ADUC7122 Analog Devices, ADUC7122 Datasheet - Page 40

• Manufacturer Part Number: ADUC7122
• Description: Precision Analog Microcontroller, 12-Bit Analog I/O, ARM7TDMI® MCU
• Manufacturer: Analog Devices

Specifications of ADUC7122

• Mcu Core: ARM7 TDMI
• Mcu Speed (mips): 40
• Sram (bytes): 8192Bytes
• Gpio Pins: 32
• Adc # Channels: 13

ADuC7122
Table 57. FEE0PRO and FEE0HID MMR Bit Designations
Bit
31
30:0
Table 58. FEE1PRO and FEE1HID MMR Bit Designations
Bit
31
30
29:0
EXECUTION TIME FROM SRAM AND FLASH/EE
This section describes SRAM and Flash/EE access times during
execution of applications where execution time is critical.
Execution from SRAM
Fetching instructions from SRAM takes one clock cycle because
the access time of the SRAM is 2 ns and a clock cycle is 22 ns
minimum. However, if the instruction involves reading or
writing data to memory, one extra cycle must be added if the
data is in SRAM (or three cycles if the data is in Flash/EE), one
cycle to execute the instruction and two cycles to obtain the
32-bit data from Flash/EE. A control flow instruction, such as a
branch instruction, takes one cycle to fetch, but it also takes
two cycles to fill the pipeline with the new instructions.
Execution from Flash/EE
Because the Flash/EE width is 16 bits and access time for 16-bit
words is 23 ns, execution from Flash/EE cannot be completed in
one cycle (contrary to a SRAM fetch, which can be completed in
a single cycle when CD bits = 0). Dependent on the instruction,
some dead times may be required before accessing data for any
value of CD bits.
In ARM mode, where instructions are 32 bits, two cycles are
needed to fetch any instruction when CD = 0. In Thumb mode,
where instructions are 16 bits, one cycle is needed to fetch any
instruction.
Description
Read protection.
Cleared by the user to protect Block 0.
Set by the user to allow reading of Block 0.
Write protection for Page 123 to Page 120, for Page 119 to Page 116, and for Page 3 to Page 0.
Cleared by the user to protect the pages in writing.
Set by the user to allow writing the pages.
Description
Read protection.
Cleared by the user to protect Block 1.
Set by the user to allow reading of Block 1.
Write protection for Page 127 to Page 120.
Cleared by the user to protect the pages in writing.
Set by the user to allow writing the pages.
Write protection for Page 119 to Page 116 and for Page 3 to Page 0.
Cleared by the user to protect the pages in writing.
Set by the user to allow writing the pages.
Rev. 0 | Page 40 of 96
Timing is identical in both modes when executing instructions
that involve using Flash/EE for data memory. If the instruction
to be executed is a control flow instruction, an extra cycle is
needed to decode the new address of the program counter and
then four cycles are needed to fill the pipeline. A data processing
instruction involving only core registers does not require any
extra clock cycles, but if it involves data in Flash/EE, an extra
clock cycle is needed to decode the address of the data and two
cycles to obtain the 32-bit data from Flash/EE. An extra cycle
must also be added before fetching another instruction. Data
transfer instructions are more complex and are summarized in
Table 59.
Table 59. Execution Cycles in ARM/Thumb Mode
Instructions
LD
LDH
LDM/PUSH
STR
STRH
STRM/POP
With 1 < N ≤ 16, N is the number of bytes of data to load or
store in the multiple load/store instruction. The SWAP instruction
combines an LD and STR instruction with only one fetch,
giving a total of eight cycles plus 40 μs.
Fetch
Cycles
2/1
2/1
2/1
2/1
2/1
2/1
Dead
Time
1
1
N
1
1
N
Data Access
2
1
2 × N
2 × 20 μs
20 μs
2 × N × 20 μs
Dead
Time
1
1
N
1
1
N