In SX Microcontrollers, SX/B Compiler and SX-Key Tool, p.realacci wrote:

Hello,

I'm having a very strange problem with the SX48.
I'll try to explain what's happening:

The chip is used to control a disc loading robot with two DC motors, one solenoid and four optical sensors.
The program is written in SXB, and uses a small time-based ISR written in assembler.

Here is the description of the problem:

The program uses a subroutine (MoveToPosition_Y) that moves vertically the loading arm until it reaches certain position.
This subroutine calls the "Move_V" subroutine which gives power to the motor and programs a timer in PWM mode for the speed control.
The problem is that "Move_V"  is never called from the MoveToPosition_Y sub.

Using the debugger, I've inserted a break-point in the compiler generated code where the jump to the actual address of Move_V is coded.
I've attached a picture that shows the status of the registers as soon as the break-point pops up.
As you can see, the last executed instruction should be "PAGE 800", but the STATUS register does not have the correct value, and points instead to a wrong page.
As a result, the following jump instruction loads the PC with the wrong address.

The strange thing is that if I insert a NOP at any point in the code before calling the Move_V sub, the program works perfectly.

I'm really getting crazy because I cannot find out the cause of this strange behavior.

I'm using the SX-Key ver. 3.2
SASM DLL ver. 1.51.07
SX-B ver. 1.51.03
SXSim ver. 2.08.05
 

Does anybody have an idea?

I can post the full source code if needed.

 

Thank you.

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