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2.6.2
Access to On-Chip Peripheral Modules
On-chip peripheral modules are accessed in two states or three states. The data bus width is 8 bits,
so access is by byte size only. This means that for accessing word data, two instructions must be
used.
Two-state access to on-chip peripheral modules
Figure 2.12 shows operation timings for accessing on-chip peripheral modules in 2 states.
T
1
state
Bus cycle
T
2
state
ø or ø
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
Figure 2.12 On-Chip Peripheral Module Access Cycle (2-State Access)
Three-state access to on-chip peripheral modules
Figure 2.13 shows operation timings for accessing on-chip peripheral modules in 3 states.