USBB17RX78K4-XXX NEC Electronics, USBB17RX78K4-XXX Datasheet - Page 88

• Manufacturer Part Number: USBB17RX78K4-XXX
• Description: 78K/4 series realtime OS
• Manufacturer: NEC Electronics

memory pool, and cyclic handler) in 256 bytes of the internal RAM area 0F700H through 0F7FFH. However, the area
of 14 bytes starting from 0F700H is an OS management area. Each object management area is secured from there
on. Then the 6 bytes to 32 bytes ready queue area is secured. The ready queue area varies depending on the
specified number of task priorities. Each object can be generated in up to 255 units.
RAM size used
RAM size used
On RX78K/IV, it is possible to set an area capable of generating objects (TCB, event flag, semaphore, mail box,
Calculation of the object size (data) for a system running RX78K/IV is shown below.
Example Where number of objects to be created is:
154 (bytes)
Total
94 (bytes)
p
p
=
=
APPENDIX 6
Task
Semaphore
Cyclic handler : 2
Memory pool
The task priority can be used up to 10 levels.
The top address (?objhead) of the OS management area shall be 0F700H.
OS
management
table
2 ò 10 u 3
14
p
ò
Memory pool
: 20
: 4
: 2 (number of memory blocks: 5, size of 1 memory block: 10 bytes)
ESTIMATING MEMORY CAPACITY (SMALL MODEL)
Ready
queue
2 u 10
(number of memory blocks: 10, size of 1 memory block: 6 bytes)
p
p
ò
154 ò 94 = 248 (bytes)
ò
2 ò 6 u 10
8 u 10
TCB
Event flag : 5
Mail box
p
ò
Event flag
: 3
2 u 5
p
ò
Semaphore
2 u 4
p
ò
Mail box
2 u 3
p
ò
Cyclic
handler
8 u 2
p
79