User’s Manual U13850EJ4V0UM
106
CHAPTER 4 BUS CONTROL FUNCTION
The V850/SB1 and V850/SB2 are provided with an external bus interface function by which external memories
such as ROM and RAM, and I/O can be connected.
4.1 Features
•
Address bus (capable of separate output)
•
16-bit data bus
•
Able to be connected to external devices via the pins those have alternate-functions as ports
•
Wait function
• Programmable wait function, capable of inserting up to 3 wait states per 2 blocks
• External wait control through WAIT input pin
•
Idle state insertion function
•
Bus mastership arbitration function
•
Bus hold function
4.2 Bus Control Pins and Control Register
4.2.1 Bus control pins
The following pins are used for interfacing to external devices:
Table 4-1. Bus Control Pins
External Bus Interface Function
Corresponding Port (pins)
Address/data bus (AD0 to AD7)
Port 4 (P40 to P47)
Address/data bus (AD8 to AD15)
Port 5 (P50 to P57)
Address bus (A1 to A4)
Port 11 (P110 to P113)
Address bus (A5 to A12)
Port 10 (P100 to P107)
Address bus (A13 to A15)
Port 3 (P34 to P36)
Address bus (A16 to A21)
Port 6 (P60 to P65)
Read/write control (LBEN, UBEN, R/W, DSTB, WRL, WRH, RD)
Port 9 (P90 to P93)
Address strobe (ASTB)
Port 9 (P94)
Bus hold control (HLDRQ, HLDAK)
Port 9 (P95, P96)
External wait control (WAIT)
Port 11 (P110)
The bus interface function of each pin is enabled by specifying the memory expansion mode register (MM) or the
memory address output mode register (MAM). For the details of specifying an operation mode of the external bus
interface, refer to
3.4.6 (1) Memory expansion mode register (MM)
and for
(2) Memory address output mode
register (MAM).
Caution For debugging using the separate bus, refer to the user’s manual of corresponding in-circuit
emulator.
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