LR4102 datasheet(3/32 Pages) LSI

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TinyRISC LR4102 Microprocessor

Block Diagram

This section provides short descriptions of the major components of the

LR4102, as shown in Figure 1.

The CPU performs all arithmetic, logical, shift, and address calculations.

The CPU supports EJTAG debug and is closely coupled with the

FastMDU. The FastMDU calculates all multiply and divide operations for

the LR4102, and provides 4/5 cycle multiply and accumulate operations

(32 bit to 64 bit), 34/35 cycle divide, saturated math, and overﬂow

indication.

The memory management unit (MMU) translates virtual addresses from

the CPU into physical addresses and includes a 64-entry translation

look-aside buffer (TLB) RAM.

The BIU and cache controller (BBCC) provides an internal bus interface

and connects the CPU to the caches. For the caches, the LR4102

contains 16 Kbytes of two-way set-associative I-Cache and 8 Kbytes of

direct-mapped D-Cache. Four Write Buffers are integrated with the

BBCC in the LR4102 design.

The 32-bit FBusMACRO (FBM) controls the FBus, a dedicated,

multimaster bus that connects off-chip logic with the LR4102. The FBus

allows seamless LR4102 connection to a variety of devices, including

EPROM, FLASH, RAM, DRAM, SDRAM, and general-purpose I/O pins.

The FBus also supports burst read (one cycle) and write, built-in

arbitration for an external FBus master, and snooping of external write

accesses to memory. Internally, the FBusMACRO interfaces mainly with

the BBCC module.

Each 32-bit Timer can count down from a preloaded value, roll over or

stop at zero, generate an interrupt on zero, or act as bus watchdog. The

CPU can program either of the two internal 32-bit timers.

The LR4102 includes 1 Kbyte of on-chip memory (OCM).

The Clock Controller steps CPU clock speed up or down, and can stop

the internal LR4102 clock altogether. The LR4102 also supports a low

power mode. The LR4102 Clock Controller is designed to support a

crystal or canned oscillator, and has an on-chip PLL for frequency

multiplication.

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