adviceLUNA / TRQer Support
What is the adaptive clock? How RTCK signal is used?
[Question]
What is the adaptive clock?
What kind of signal is RTCK?
[Answer]
Adaptive clocking mode (adaptive clock) is a function to dynamically follow the JTAG communication frequency of ICE in accordance with the operating frequency of target MPU when the ICE is connected to ARM core.
It is mainly used for MPU(ASIC) using ARM software macro-core.
In many cases, ARM software macro-core MPU which uses adaptive clocking mode latches TCK input signal from JTAG-ICE at 2 or 3 flip-flop on the system clock internally. It outputs the latch output signal to pin as RTCK.
For TCK signals sent from ICE, ICE detects the responses of RTCK and send next TCK (communication data). Therefore there is an advantage that it can communicate with JTAG-ICE with maximum JTAG clock frequency at that time by using an adaptive clocking mode if the systems whose internal clock of target MPU is changed dynamically.
RTCK responses for TCK are much quickly and the communication speed is improved as the operation frequency of target MPU is larger.
If you do not use the adaptive clock, JTAG clock frequency which can be communicated at when the target CPU operation is slowest is adopted by ICE. Therefore the performance of ICE does not improve even if the operation frequency of target MPU is larger.
It also send data by using JTAG clock frequency of ICE regardless of the operation frequency of target MPU. Therefore the reliability may be not higher than when using the adaptive clocking mode (Error may occur).
What is the adaptive clock?
What kind of signal is RTCK?
[Answer]
Adaptive clocking mode (adaptive clock) is a function to dynamically follow the JTAG communication frequency of ICE in accordance with the operating frequency of target MPU when the ICE is connected to ARM core.
It is mainly used for MPU(ASIC) using ARM software macro-core.
In many cases, ARM software macro-core MPU which uses adaptive clocking mode latches TCK input signal from JTAG-ICE at 2 or 3 flip-flop on the system clock internally. It outputs the latch output signal to pin as RTCK.
For TCK signals sent from ICE, ICE detects the responses of RTCK and send next TCK (communication data). Therefore there is an advantage that it can communicate with JTAG-ICE with maximum JTAG clock frequency at that time by using an adaptive clocking mode if the systems whose internal clock of target MPU is changed dynamically.
RTCK responses for TCK are much quickly and the communication speed is improved as the operation frequency of target MPU is larger.
If you do not use the adaptive clock, JTAG clock frequency which can be communicated at when the target CPU operation is slowest is adopted by ICE. Therefore the performance of ICE does not improve even if the operation frequency of target MPU is larger.
It also send data by using JTAG clock frequency of ICE regardless of the operation frequency of target MPU. Therefore the reliability may be not higher than when using the adaptive clocking mode (Error may occur).
Please cooperate with the questionnaire
Was this answer stood to the visitor's role?