Renesas HEW Target Register Operation Limitations, Stop or Wait Mode Limitations, Register Name

7.4. Register Operation Limitations

Table 6-2 lists the limitations on register operation. The registers are inhibited from any modification. If register contents are modified in any way, kernel operation cannot be guaranteed.

Table 7-2: Limitations on Register Operation

Register Name	Restriction
User and Interrupt Stack Pointers	RAM memory range 0B80H – 0BFFH is used by
	the kernel. Do not set stacks in this area.
UART1 Transmit/Receive Mode Register	Do not change.
UART1 Transmit/Receive Control Register 0
UART1 Transmit/Receive Control Register 1
UART1 Interrupt Control Register 0	Do not change.
UART Transmit/Receive Control Register 2	Do not change bits 0 and 2.
UART1 Transmit Buffer Register	Do not write to this register.
UART1 Receive Buffer Register	Do not read this register.
Port 6 and Port 6 DDR	To prevent changes on P6_4 data and direction,
	use read-modify-write only instructions (BSET,
	BCLR, AND, OR, etc.).

7.5. Limitations on Interrupts – Vectors that Reside in the Hardware Vector Table

Table 7-3lists the limitations on hardware interrupt (i.e. fixed) vector addresses.

Table 7-3: Interrupt Vector Addresses

Interrupt Cause	M16C/26A Vector Address	Kit Specification
Undefined	FFFDCh ~ FFFDFh	User available
Overflow	FFFE0h ~ FFFE3h	User available
BRK Instruction	FFFE4h ~ FFFE7h	User inhibited
Address Match	FFFE8h ~ FFFEBh	User inhibited
Single-step	FFFECh ~ FFFEFh	User inhibited
Watchdog Timer	FFFF0h ~ FFFF3h	User available (Note 1)
DBC	FFFF4h ~ FFFF7h	User inhibited
NMI	FFFF8h ~ FFFFBh	User available
RESET	FFFFCh ~ FFFFFh	Reset vector (Note 2)

NOTES:

(1)The Watchdog Timer vector is shared with the oscillation stop and voltage detection interrupts. The vector is available for oscillation stop and voltage detection interrupts, but you must avoid using the vector for watchdog timer interrupts.

(2)The kernel transparently relocates the Reset vector to FFFD8h.

7.6.Stop or Wait Mode Limitations

The kernel cannot be run in STOP or WAIT modes. Do not use these modes when debugging your program.

7.7. User Program’s Real-Time Capability (Very Important – Please Read)

Please be aware that while the kernel is in a “STOP” state, the hardware peripherals will continue to run. Therefore, interrupts may not be serviced properly. In addition, the watchdog timer will not be serviced and will likely time out if active.

HTS Demo Kit V1.0 12/ 20 December 2007