■ DESCRIPTION
The MB91101 and MB91101A are a standard single-chip microcontroller constructed around the 32-bit RISC CPU (FR* family) core with abundant I/O resources and bus control functions optimized for high-performance/high-speed CPU processing for embedded controller applications. To support the vast memory space accessed by the 32-bit CPU, the MB91101 and MB91101A normally operate in the external bus access mode and executes instructions on the internal 1 Kbyte cache memory and 2 Kbytes RAM for enhanced performance.
The MB91101 and MB91101A are optimized for applications requiring high-performance CPU processing such as navigation systems, high-performance FAXs and printer controllers.

■ FEATURES
FR CPU
• 32-bit RISC, load/store architecture, 5-stage pipeline
• Operating clock frequency: Internal 50 MHz/external 25 MHz
   (PLL used at source oscillation 12.5 MHz)
• General purpose registers: 32 bits × 16
• 16-bit fixed length instructions (basic instructions), 1 instruction/1 cycle
• Memory to memory transfer, bit processing, barrel shifter processing:
   Optimized for embedded applications
• Function entrance/exit instructions, multiple load/store instructions of
   register contents, instruction systems supporting high level languages
• Register interlock functions, efficient assembly language coding
• Branch instructions with delay slots: Reduced overhead time in branch executions
• Internal multiplier/supported at instruction level
   Signed 32-bit multiplication: 5 cycles
   Signed 16-bit multiplication: 3 cycles
• Interrupt (push PC and PS): 6 cycles, 16 priority levels

External bus interface
• Clock doubler: Internal 50 MHz, external bus 25 MHz operation
• 25-bit address bus (32 Mbytes memory space)
• 8/16-bit data bus
• Basic external bus cycle: 2 clock cycles
• Chip select outputs for setting down to a minimum memory block size of 64 Kbytes: 6
• Interface supported for various memory technologies
   DRAM interface (area 4 and 5)
• Automatic wait cycle insertion: Flexible setting, from 0 to 7 for each area
• Unused data/address pins can be configured as input/output ports.
• Little endian mode supported (Select 1 area from area 1 to 5)

DRAM interface
• 2 banks independent control (area 4 and 5)
• Normal mode (double CAS DRAM)/high-speed page mode (single CAS DRAM)/Hyper DRAM
• Basic bus cycle: Normally 5 cycles, 2-cycle access possible in high-speed page mode
• Programmable waveform: Automatic 1-cycle wait insertion to RAS and CAS cycles
• DRAM refresh
   CBR refresh (interval time configurable by 6-bit timer)
   Self-refresh mode
• Supports 8/9/10/12-bit column address width
• 2CAS/1WE, 2WE/1CAS selective

Cache memory
• 1-Kbyte instruction cache memory
• 32 block/way, 4 entry(4 word)/block
• 2 way set associative
• Lock function: For specific program code to be resident in cashe memory

DMA controller (DMAC)
• 8 channels
• Transfer incident/external pins/internal resource interrupt requests
• Transfer sequence: Step transfer/block transfer/burst transfer/continuous transfer
• Transfer data length: 8 bits/16 bits/32 bits selective
• NMI/interrupt request enables temporary stop operation.

UART
• 3 independent channels
• Full-duplex double buffer
• Data length: 7 bits to 9 bits (non-parity), 6 bits to 8 bits (parity)
• Asynchronous (start-stop system), CLK-synchronized communication selective
• Multi-processor mode
• Internal 16-bit timer (U-TIMER) operating as a proprietary baud rate generator: Generates any given baud rate
• External clock can be used as a transfer clock.
• Error detection: Parity, frame, overrun
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