numbers
RFU bus cycle accesses the peripheral modules and on-chip RAM simultaneously
During an RFU bus cycle, the address bus outputs a RAM address for data transfer
RAM address for data transfer is specified by the on-chip pointer set of the RFU
Four pointer sets
The contents of the pointer set are updated for every data transfer, and a specific RAM area
can be manipulated as the FIFO (RAM-FIFO)
RAM-FIFO size: 32/64/128/256/512/1024/2048 bytes selectable
An interrupt can be generated by a RAM-FIFO full/empty or overrun error
RFU operates in high-speed mode even when the LSI is in medium-speed mode
Features
Section 8 RAM-FIFO Unit (RFU)
Rev. 3.00 Jan 25, 2006 page 167 of 872
Section 8 RAM-FIFO Unit (RFU)
REJ09B0286-0300