Even though this architecture is different from the stored program architecture,
the mathematical model of a finite automaton is maintained and a practical PE can be
implemented. Note that PEs without program memories might not correspond to the
conventional definition of a MCU or a MPU in terms of programmability. However,
any user programs can be implemented on this four-layer architecture using high
level and behavioral synthesis tools like CWB. In consequence, practical embedded
processors can be implemented using atomic switches.
The above implementation uses LUTs as a conventional FPGA does, and the
configuration memories are not necessary because atomic switches are a kind of
non-volatile switches [21, 22] to provide programmability without configuration
memories. Both program memories and configuration memories are no longer
needed by using atomic switches and high level behavioral synthesis tools. This
feature is highly suitable for processor elements of device computing layer, because
it can eliminate soft errors encountered in harsh environment. For example, it is
suitable for space system use, because it can avoid soft errors induced by radiation on
orbits in space.
4.2 Discussion of a Design Flow to Design Processor
Elements Using Atomic Switches
We proposed a design flow for designing processor elements (PEs) aiming at
onboard sensor applications by incorporating GPE architecture [2]. The design
flow focuses on sensor unit applications used in harsh environment of outer fields,
because the architecture without volatile program memories is suitable for the
application.
Figure 11 shows the physical image of the design flow. Primitives such as ASIC
block libraries and/or Basic Logic Elements (BLEs) using atomic switches are to be
prepared as an initial configuration. Dedicated functions for a specific application are
synthesized and aggregated in the design flow by exploiting functional
Data paths Finite State Machine
Switch
Arithmetic/Logic unit
Etc.
Rando
m logic
I/O Circuitry
I/O layer
Fine grained
layer
Coarse
grained layer
Switch layer
Fig. 10 Generic Processor
element (GPE) architecture
[2]
Atomic Switch FPGA: Application for IoT Sensing Systems in Space
47
the mathematical model of a finite automaton is maintained and a practical PE can be
implemented. Note that PEs without program memories might not correspond to the
conventional definition of a MCU or a MPU in terms of programmability. However,
any user programs can be implemented on this four-layer architecture using high
level and behavioral synthesis tools like CWB. In consequence, practical embedded
processors can be implemented using atomic switches.
The above implementation uses LUTs as a conventional FPGA does, and the
configuration memories are not necessary because atomic switches are a kind of
non-volatile switches [21, 22] to provide programmability without configuration
memories. Both program memories and configuration memories are no longer
needed by using atomic switches and high level behavioral synthesis tools. This
feature is highly suitable for processor elements of device computing layer, because
it can eliminate soft errors encountered in harsh environment. For example, it is
suitable for space system use, because it can avoid soft errors induced by radiation on
orbits in space.
4.2 Discussion of a Design Flow to Design Processor
Elements Using Atomic Switches
We proposed a design flow for designing processor elements (PEs) aiming at
onboard sensor applications by incorporating GPE architecture [2]. The design
flow focuses on sensor unit applications used in harsh environment of outer fields,
because the architecture without volatile program memories is suitable for the
application.
Figure 11 shows the physical image of the design flow. Primitives such as ASIC
block libraries and/or Basic Logic Elements (BLEs) using atomic switches are to be
prepared as an initial configuration. Dedicated functions for a specific application are
synthesized and aggregated in the design flow by exploiting functional
Data paths Finite State Machine
Switch
Arithmetic/Logic unit
Etc.
Rando
m logic
I/O Circuitry
I/O layer
Fine grained
layer
Coarse
grained layer
Switch layer
Fig. 10 Generic Processor
element (GPE) architecture
[2]
Atomic Switch FPGA: Application for IoT Sensing Systems in Space
47