In SX Microcontrollers, SX/B Compiler and SX-Key Tool, wchahla wrote:

Dear All ,
Iam working on the PSC but using the SX 28 MC and SX tech board.

The documentation and code examples for PSC is based on BS2 MC.

To communicate with the PSC and set the position of a servo the documentation states the following :

<B>[2]
Syntax: "!SC" C R pw.LOWBYTE, pw.HIGHBYTE, $0D

Reply: none

C  : is the servo channel

R : is the ramping value .

PW : is the position value.

and the code i used is  :

[/2]SEROUT Sdat, Baud,["!SC", 0, 15, pw.LOWBYTE, pw.HIGHBYTE, CR]


The command string is 8 byte long ending with "CR" .

 

the Baud value is 396 corresponding to speed 2400 which is the defualt for the PSC.

 

The code runs properly in BS2 and the servo responds to position commands.

 

I tried to do this using SX/B and used the following code :

 

PW           VAR  WORD

PSC          PIN  RC.7

ServoCmd  VAR  Byte(8)

idx            VAR Byte

Baud          CON  "T2400"

 

........

........

........

Start:
  ' initialization code here
 INITIALIZE_PSC_CMD


Main:
  ' main code here
  TX_PSC_CMD 
  END

 

 

SUB INITIALIZE_PSC_CMD

      PW = 750  'Center the servo.

      ServoCmd(0)="!"
      ServoCmd(1)="S"
      ServoCmd(2)="C"
      ServoCmd(3)= 0
      ServoCmd(4) = 15 'Ramping value
      ServoCmd(5)= PW_LSB
      ServoCmd(6)= PW_MSB
      ServoCmd(7)=13
 ENDSUB

 
SUB TX_PSC_CMD
    FOR idx = 0 to 7
       SEROUT PSC, Baud, ServoCmd(idx) ' send the command, byte at a time
    NEXT
  
ENDSUB

 

The expected servo never responds to the command , no matter what PW value is used.

 

Appreciate any help.

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