NEC VR4181 mPD30181, Руководство пользователя

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CHAPTER 1 INTRODUCTION
User’s Manual U14272EJ3V0UM
32
1.3.3 Memory interface
The V
R
4181 provides control for both ROM/flash memory and DRAM. Up to four 16-bit ROM/flash memory banks
may be supported utilizing either 32-Mbit or 64-Mbit single cycle or page mode devices. Bank mixing is not supported
for ROM/flash memory. When a system implements less than the maximum 4 banks of ROM/flash memory, unused
ROM chip select pins can be defined as general-purpose I/O pins.
The V
R
4181 also supports up to 2 banks of 1M x 16 or 4M x 16 EDO-type DRAM or SDRAM at bus frequencies of
up to 66 MHz. When both banks are EDO-type DRAM, bank mixing is supported.
1.3.4 DMA controller (DCU)
The V
R
4181 provides a 4-channel DMA controller to support internal DMA transfers. The 4 channels are allocated
as follows:
•
Channel 1 - Audio input
•
Channel 2 - Audio output
•
Channel 3, 4 - Reserved
1.3.5 Interrupt controller (ICU)
The V
R
4181 provides an interrupt controller which combines all interrupt request sources into one of the V
R
4110
core interrupt inputs - NMI and Int(2:0). The interrupt controller also provides interrupt request status reporting.
1.3.6 Real-time clock
The V
R
4181 includes a real-time clock (RTC), which allows time keeping based on the 32.768 kHz clock as a
source. The RTC operates as long as the V
R
4181 remains powered.
1.3.7 Audio output (D/A converter)
The V
R
4181 provides a 1-channel 10-bit D/A converter for generating audio output.
1.3.8 Touch panel interface and audio input (A/D converter)
The V
R
4181 provides an 8-channel 10-bit A/D converter for interfacing to a touch panel, an external microphone,
and other types of analog input.
1.3.9 CompactFlash interface (ECU)
The V
R
4181 provides an ExCA-compatible bus controller supporting a single CompactFlash slot. This interface is
shared with the keyboard interface logic and must be disabled when an 8 x 8 key matrix is connected to the V
R
4181.
1.3.10 Serial interface channel 1 (SIU1)
The V
R
4181 provides a 16550 UART for implementing an RS-232-C type serial interface. When the serial
interface is not needed, each of the 7 serial interface pins can be individually redefined as general-purpose I/O pins.
1.3.11 Serial interface channel 2 (SIU2)
The serial interface channel 2 is also based on a 16550 UART but only reserves 2 pins for the interface. The serial
interface channel 2 can be configured in one of the following modes:
•
Simple 2-wire serial interface using TxD2 and RxD2
•
SIR-type IrDA interface using IRDIN and IRDOUT
•
Full RS-232-C compatible interface using TxD2, RxD2 and 5 GPIO pins