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--- info:howto:water_vapor_pressure_project_notes [2010/09/26 18:35] – created tomgee
+++ info:howto:water_vapor_pressure_project_notes [2010/09/26 18:37] (current) – tomgee
@@ Line 1: / Line 1: @@
+Comments from the W7100 asm program
      ; Calculate vapor pressure from temperature and humidity
      ; DPTR points to start of stream of ASCII Humidity
@@ Line 5: / Line 6: @@
      ; EX: 70F at 65%  = 25.0*.65 = 16.25mbar
      ; WVP (0-13400) returned in A(lsb)B(msb) and output as xxx.x
+Here is the lookup table in the asm program:
+     ; Saturation vapor pressure is a table that starts at -30F and
+     ; continues to 125F in 5 degree steps
+     ; Values in the word table are interpreted with one decimal point (3 = .3)
+     ; Reduced accuracy byte table is interpreted as no decimal points (1 = 1.0)
+     GET_SVP:
+         INC     A
+         MOVC    A,@A+PC
+         RET
+     SAT_VAP_PRES:    ; in millibars
+     ;        DW      3,4,6,7,9,12,15,19,24,30,37,46,56,69,84,102,123,148,177
+     ;        DW      210,250,296,350,410,481,562,656,762,878,1014,1168,1342
+         DB      0,0,1,1,1,1      ; -30 to -5
+         DB      2,2,2,3,4,5      ; 0 to 25
+         DB      6,7,8,10,12      ; 30 to 50
+         DB      15,18,21,25,30   ; 55 to 75
+         DB      35,41,48,56,66   ; 80 to 100
+         DB      76,88,101,117,134 ; 105 to 125