E1/E20/E2/E2 Lite Additional Document
R20UT1994EJ0900 Rev.9.00
Page 49 of 58
Jan.20.22
3.10
Debug Functions
3.10.1
Stepped Execution
(1) Cautions on using step-in (stepped execution)
The value of some SFRs (special function registers) might remain unchanged while stepping into code. If
the values of the SFRs do not change while stepping into code, operate the microcontroller by
continuously executing the instructions instead of executing them in steps.
Stepping into code: Instructions in the user-created program are executed one by one.
Continuous execution: The user-created program is executed from the current PC value.
(2) Step-in (stepped execution) of division operation (target: device with multiplier and divider/multiply-
accumulator).
When the instruction which sets 1 to bit 0 (DIVST) of multiplication/division control register (MDUC) is
stepped, the division operation is not finished. The stepped execution of the division operation of C
source file is not relevant.
(3) Illegal memory access detection
When the function to detect illegal memory accesses is enabled (IAWCTL.7 = 1) and the following cases
are performed, an internal reset will not occur.
⎯
The stepped execution is performed for an instruction that will generate an illegal memory access.
⎯
The software breakpoint is set at an instruction that will generate an illegal memory access, and then
you execute a program from that point.
(4) Function of RAM guard
When the function of RAM guard is enabled (except IAWCTL.5, 4 = 0, 0), the guarded RAM will be
overwritten when the stepped execution to overwrite the guarded RAM is performed.
The guarded RAM will be overwritten when you overwrite the guarded RAM by using memory panel
during a break.
Note: When a program is continuously executed from an instruction where a software breakpoint has been
set, that instruction itself is handled by stepped execution.
3.10.2
[Go to Here]
If [Go to Here] is selected, the software breakpoints and event breakpoints that have been set so far will be
temporarily invalidated.
3.10.3
Debugging in Standby Mode
The break is an interrupt function of the CPU. Standby mode is released by the break generated by using the
following debugging functions.
<1> Forced break
<2> Stepped execution of the standby instruction (Stops the user program after execution instruction)
<3> Short break generated by the pseudo-RRM function (Break When Readout)
<4> Short break generated by the pseudo-DMM function (Break When Write)
<5> Short break generated by setting a breakpoint while executing the user program
