Renesas RL78/D1A - Securing a Stack Area for Debugging

E1/E20/E2/E2 Lite Additional Document 3. Notes on Usage
R20UT1994EJ0910 Rev.9.10 Page 42 of 59
Oct.06.23
3.3.2 Securing a Stack Area for Debugging
The debugger requires 4 bytes as a stack area for debugging except if start/stop functions (only supported
by the E2/E2 Lite) are in use, in which case the size of the stack area for debugging is up to 8 bytes. Since
this area is allocated immediately below the main stack area, the address of this area varies with increases
and decreases in the stack size. That is, if a program is using none of the stack (the stack is empty), the 4- or
8-byte stack area for the debugger remains.
Make sure the stack area for debugging does not go beyond the range of the internal RAM space.*
1
When a monitoring point (extended function of the E2) is in use, the size of the stack area for debugging is 6
bytes.
Figure 3-3 to Figure 3-5 show examples in which the stack area has increased with the start address of the
internal RAM space being 0xFCF00.
Stack area for
debugging
4 bytes or 12 bytes
Stack area
Available space
in internal RAM
0xFCF00
0xFFEDF
Stack area for
debugging
4 bytes or 12 bytes
Stack area
Available space
in internal RAM
0xFCF00
0xFFEDF
Stack area for
debugging
4 bytes or 12 bytes
Stack area
0xFFEDF
0xFCF00
Figure 3-3 Variation of Address of Stack Area for Debugging (E1/E20)
Stack area
Available space
in internal RAM
0xFCF00
Stack area for
debugging
4 bytes, 8 bytes, or
12 bytes
0xFFEDF
Stack area
Available space
in internal RAM
0xFCF00
0xFFEDF
Stack area
0xFCF00
0xFFEDF
Stack area for
debugging
4 bytes, 8 bytes, or
12 bytes
Stack area for
debugging
4 bytes, 8 bytes, or
12 bytes
Figure 3-4 Variation of Address of Stack Area for Debugging (E2 Lite)
Stack area
Available space
in internal RAM
0xFCF00
Stack area for
debugging
4 bytes, 6 bytes,
8 bytes, or 12 bytes
0xFFEDF
Stack area
Available space
in internal RAM
0xFCF00
0xFFEDF
Stack area
0xFCF00
0xFFEDF
Stack area for
debugging
4 bytes, 6 bytes,
8 bytes, or 12 bytes
Stack area for
debugging
4 bytes, 6 bytes,
8 bytes, or 12 bytes
Figure 3-5 Variation of Address of Stack Area for Debugging (E2)
*1 During self-programming, the size of the stack area for debugging is up to 12 bytes.
Refer to the self-programming manual for how to secure the stack area for self programming.
The start/stop function is disabled for self-programming.