Fujitsu MB96300 series Hardware Manual page 311

MB96300 Super Series Hardware Manual
Bit name
bit [5:0] EAE[5:0]:
External area enable
bit 6 ERE: External ROM
enable
bit 7 NMS:
Non-multiplexed bus
mode
In External Vector mode, this register is configured by automatically reading the External bus mode byte
(after reading the Boot Vector) externally from address FFFFDF
Chapter 12.5 "External Boot Vector fetch" for more information).
The External bus mode register can be rewritten by software at any time.
If the MCU starts in Internal Vector mode, this register keeps its default values.
• The EAE (External Area Enable) bits are used to activate the External address
areas
• '0' - the corresponding external address area is disabled. All other settings for
this area have no effect.
• '1' - the corresponding external address area is enabled. The setting of the
corresponding EACH/EACL and EAS registers define the characteristics of the
address area. Configure these registers before setting the EAE bit to '1'.
• External ROM can only be used if an external area is enabled accordingly.
• The initial value of EAE[5:0] bits is '0'.
• Before the external Boot Vector fetch EAE[5] is set to '1', (except
MB96(F)38x for startup in non-multiplexed bus mode where EAE[4] is set to
'1'.
• After the Boot Vector fetch, the EBM register is overwritten by the externally
read External bus mode byte. See also Chapter 12.5 "External Boot Vector
fetch".
• This bit selects if the internal ROM is accessed or an external access is
performed for the address area of the internal ROM
• '0' - the internal ROM (Flash) is accessed (Internal ROM mode)
• '1' - the access is redirected to the external bus (External ROM mode)
• An external bus access is performed only if an external address area is activated
with the EAE bit which includes the address of the current access.
• The initial value is '0'. During external Boot Vector fetch, this bit is set to '1'.
After the external Boot Vector fetch, the EBM register is overwritten by the
externally read External bus mode byte. See also Chapter 12.5 "External Boot
Vector fetch".
• This bit selects the non-multiplexed or multiplexed bus mode for all external
areas.
• '0' - selects multiplexed bus mode for all external areas
• '1' - selects non-multiplexed bus mode for all external areas
• It depends on the device which modes are available.
• The initial value is '0'. During external Boot Vector fetch, this bit is set
according to the access mode selected by the mode pins MD[2:0]. After the
Boot Vector fetch, the EBM register is overwritten by the externally read
External bus mode byte. See also Chapter 12.5 "External Boot Vector fetch".
CHAPTER 12 EXTERNAL BUS INTERFACE
Function
and writing the data to the register (see
H
303