
CHAPTER 5 BUS CONTROL FUNCTION
Preliminary User’s Manual U17790EJ1V0UD
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5.2
Bus Control Pins
The pins used to connect an external device are listed in the table below.
Table 5-1. Bus Control Pins (Multiplexed Bus)
Bus Control Pin
Alternate-Function Pin
I/O
Function
AD0 to AD15
PDL0 to PDL15
I/O
Address/data bus
A16 to A23
PDH0 to PDH7
Output
Address bus
WAIT
PCM0
Input
External wait control
CLKOUT
PCM1
Output
Internal system clock
WR0, WR1
PCT0, PCT1
Output
Write strobe signal
RD
PCT4
Output
Read strobe signal
ASTB
PCT6
Output
Address strobe signal
HLDRQ
PCM3
Input
HLDAK
PCM2
Output
Bus hold control
CS0 to CS3
PCS0 to PCS3
Output
Chip select
Table 5-2. External Control Pins (Separate Bus)
Bus Control Pin
Alternate-Function Pin
I/O
Function
AD0 to AD15
PDL0 to PDL15
I/O
Data bus
A0 to A15
P90 to P915
Output
Address bus
A16 to A23
PDH0 to PDH7
Output
Address bus
WAIT
PCM0
Input
External wait control
CLKOUT
PCM1
Output
Internal system clock
WR0, WR1
PCT0, PCT1
Output
Write strobe signal
RD
PCT4
Output
Read strobe signal
HLDRQ
PCM3
Input
HLDAK
PCM2
Output
Bus hold control
CS0 to CS3
PCS0 to PCS3
Output
Chip select
5.2.1
Pin status when internal ROM, internal RAM, or on-chip peripheral I/O is accessed
When the internal ROM, internal RAM, or on-chip peripheral I/O are accessed, the status of each pin is as follows.
Table 5-3. Pin Statuses When Internal ROM, Internal RAM, or On-Chip Peripheral I/O Is Accessed
Separate Bus Mode
Multiplexed Bus Mode
Address bus (A23 to A0)
Undefined
Address bus (A23 to A16)
Undefined
Data bus (AD15 to AD0)
Hi-Z
Address/data bus (AD15 to AD0)
Undefined
Control signal
Inactive
Control signal
Inactive
Caution
When a write access is performed to the internal ROM area, address, data, and control signals
are activated in the same way as access to the external memory area.
5.2.2
Pin status in each operation mode
For the pin status of the V850ES/SJ3 in each operation mode, see 2.2 Pin Status.