Rev. 1.0, 03/01, page
32
of
280
2.6
Basic Bus Cycle
CPU operation is synchronized by a system clock (ø) or a subclock (ø
SUB
). The period from a rising
edge of ø or ø
SUB
to the next rising edge is called one state. A bus cycle consists of two states or
three states. The cycle differs depending on whether access is to on-chip memory or to on-chip
peripheral modules.
2.6.1
Access to On-Chip Memory (RAM, ROM)
Access to on-chip memory takes place in two states. The data bus width is 16 bits, allowing access
in byte or word size. Figure 2-9 shows the on-chip memory access cycle.
T
1
state
Bus cycle
T
2
state
Internal address bus
Internal read signal
Internal data bus
(read access)
Internal write signal
Read data
Address
Write data
Internal data bus
(write access)
SUB
ø or ø
Figure 2-9 On-Chip Memory Access Cycle
Summary of Contents for H8/3670F-ZTAT HD64F3670
Page 2: ...Rev 2 0 03 01 page ii of xxiv ...
Page 4: ...Rev 2 0 03 01 page iv of xxiv ...
Page 14: ...Rev 2 0 03 01 page xiv of xxiv ...
Page 20: ...Rev 1 0 03 01 page xx of xxiv ...
Page 24: ...Rev 1 0 03 01 page xxiv of xxiv ...
Page 78: ...Rev 1 0 03 01 page 54 of 280 ...
Page 112: ...Rev 1 0 03 01 page 88 of 280 ...
Page 248: ...Rev 1 0 03 01 page 224 of 280 ...