174
CHAPTER 7 MODE SETTING
7.5.3
Hold function
This section uses timing charts to describe the operation of the hold function.
■
Operation of hold function
When the HDE bit of EPCR is set to "1", the external bus hold function specified by both the
P54/HRQ and P55/HAK pins becomes effective. When the "H" level is input to the P54/HRQ
pin, the hold state is set upon completion of a command by the CPU (after data of 1 element is
processed in the case of the string command), and the "L" level is output from P55/HAK to set
the following pins to a high-impedance state:
❍
Non-multiplex mode
•
Address output: A23 to A00
•
Data input/output: D15/AD15 to D00/AD00
•
Bus control signal: P51/RD, P52/WRL, P53/WRH
❍
Multiplex mode
•
Address output: A23 to A16
•
Address output, Data input/output: D15/AD15 to D00/AD00
•
Bus control signal: P51/RD, P52/WRL, P53/WRH
This operation enables use of the external bus via the device external circuit. When the "L" level
is input to the P54/HRQ pin, the P55/HAK pin outputs the "H" level to restore the external pin
state, and the CPU restarts operation. In the STOP state, requests for hold are rejected.
Summary of Contents for MB90480 Series
Page 2: ......
Page 4: ......
Page 10: ...vi ...
Page 128: ...106 CHAPTER 4 RESET ...
Page 174: ...152 CHAPTER 6 LOW POWER CONSUMPTION MODE ...
Page 198: ...176 CHAPTER 7 MODE SETTING ...
Page 220: ...198 CHAPTER 9 TIMEBASE TIMER ...
Page 238: ...216 CHAPTER 11 WATCH TIMER ...
Page 280: ...258 CHAPTER 12 16 BIT INPUT OUTPUT TIMER ...
Page 406: ...384 CHAPTER 17 8 10 BIT A D CONVERTER ...
Page 478: ...456 CHAPTER 20 CHIP SELECTION FACILITY ...
Page 494: ...472 CHAPTER 21 ADDRESS MATCH DETECTION FUNCTION ...
Page 498: ...476 CHAPTER 22 ROM MIRROR FUNCTION SELECTION MODULE ...
Page 526: ...504 CHAPTER 23 2M 3M BIT FLASH MEMORY ...
Page 536: ...514 CHAPTER 24 EXAMPLES OF MB90F481B MB90F482B MB90F488B MB90F489B SERIAL PROGRAMMING ...
Page 570: ...548 CHAPTER 25 PWC TIMER ONLY MB90485 SERIES ...
Page 688: ......