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RX850

FAQ-ID : v85rx-nnnn

0001	RX850 Pro interrupts [RX850 Pro]
0002	RX850 handler [RX850 Pro]
0003	Reduction of task stack area
0004	Start address of RX850 Pro
0005	Saving of ISP
0006	OS debugging method
0007	Usage of area acquired with get_blk
0008	DI processing in the OS
0009	The RX850 stops.
0010	PSW ID flag control
0011	Task priority
0012	System clock processing call
0013	Sample program
0014	Warning W2215 caused by "undeclared function call" option
0015	Distance between interrupt table and OS jump destination
0016	TCP/IP support for RTOS
0017	V850 TRON
0018	Differences between the RX850 and RX850 Pro
0019	RX850 Pro support

RX850 Pro interrupts [RX850 Pro]

FAQ-ID : v85rx-0001

Q-1: Is it possible that OS processing will be executed during maskable interrupt servicing?

A-1: Unless a system call is issued, OS processing will not be executed during maskable interrupt servicing.

RX850 handler [RX850 Pro]

FAQ-ID : v85rx-0002

Q-1: How long does it take from the occurrence of a RX850 hardware interrupt source until the startup of the interrupt handler.
The CPU is the V850/SA1 (17MHz).

A-1: The interrupt handler startup time for the V850E/MS1 (25MHz operation) with internal ROM/RAM was 2.7 to 2.9μs.
Since these CPUs have the same architecture, convert the operating frequency to obtain the desired number.
This is an actually measured value and thus should be used carefully.

Reduction of task stack area

FAQ-ID : v85rx-0003

Q-1: The stack size of each task is specified in the configuration file.
Is it possible to release the stack area of a non-operating task for another task stack?
Or must the stack be secured continuously and independently regardless of the operating state of each task?

A-1: Basically, it must be secured for each task.
We are not sure what you mean by the operating state of each task but for a task in the sleep state, the stack is used to retain that status.

In the RX850, if tasks that do not operate at the same time are grouped together, the stack area can be reduced.
In this case, the user must manage tasks carefully (ensure that these tasks do not operate at the same time).

(Refer to 3.2, "Task Execution Right" in the Basics User's Manual.)

Q-2: The size of "intstk" is specified in the configuration file.
Is this stack only used for the interrupt handler?

A-2: This is used for the interrupt handler and timer handler.

Start address of RX850 Pro

FAQ-ID : v85rx-0004

Q-1: Is it necessary to make the start address a multiple of 4 to link the RX850 Pro?
Are there any other limitations?

A-1: As long as the start address is multiple of 4, it is OK.
There are no other limitations.

Saving of ISP

FAQ-ID : v85rx-0005

Q-1: I'm using the GHS compiler.
The contents of ISP (r2) differ from the expected value in the OS and the OS jumps to an unexpected location.
ISP seems not to be saved within the OS.
Are there any cautions pertaining to compiling and linking I should be aware of?

A-1: r2 and r5 cannot be used when using the GHS compiler.
Specify the -reserve_r2 and -reserve_r5 options.

OS debugging method

FAQ-ID : v85rx-0006

Q-1: Even if there is enough space available, when get_blk is executed, the system enters the wait status.
Is there any way of analyzing the cause of this?

A-1: Use the task debugger (RD850 Pro) in a case like this.
You can check the wait status of the memory pool using the RD850 Pro.

Usage of area acquired with get_blk

FAQ-ID : v85rx-0007

Q-1: Are the first 4 bytes of an area acquired with get_blk user-accessible? When data is written to the start address, the area cannot be released using rel_blk.

A-1: It is OK to use from the start of a memory block but you have to clear the first 4 bytes of the memory block to zero when you release the memory block.
From RX850 Pro V3.15, some libraries do not require the first 4 bytes to be cleared.

DI processing in the OS

FAQ-ID : v85rx-0008

Q-1: Is there any processing other than using the clock handler to perform DI, such as using an OS system call?
In this case, how many clocks does it take to perform DI ?

A-1: DI processing is performed in various places within the OS such as task scheduling.
However, it is generally expressed in units of time limited to the CPU and operating clock (not calculated by the number of clocks).

The RX850 stops.

FAQ-ID : v85rx-0009

Q-1: Control shifts to the initial block of the nucleus and the HALT status is entered.
Are there any conditions under which this will happen other than memory shortage?

A-1: The OS enters the HALT status when a management table cannot be created for some reason, rather than due to memory shortage.
In addition, check to make sure there is no program lockup or memory error.

PSW ID flag control

FAQ-ID : v85rx-0010

Q-1: Can PSW ID flag control be performed by the user?
Is a system call provided to operate the PSW ID flag?

A-1: This is managed by the OS. Do not manipulate this within the OS.

Task priority

FAQ-ID : v85rx-0011

Q-1: Which has the higher priority, task 0x01 or task 0x02 ?

A-1: The smaller the value, the higher the priority (0x01 is higher in this case).

System clock processing call

FAQ-ID : v85rx-0012

Q-1: How is system clock processing called?

A-1: System clock processing starts when a clock interrupt is generated.
That is, it is handled as an indirectly started interrupt handler.

Sample program

FAQ-ID : v85rx-0013

Q-1: What does a sample program do?

A-1: Four tasks are created and they execute timeout waiting, resource waiting (semaphore, event flag waiting) and resource capture.
Refer to task.c where task1 to task4 are described.
We are sure this will help you understand the program.

Q-2: Does the sample program run on a standalone PC ?

A-2: No, it cannot be executed as is.
If a simulator is also running on the PC, the program runs as well.
Otherwise, it cannot be operated on a standalone PC.

Warning W2215 caused by "undeclared function call" option

FAQ-ID : v85rx-0014

Q-1: If "Undeclared function call" is checked using a compiler option specification,

"Warning: W2215: Undeclared function '*****' is called"

is output in response to an OS (RX850 Pro) system call or _rcopy().

A-1: For RX850 Pro system calls, include stdrx85p.h.
The _rcopy function is not a system call and thus describe a prototype declaration in the source data as follows:

int _rcopy(unsigned long *,long);

Distance between interrupt table and OS jump destination

FAQ-ID : v85rx-0015

Q-1: Is it possible to jump even if the distance between the interrupt table (V850: starting from address 0) and the OS object is 0x1FFFFF or more?

A-1: If the distance assigned is 0x1FFFFF or more, branch cannot be performed.
Make sure that the distance is within the range that can be branched with jr.

In addition, when using the device address wraparound, an address branched from a negative direction such as address FFFFE000 instead of address 3FFE000 can be considered.
(Address FFFFE000 is simply the higher address set as 1 and thus another value is required in an actual case.)

TCP/IP support for RTOS

FAQ-ID : v85rx-0016

Q-1: Do RTOS (uITRON standard) products include a TCP/IP protocol stack area?

A-1: The V850 Series supports TCP/IP (product name: AP703100-B17).
The following third-party products are also provided:

- AI Corporation
- ACCESS CO., LTD.
- Aplix Corporation
- Elmic Systems Inc.

V850 TRON

FAQ-ID : v85rx-0017

Q-1: Can RTOS : pSOS or μITRON be mounted on the V850 ?

A-1

Our product RX850 conforms to μITRON3.
In addition, regarding pSOS, a product that supports the V850E is available from a third-party company.

Contact the following company for details:


Integrated Systems Japan
TEL	: 03-3492-3171
FAX	: 03-3492-3066
E-mail	: info@isi.co.jp
HP	: http://www.isi.com/

Differences between the RX850 and RX850 Pro

FAQ-ID : v85rx-0018

Q-1: The RX850 is available in two types: the RX850 and the RX850 Pro.
What are the differences between the RX850 and RX850 Pro?