CHAPTER 4 BUS CONTROL FUNCTION
User’s Manual U12688EJ4V0UM00
119
4.8
Bus Hold Function
4.8.1 Outline of function
If pins P96 and P97 are specified in the control mode, the HLDAK and HLDRQ functions become valid.
If it is determined that the HLDRQ pin has become active (low level) as a bus acquisition request from another bus
master, the external address/data bus and each strobe pin are shifted to high impedance and released (bus hold
state). If the HLDRQ pin becomes inactive (high level) and the bus acquisition request is canceled, driving of these
pins begins again.
During the bus hold interval, internal operations in the V850E/MS1 continue until there is external memory access.
The bus hold state can be known by the HLDAK pin becoming active (low level).
In a multiprocessor configuration, etc., a system that has multiple bus masters can be configured.
Note that bus hold requests are not received with the following timings.
Caution The HLDRQ function is invalid during the reset period. When the RESET pin and HLDRQ pin are
made active simultaneously, and then the RESET pin is made inactive, the HLDAK pin becomes
active after a one-clock idle cycle has been inserted. Note that for a power-on reset, even if the
RESET pin and HLDRQ pin are made active simultaneously, and then the RESET pin is made
inactive, the HLDAK pin does not become active. When a bus master other than the V850E/MS1
is externally connected, execute arbitration at the moment of power-on using the RESET signal.
State
Data Bus Width
Access Configuration
Timing in Which Bus Hold
Request Will Not Be Received
Word access to even address
Between 1st and 2nd times
Between 1st and 2nd times
Word access to odd address
Between 2nd and 3rd times
16 bits
Halfword access to odd address
Between 1st and 2nd times
Between 1st and 2nd times
Between 2nd and 3rd times
Word access
Between 3rd and 4th times
CPU bus lock
8 bits
Halfword access
Between 1st and 2nd times
Read modify write access to
bit operation instruction
Between read access and write
access
Содержание V850E/MS1 UPD703100
Страница 2: ...User s Manual U12688EJ4V0UM00 2 MEMO ...
Страница 6: ...User s Manual U12688EJ4V0UM00 6 MEMO ...
Страница 8: ...User s Manual U12688EJ4V0UM00 8 MEMO ...
Страница 12: ...User s Manual U12688EJ4V0UM00 12 MEMO ...
Страница 26: ...User s Manual U12688EJ4V0UM00 26 MEMO ...
Страница 68: ...User s Manual U12688EJ4V0UM00 68 MEMO ...
Страница 124: ...User s Manual U12688EJ4V0UM00 124 MEMO ...
Страница 198: ...User s Manual U12688EJ4V0UM00 198 MEMO ...
Страница 230: ...User s Manual U12688EJ4V0UM00 230 MEMO ...
Страница 422: ...User s Manual U12688EJ4V0UM00 422 MEMO ...