UPD70732 datasheet(21/66 Pages) NEC

21 / 66 page

µPD70732

BUS INTERFACE FUNCTION

The V810 is equipped with a 32-bit data bus.

In the bus interface, there are two modes: 32-bit bus mode which uses the data bus in 32 bits and 16-bit bus

fixed mode which fixes the bus in 16 bits. Modes can be switched only at reset using the SIZ16B signal.

The 32-bit bus mode has a dynamic bus sizing function which uses the data bus in 16-bit bus width to access

the 16-bit peripherals. This function can be used by setting the SZRQ signal active. Access to word data

(32-bit data) in the dynamic bus sizing is executed by loading/storing a 16-bit data twice.

In the 16-bit bus fixed mode, access to word data (32-bit data) is executed by activating a bus cycle twice.

The control signal and the A1 signal output values according to the 16-bit system.

The relationship between the external access and byte enable signals (BE3 to BE0) during the 32-bit bus mode

and the 16-bit bus fixed mode is shown below.

Table 5-1. Relationship among Address, Data Length, Byte Enable Signals and A1

(32-bit bus mode)

Operand address

Byte enable

Bit 1

Bit 0

BE3

BE2

BE1

BE0

Byte

011

101

011

110

111

Halfword

100

011

Word

011

2Note

Note

Bus cycle added by dynamic bus sizing

Table 5-2. Relationship among Address, Data Length, Byte Enable Signals and A1

(16-bit bus fixed mode)

Operand address

Byte enable

Bit 1

Bit 0

BE3

BE2

BE1

BE0

Byte

Hi-Z

Halfword

Hi-Z

Word

Hi-Z

2Note

Note

Added bus cycle

Data length

Bus cycle

sequence

Data length

Bus cycle

sequence

UPD70732 Datasheet(PDF) 21 Page - NEC

UPD70732 Datasheet(HTML) 21 Page - NEC

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66

Datasheet Download

Link URL