potreadd.asm

主要是8051源代码

;  PotReadd - Read the Pot Values and Send to the Servos  
;
;  This Application Reads Resistance Values by Allowing a Capacitor 
;   Wired to a Pot to Charge and then Measure the Time the Cap takes
;   To Discharge.
;
;  Two AT89C2051 pins are used for reading each Pot.  
;
;  The values of each Pot are sent to the Servo Controller at 1200 bps 
;   using a simple Transmission Protocol.   
;
;  Myke Predko
;  98.05.16
;
;  Hardware Notes:
;  89C2051 Running at 10 MHz
;  P1.6 is Connected to the Elevator R/C Charge/Discharge Circuit
;  P1.7 is Connected to the Aileron R/C Charge/Discharge Circuit
;  P1.0 is Connected to the R/C Voltage which is the Pulse State
;   Between the Capacitor and Resistor for the Elevator
;  P1.1 is Connected to the R/C Voltage which is the Pulse State
;   Between the Capacitor and Resistor for the Aileron
;  P3.1 is used to Send Data Serially to the Servo AT89C2051.
;  P3.0 is used to Receive Data Serially from the Servo AT89C2051


;  Variable Declarations
;  R0 - R2: Delay Counter Variables
;  R3: Elevator Value
;  R4: Aileron value 


 org 0

  mov    SCON,#%01010000        ;  Serial Port in Mode 1
  mov    TMOD,#%00100000        ;  Put Timer1 in Mode 2
  mov    TH1,#234
  mov    TL1,#234
  setb   TCON.6                 ;  Start the Timer Running

Mainline:                       ;  Program Mainline

  mov    P1,#%00111111          ;  Allow the Capacitors to Discharge

  mov    R3,#0                  ;  Clear the Elevator Counter
  mov    R4,#0                  ;  Clear the Aileron Counter

  clr    RI                     ;  Clear the Serial Data Receive Bit

  mov    R0,#0FFh               ;  Let the Cap Discharge
  mov    R1,#010h               ;  For 10 msecs
Loop1:
  djnz   R0,Loop1
  djnz   R1,Loop1

  mov    P1,#%01111111          ;  Now, Wait for the Elevator Capacitor to Charge

Loop2:                          ;  Loop Until the the Line Becomes High
  inc    R3                     ;  Increment the Elevator Position Counter
  jnb    P1.0,Loop2

  mov    P1,#%11111111          ;  Now, Wait for the Aileron Capacitor to Charge

Loop3:                          ;  Loop Until the the Line Becomes High
  inc    R4                     ;  Increment the Aileron Position Counter
  jnb    P1.1,Loop3

  mov    A,R3                   ;  Scale the Elevator Value
  clr    C
  subb   A,#4                   ;  Take 4 Away for the Initial Value
  mov    R3,A                   ;  Multiply the Elevator Value Read by 2.5
  rl A                          ;  Rotate Left By one, Multiply by 2  
  xch    A,R3
  clr    C
  rrc A                         ;  Rotate Right by One, Multiply by 0.5
  add    A,R3                   ;  Add 2x and 0.5x Together
  mov    R3,A

  mov    A,R4                   ;  Scale the Aileron Value
  clr    C
  subb   A,#4
  mov    R4,A                   ;  Multiply the Alieron Value Read by 2.5
  rl A                          ;  Rotate Left By one, Multiply by 2  
  xch    A,R4
  clr    C
  rrc A                         ;  Rotate Right by One, Multiply by 0.5
  add    A,R4                   ;  Add 2x and 0.5x Together
  mov    R4,A

  mov    SBUF,#'A'              ;  Indicate We're Sending the Aileron Value
  acall  DlayCheck              ;  Do we Get an Acknowledge?
  jnb    RI,Mainline            ;  If "RI" not Set, then No, Start Over
  clr    RI                     ;  Clear the Received Character Bit

  mov    SBUF,R4                ;  Send the Aileron Value
  acall  DlayCheck              ;  Did we Get an Acknowledge?
  jnb    RI,Mainline
  clr    RI

  mov    SBUF,#'E'              ;  Indicate We're Sending the Elevator Value
  acall  DlayCheck              ;  Do we Get an Acknowledge?
  jnb    RI,Mainline            ;  If "RI" not Set, then No, Start Over
  clr    RI                     ;  Clear the Received Character Bit

  mov    SBUF,R3                ;  Send the Elevator Value
  acall  DlayCheck              ;  Did we Get an Acknowledge?
  jnb    RI,Mainline
  clr    RI

  ajmp   Mainline


DlayCheck:                      ;  Delay 2 Seconds and Check for "RI" to be 
                                ;   Set
  mov    R2,#6
DlayCheckLoop:                  ;  Loop Until Time is Up or "RI" is Set
  jb     RI,DlayCheckEnd        ;   If "RI" Set, Return
  djnz   R0,DlayCheckLoop
  djnz   R1,DlayCheckLoop
  djnz   R2,DlayCheckLoop

DlayCheckEnd:                   ;  Finished, Return to the Caller
  ret